Lasers: Safety, Info, Links, Parts; Diode, HeNe, Ar/Kr Ion Lasers
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Table of Contents
- Introduction - Scope of this document, related information.
- Laser Safety - Hazards to vision, other issues, 100 W light bulb versus 1 mW laser, safety classifications.
- Items of Interest - General Laser Information - Laser power meters, speckle, Fabry-Perot and DFB, more.
- Laser Information Resources - Books, magazines, patents, collections, web resources and links.
- Laser and Parts Sources - Walk-in, mail order, high quality, surplus, laser components and systems manufacturers.
- Diode Lasers - Basic considerations, visible and IR (e.g., from CD player) types, testing, visibility, collimation.
- Diode Laser Power Supplies - Drive requirements, modulation, sample circuits for low and high power devices.
- Helium Neon Lasers - Theory (simple), operation, sealed HeNe tubes, testing, problems, collimation, recharging.
- HeNe Laser Power Supplies - Requirements, types, plug-n-lase, matching tube to PS, problems, testing, repair.
- HeNe Laser Power Supply Design - AC line powered, low voltage inverters, starters, regulators, modulators.
- Complete HeNe Laser Power Supply Schematics - 9 AC line and 4 inverter types, most you can build.
- Argon and Krypton (Rare Gas) Ion Lasers - Basic characteristics, specific examples, setup, maintenance.
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Back to Table of Contents.
Introduction
Scope of this document:
----------------------
Many types of lasers are used in conjunction with popular hobbyist projects,
basement experimentation, and just plain old late night tinkering. Diode and
helium neon (HeNe) lasers in particular are very common due to several factors
including the wide availability of inexpensive components and systems (new and
surplus) and the relative ease of constructing working devices. A greater
number of argon (and krypton) ion lasers will be turning up on the surplus
market at very affordable prices as they are replaced with more modern (but
still very expensive) solid state alternatives.
However, on-line and print resources with detailed information on driving
laser diodes and powering helium neon lasers seem to be scarce. Some of
those that do exist are incorrect and potentially dangerous (or at least
destructive). There appears to be virtually nothing at all on argon/krypton
ion lasers.
This document was written in the hopes of rectifying this situation.
Information is included on lasers in general but with particular attention to
diode, HeNe, and argon/krypton ion lasers.
Our emphasis is on the care and feeding of these types of lasers constructed
from readily available components - not on actually fabricating semiconductor
diode laser chips or HeNe laser tubes (though there are pointers to some of
this information if you are really interested). There is also little in the
way of laser physics and other theoretical topics. (You can now breath a sigh
of relief!) Nor will there be much in the way of the design of laser shows,
holography experiments, interferometers, or other laser applications. I leave
these to the many excellent books and articles that have been published over
the years.
In addition to essential laser safety information, there are *8* circuits for
driving laser diodes, *13* complete schematics for helium neon laser power
supplies, as well as simple modulators and other useful goodies. Most of
these have been tested and/or came from working commercial designs and can be
constructed using readily available inexpensive parts.
The material on argon/krypton ion lasers is still under development but enough
is already included to provide a feel for the capabilities and requirements of
these highly prized devices.
There are also pointers to other web resources, mail order suppliers of laser
parts and equipment, and references on lasers in general.
To the best of my knowledge, no other resource in the explored universe (or
elsewhere) currently comes close to providing as much practical information on
these topics in a form which is both easy to read and readily accessible in
one place - if at all.
Contributions in almost any form are always welcome and will be acknowledged
appropriately.
Please don't discard your unwanted or broken laser related equipment or parts!:
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I am interested in obtaining dead or partially dead lasers and laser parts of
all types and sizes including but not limited to: laser diodes, HeNe and Ar/Kr
or other tubes, laser diode drivers, HeNe and other power supplies or power
supply components, optics, modulators, deflectors, sensors, other types of
circuits, etc.
Obviously I would be interested in working units as well but since this is
strictly for non-profit use to expand knowledge, all I can really pay is
slug mail shipping and maybe a wee bit more for something of sufficient
entertainment value (mine).
Any information found during my dissection or repairs would would eventually
find its way into this continually evolving document.
In addition to hardware, schematics for laser diode drivers, HeNe, Ar/Kr, and
other laser power supplies, as well as other laser related circuits are also of
particular interest. Where permitted, these would be added to this document
or made available at the web sites as well (i.e., they are not proprietary or
in violation of copyright restrictions if made public).
DISCLAIMER:
----------
This document is still under development and will probably continue to be in
this state until will beyond the time when the Sun turns into a red giant or
Hell freezes over, though the Engineers may be able to prevent the latter, at
least :-).
Many of the circuits have been reverse engineered - traced from various
schematics or actual hardware. There may be errors in transcription,
interpretation, analysis, or voltage or current values listed. They are
provided solely as the basis for your own designs and are not guaranteed to be
'plans' that will work for your needs without some tweaking.
We will not be responsible for damage to equipment, your ego, blown parts,
county wide power outages, spontaneously generated mini (or larger) black
holes, planetary disruptions, or personal injury that may result from the use
of this material.
Acknowledgement:
---------------
Thanks to Don Klipstein (email: don@misty.com) for his comments and additions to
this document. His Web site (http://www.misty.com/~don/) is a valuable resource
for information relating to lighting and related technology in general.
Related information:
-------------------
* See the document: "Notes on the Troubleshooting and Repair of Compact Disc
Players and CDROM Drives" for more info on how the laser diodes in CD players
and CD ROM drives worked originally.
Where the manufacturer and part number for your laser diode are known, by all
means take advantage of the extensive applications information that is likely
to be available. Driving laser diodes without blowing them out is often not
easy - even for an experienced design engineer!
* See the document: "Various Schematics and Diagrams" for a variety of circuits
that may be useful in generating the high voltage for belium neon lasers (in
addition to those found in the chapter: "Complete Helium Neon Laser Power
Supply Schematics".
* See the chapter: "Laser Information Resources" for books, magazine articles,
and links to other laser related web sites.
Common lasers of interest to the hobbyist and experimenter:
----------------------------------------------------------
Diode, helium neon (HeNe), and argon/krypton ion (Ar/Kr) lasers are probably
the most popular due to the wide availability of complete lasers and laser
components, and their characteristics including the generation (in most cases)
of a continuous visible beam, manageable power and cooling requirements, and
the fact that there is no need for sophisticated laboratory facilities to keep
them healthy.
While many other types of lasers may be constructed including carbon dioxide
(CO2), mercury vapor ion, nitrogen, dye, ruby, Nd/YAG, free electron, and
X-ray,, these are less common and currently not covered in this document.
There could also be problems obtaining the 100 million volt accelerator
required for the free electron laser and the small nuclear device needed to
pump the X-ray laser :-).
Where any of these are your passion, check out back issues of Scientific
American and/or their reprint collections such as "Light and Its Uses" [5].
There have been many articles and Amateur Scientist columns on lasers and
laser related subjects - particularly during the initial laser craze of the
1960s and 1970s but extending to the present particularly for more exotic
types of lasers and laser applications.
As an aside, I lament the fact that few of the more recent Amateur Scientist
columns have nearly as much sophistication and depth as those from that era.
On the other hand, experiments that are presented may be performed by nearly
anyone who is reasonably handy using parts from the local home center and
Radio Shack and yet this is definitely real science. There is no need for
high vacuum systems, glass blowing skills, strange gas mixtures and other
chemicals, or fancy test equipment!
However, if you are after the highest continuous output power, check out: Understanding
CO2 Lasers - 5,000 W or more OUTPUT for industrial welding,
cutting, machining, and heat treating.
Now, back down to earth :-).
The major characteristics of diode, HeNe, and Ar/Kr ion lasers are summarized
below:
* Diode lasers. Semiconductor laser diode 'chip' driven by low voltage power
supply. Optical feedback from a monitor photodiode (commonly in the same
package as the laser diode) is generally used for precise regulation of
laser diode current.
Wavelengths: Red (635 nm, actually may appear slightly orange-red) through
deep Red (670 nm) and beyond, IR (780 nm, 800 nm, 900 nm, 1,550 nm, etc.) up
to several um). Green and blue laser diodes have been produced in various
research labs but operate at liquid nitrogen temperatures, have very limited
lifespans (~100 hours or worse), or both - you won't find them in any DVD
successor for some time.
Beam quality: Fair (most common) to high depending on design. The raw
beam is elliptical or wedge shaped and astigmatic. Collimation requires
external optics. Coherence length usually only a few mm.
Power: .1 mW to 5 mW (most common), up to 100 W or more available.
Some applications: CD players and CDROM drives, LaserDisc, MiniDisc, other
optical storage drives; laser printers and laser fax machines; laser
pointers; sighting and alignment; measurement; high speed fiber optic and
free space communication; pump source for other lasers; bar code and UPC
scanners; high performance imagers and typesetters, small light shows.
Cost: $15 to $10,000 or more.
Comments: Inexpensive, low (input) power, very compact. However: drive
is critical. Diode lasers are not generally suitable for holography or
interferometry where a high degree of coherence and stability are required.
* Helium neon (HeNe) lasers. Sealed HeNe plasma tube with internal mirrors,
high voltage power supply.
Wavelengths: red (632.8 nm) is most common by far. Orange (611.9), yellow
(594.1 nm), green (543.5 nm), and IR (1,523.1 nm) HeNe lasers are also
readily available (but these are less efficient and therefore more costly
for the same beam power).
Beam quality: Extremely high. The output is well collimated without
external optics, and has excellent coherence length (10 cm to several meters
or more) and monochromicity. Most small tubes operate single mode (TEM00).
Power: .5 to 10 mW (most common), up to 250 mW or more available.
Some Applications: Industrial alignment and measurement; blood cell counting
and analysis); medical positioning and surgical sighting (for higher power
lasers); high resolution printing, scanning, and digitization; bar code and
UPC scanners, interferometric metrology and velocimetry; non-contact
measuring and monitoring; general optics and holography; small to medium
size light shows, laser pointers, LaserDisc and optical data storage.
Cost: $25 to $5,000 or more depending on size, quality, new or surplus.
Comments: Inexpensive, components widely available, robust, long life.
* Argon (Ar) and krypton (Kr) ion lasers. These differ mainly in gas fill.
Sealed plasma tube with internal or external mirrors and high current (10
amps or more at around 100 VDC) regulated power supply (constant current
or optical power based). Combined Ar/Kr produces lines in red, green, and
blue, and is therefore considered a 'white light laser'. All are electrical
power guzzlers and larger units are water cooled.
Wavelengths: Violet blue (457.9 nm), blue (488 nm - single line), green
(514 nm), Red (Kr or Ar/Kr types only, 646 nm). Many other lines throughout
the visible spectrum (and beyond) are available (but generally weaker) and
may be 'dialed up' on some models.
Power: 10 mW to 10 W. Research lasers up to 100 W.
Beam quality: High to very high. Single and multimode types available.
Some applications: very high performance printing, copying, typesetting,
photoplotting, and image generation; forensic medicine, general and
ophthalmic surgery; entertainment; holography; electrooptics research;
and as an optical 'pumping' source for other lasers.
Cost: $500 (surplus 100 mW) to $50,000 (multi-watt new) or more.
Comments: High performance for someone who is truly serious about either
optics experiments like holography or medium to high power light shows.
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Laser Safety
You only received one set of eyeballs?:
--------------------------------------
Lasers have tended to be high glamor devices popular with with hobbyists,
experimenters, entertainers, and serious researchers alike. However, except
for very low power lasers - those with less than a fraction of a mW of beam
power - they do pose some unique hazards particularly with respect to instant
and permanent damage to vision.
There are several reasons for this even for lasers which do not represent any
sort of burning or fire risk:
* The output of many lasers is a nearly parallel - highly collimated - beam
which means that not only is the energy concentrated in a small area but the
lens of the eye will focus it to a microscopic point on the retina instantly
vaporizing tissue in much less than the blink of an eye. A collimated beam
represents the rays from an object at infinity so if your eye is focused for
distance, the laser will be in focus as well. Even a common helium neon
laser without external optics will approximate a point source a .5 meter or
more behind the exit window of the laser. Where your are working in a small
room, this approximate distance would likely be where your eyes are focused.
While purists might argue that the lens of the eye isn't perfect and will
not produce a diffraction limited spot on the retina, this won't save your
vision! The power density in a sub-optimal spot can still be astronomical.
A cheap laser pointer also produces a highly collimated beam.
Even at power levels considered relatively safe, one shouldn't deliberately
stare into the beam for any reason. For these relatively low power lasers,
permanent eye damage is not that likely but why take chances? For these
lasers, viewing the spot projected on a white surface is perfectly safe.
* An output of 1 mW may not sound like much compared to a 100 W light bulb
but consider:
A 100 W light bulb puts out about 5 to 7 W of visible light (the rest is
mostly IR and heat) more or less uniformly distributed in all directions.
However, at any reasonable distance from the light bulb, the power density
(e.g., W/sq. mm) is much lower than for a collimated laser beam of even very
low power. And, it takes significant effort to produce any sort of truly
collimated beam from such a non-point source such as is present with even
the filament of a clear light bulb. However, for a helium neon laser, the
collimation is such that the entire beam (total power output of the laser)
will still be small enough to enter the eye even at a distance of several
meters.
For example, at 10 cm from a 100 W bulb (which would be a very uncomfortable
place to be just due to the heat), the power density assuming 6 total watts
of light would be only about .05 mW/sq. mm. At 1 m, it would be only .0005
mW/sq. mm or 500 mW/sq. m. Based on this back-of-the-envelope calculation,
a 5 mW laser beam spread out to a circular spot of .1 m diameter (i.e., 1 mR
divergence at a distance of 50 m - without external optics) will be brighter
than the 100 W light bulb at 1 m! And, close to the laser itself, that beam
may be only 1 *mm* in diameter and thus 10,000 times more intense!
* As another point of reference, the mid-day Sun at the Earth's equator on a
clear day has a power density of about 1 KW/square meter or about 1 mW/sq.
mm. It would not take very long staring into the Sun to burn out your
eyeballs!
See the section: "Other web resources" for links to laser safety web sites.
A popular graveyard joke in the laser industry is: "Do not stare into the
beam with your remaining good eye". Nonetheless, laser safety is no laughing
matter.
Why a 1 mW helium neon laser still appears bright a mile away:
-------------------------------------------------------------
At a distance of 1 mile (1,609 m), the beam from a typical helium neon laser
(which is a quite well collimated source) will have spread to a diameter of
roughly 4 feet (48 inches, 1.3 m). However, it will still appear quite
bright. Why is this so?
(Portions of the following from: Don Klipstein (don@Misty.com)).
The fraction of light entering the eye for a large diameter beam is pupil area
divided by beam area.
Assuming a pupil diameter of 1/4 inch (6.3 mm, rather dilated but not fully
dark adapted which may approach 1 cm). The portion of the beam entering the
eye would then be the square of (1/4)/(48), which is about 27 millionths of
the total. Since the 4 foot diameter beam is not uniform but dimmer towards
the edges, I would say the eye could get about 35 millionths of the beam near
the center or 35 nanowatts (35 nW).
Note that close to the laser, the pupil size is going to be larger than the
beam diameter (which is typically less than 1 mm) and pupil size larger than
this will not affect the maximum possible power entering the eye (though it
will affect the probability of this occurring. (One suggested laser safety
practice is to brightly illuminate the laser lab to make your pupils smaller.
Even though there are times this will not reduce the severity of the worst
case, a smaller target reduces likelihood of this happening.)
However, where the beam diameter is equal to or larger than the pupil
diameter, the difference in pupil diameter between bright and dark adapted
eyes will be very significant - more than a 30-fold difference in power
entering the eye for this analysis.
I calculate that a 4 foot diameter 1 mW 632.8 nM beam appears about as bright
as a 100 W bulb does 88 feet away.
Although 35 nW is definitely eye-safe, it may look quite bright against pitch
black surroundings especially when the eye is fully dark adapted (the pupil is
wide open and the combined retinal/neural sensitivity is maximum as it is
after awhile when out at night) and may quickly result in a noticeable
afterimage. The effect is probably enhanced by the knowledge that the light
source is a laser and thus potentially damaging to your eyesight.
As a side note, the 1,710 lumen output of a typical 100 watt incandescent bulb
is about the same lumens as *10 Watts* of 632.8 nm light!
Safety issues with respect to small lasers:
------------------------------------------
The most common types of lasers generally available to hobbyists - CD laser
diodes, visible laser diodes, laser pointers, and small HeNe lasers, are all
rated Class II or IIIa. See the section: "Laser safety classification".
Class II lasers should be relatively low risk if even minimal precautions are
taken. However, Class IIIa lasers must be taken much more seriously if the
beam is well collimated - as it would be from a laser pointer or HeNe laser
tube.
In addition, with helium neon lasers, high voltage power supplies are involved
so there is the added shock hazard resulting from touching or accidentally
coming in contact with uninsulated connections. See the document: "Safety
Guidelines for High Voltage and/or Line Powered Equipment" before working on
any type of equipment which uses line voltage or produces high voltage. Most
of these are quite low power so the actual risk of electrocution from the high
voltage side is relatively small but there may be AC line voltage involved and
there can be collateral damage from a reflex response to the shock. In
addition, a homemade power supply, in particular, may use components which are
grossly oversized for the application (due to low cost availability) like a
15,000 V, 400 W neon sign transformer even though only under 10 W of power is
actually needed (we definitely do NOT recommend this approach).
Furthermore, you may come across a truly high power CO2 or argon ion laser, or
even a 50 mW helium neon tube. These, rated Class IIIb or Class IV, represent
much more significant risks of both instant permanent eye damage even from
momentary reflections from shiny (specular) surfaces as well a very real fire
hazard. In addition there is a very real danger of electrocution from the
high voltage high current power supplies used to power these beasts. Since
this document does not deal in detail with these types of lasers, the
essential additional precautions that must be taken are not covered. However,
you must handle them properly for your own safety and the safety of others
around you and your surroundings.
The following very large number is designed to impress: The power density
of a 1 mW laser beam when focused to a spot of around 2 um (which isn't
difficult with a simple convex lens) is around 250,000,000 W per square meter!
Be Extremely Careful When Working with any laser!
(From: Tjpoulton (tjpoulton@aol.com)).
A 1 mW diode will probably not cause damage if you briefly look into it, but I
wouldn't encourage you to try it. While it probably won't do anything bad, it
is not good to become comfortable with the idea of checking the operation of
lasers by looking into them. If you are a hobbyist who uses lasers quite a
bit, there is a good chance you will, at some point, end up with an unmarked
diode. It could emit any wavelength at any power level, and how bright the
beam appears when you shine it on something has no bearing on the power level.
Looking into an unmarked diode just because the beam is dim could (and
probably will) have disastrous results. I have a 1 W 808 nm laser diode, and
it appears much dimmer than a .5 mW 670nm beam when focused into a .2 mm spot.
When focused in that way, it will easily engrave plastic and burn paper and
wood (and skin). Just because it looks dim doesn't mean it won't instantly
blind you.
(From: Daniel P. B. Smith (dpbsmith@world.std.com)).
Be aware that eye damage that is localized to a small area of the eye is not
very noticeable. For example, few people ever notice the existence of the
large blind spot where the optic nerve enters the eye even though it is rather
huge (10 degrees or so) and not all that far from central vision. A laser
wouldn't necessarily have to make you totally blind; it could just wipe out a
teeny patch here and a teeny patch there. This kind of damage would be very
insidious; each time you'd say "Wow! That was bright! lucky I didn't get
blinded" - while slowly and cumulatively losing your sight...
Caution about depending on neutral density filters for protection:
-----------------------------------------------------------------
(From: Don Klipstein (don@Misty.com)).
While thumbing through some gel filter sample packs, it has occurred to me that
there are neutral density gel filters - and that they are not truly neutral.
Both Gam and Rosco ones are somewhat neutral through to about 700 nM - and
become more transparent as wavelength increases through the low and mid 700's.
They are nearly transparant above about 750 nM.
They also have a slight peak at 380 nM, where they are a bit more transparent
than they are to visible light. Transmission at 380 can exceed the average
visible transmission for darker grays.
This is because these filters are made gray with some kludge of dyes rather
than something truly neutral-density. They also do not equally attenuate all
visible wavelengths; they have transmission peaks around 480 (greenish blue)
and 600 (orange), and absorption peaks around 450 (mid-blue) and the mid 500's
(yellowish green). Different brands may have some differences, as well as
having some similarities. They probably have some but not all dyes in common.
I do not know whether the infrared transparency is an unavoidable consequence
of dying plastics/gels, or something intentional to reduce filter heating. I
do know that the colored filter gels are also nearly transparent to most
wavelengths from the upper 700's (sometimes low 700's) through probably at
least around 1500 nM.
Because of this, dark filter gel combinations are probably unsafe for directly
viewing the sun, and are probably unsafe for attempting to protect eyes from
infrared lasers.
Laser safety classification:
---------------------------
(From: Don Stauffer (stauffer@htc.honeywell.com)).
There are ANSI standards, OSHA standards, and military standards. The best
discussion of these, plus general treatment of the topic, is a book by Sliney
and Wolbarsht, "Safety with Lasers and Other Optical Sources," Plenum Press,
New York.
The following is based on material from the Laser Safety Manual of the
University of Waterloo:
All lasers are classified by the manufacturer and labelled with the
appropriate warning labels. Any modification of an existing laser or an
unclassified laser must be classified by the Laser Safety Officer prior to
use. The following criteria are used to classify lasers:
1. Wavelength. If the laser is designed to emit multiple wavelengths the
classification is based on the most hazardous wavelength.
2. For continuous wave (CW) or repetitively pulsed lasers the average power
output (Watts) and limiting exposure time inherent in the design are
considered.
3. For pulsed lasers the total energy per pulse (Joule), pulse duration, pulse
repetition frequency and emergent beam radiant exposure are considered.
Lasers are generally classified and controlled according to the following
criteria:
* Class I lasers - Lasers that are not hazardous for continuous viewing or are
designed in such a way that prevent human access to laser radiation. These
consist of low power lasers or higher power embedded lasers. (i.e. laser
printers)
* Class II visible lasers (400 to 700 nm) - Lasers emitting visible light which
because of normal human aversion responses, do not normally present a
hazard, but would if viewed directly for extended periods of time. (like
many conventional light sources).
* Class IIa visible lasers (400 to 700 nm) - Lasers emitting visible light not
intended for viewing, and under normal operating conditions would not
produce a injury to the eye if viewed directly for less than 1000 seconds.
(i.e. bar code scanners).
* Class IIIa lasers - Lasers that normally would not cause injury to the eye if
viewed momentarily but would present a hazard if viewed using collecting
optics (fibre optics loupe or telescope).
* Class IIIb lasers - Lasers that present an eye and skin hazard if viewed
directly. This includes both intrabeam viewing and specular reflections.
Class IIIb lasers do not produce a hazardous diffuse reflection except when
viewed at close proximity.
* Class IV lasers - Lasers that present an eye hazard from direct, specular
and diffuse reflections. In addition such lasers may be fire hazards and
produce skin burns.
The following relates the laser classifications to common laser types and
power levels:
(From: Richard Trotman (trotman@udel.edu)).
I'm paraphrasing from "Introduction to Lasers", C.O.R.D., 1990:
* Class I - EXEMPT LASERS, considered 'safe' for intrabeam viewing. Visible
beam.
Maximum power less than 0.4 uW.
* Class II - LOW-POWERED VISIBLE (CW) OR HIGH PRF LASERS, won't damage your
eye if viewed momentarily. Visible beam.
Maximum power less than 1 mW for HeNe.
* Class IIIa - MEDIUM POWER LASERS, focused beam can injure the eye.
HeNe power 1.0 to 5.0 mW.
* Class IIIb - MEDIUM POWER LASERS, diffuse reflection is not hazardous,
doesn't present a fire hazard.
Visible Argon laser power 5.0 to 500 mW.
* Class IV - HIGH POWER LASERS, diffuse reflection is hazardous and/or a fire
hazard.
The classifications depend on the wavelength of the light as well.
Hobbyist projects and laser safety classifications:
--------------------------------------------------
While many of the partial circuits and complete schematics in this document
can and have been used in commercial laser products, important safety
equipment has generally been omitted to simplify their presentation. These
range from simple warning labels for low power lasers (Class I, II, IIIa) to
keyswitch and case interlocks, beam-on indicators, and other electrical and
mechanical safety devices for higher power lasers. Laser safety is taken
very seriously by the regulatory agencies. Each classification has its own
set of requirements.
The following brief summary is just meant to be a guide for personal projects
and experimentation (non-commercial use) - the specifics for each laser class
may be even more stringent:
* For diode lasers and HeNe lasers outputting 5 mW or less (Classes 1, II,
IIIa), packaging to minimize the chances of accidental exposure to the beam
and standard laser warning labels should be provided.
* Where the case can be opened without the use of tools, interlocks which
disable the beam are essential to prevent accidental exposure to laser
radiation (Class IIIa and above). Their activation should also remove
power and bleed off any dangerous voltages (ALL HeNe and argon/krypton
lasers).
* A beam-on indication is highly desirable especially for lasers emitting
invisible IR (or UV).
For more information on specific requirements, see the chapters on 'Control
Measures' in the laser safety manuals at the Laser Safety Links web site.
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Back to Table of Contents.
Items of Interest - General Laser Information
What makes a laser power meter so expensive?:
--------------------------------------------
Commercial laser power meters cost $300 and up - $1,000 is a more typical
price for something that works over a wide range of power levels and
wavelengths. Where the precision and automatic wavelength calibration of
these instruments is not needed, a basic laser power meter can be built
inexpensively. See the section: "Sam's super cheap and dirty laser power
meter".
There are several ways to design a device that will determine the power in a
beam of light. Here are two:
* Photodiode - each photon within the wavelength range of the device creates
an electron-hole pair. When reverse biased, this results in a current flow
which is proportional to light flux.
* Thermo-electric - the beam hits a sensor that absorbs (nearly) 100 pecent
of the incident light energy at the range of wavelengths in question - a
black body. This raises its temperature with respect to a known reference
with a known thermal resistance between them.
Here are some comments on these approachs:
(From: Bill Sloman (sloman@sci.kun.nl)).
The important thing to note is that a photo-diode actually detects photons,
not power. Up to about 850nm, each photon actually reaching the diode junction
generates one pair of charge carriers. A 425nm photon, carrying twice the
energy of an 850nm photon generates the same pair of charge carriers, so the
same current represents the absorption of twice the power.
Since the 425 nm photon has rather less chance than the 850 nm photon of
actually surviving the trip down to the diode junction, so the actual ratio is
closer to 2.5:1.
Above 850 nm, the photons haven't got quite enough energy to separate a pair
of charge carriers, and can only separate those that are already somewhat
excited. The proportion that are sufficiently excited depends on temperature.
A electric field also helps, so biasing the diode increases it sensitivity to
long wavelength photons. As the wavelength rises above 850nm the extra energy
required to separate the charge carriers also rises, so the proportion of
'sufficiently excited' carriers declines quite rapidly.
In principle one could build a wavelength correction into the power meter,
but you would need to add a wavelength sensor to the power meter to make it a
useful feature.
The Centronics data book gives a typical spectral response for the 5T series
diodes, which effectively gives you the inverse of the wavelength correction
function, albeit with rather low precision.
The alternative approach is to use a sensor which responds to the heating
effect of the laser beam. These exist, but what you win on wavelength
independent calibration, you lose on sensitivity and zero stability - in
effect you have built a thermometer to measure the heating effect of your
laser beam on a more or less thermally insulated target. Unless someone has
done something very neat in this line, it doesn't strike me as a practical
proposition for your application, granting your limited budget.
Sam's super cheap and dirty laser power meter:
---------------------------------------------
Hobbyists and experimenters may not need the super precision or automatic
features of a commercial (and costly) laser power meter. For example, the
wavelength or wavelength distribution of the laser source is almost always
known. Therefore, if a correction needs to be computed using mushware (i.e.,
the stuff between your ears), so be it. There will be no absolute reference
either but calibration using a source with known output power and wavelength
like a 1 mW HeNe 632.8 nm laser will work just fine. And, if you really want
a 16 digit LCD display, one can always be added :-).
I tossed this together using a 4 segment photodiode chip from a dead and
abandoned Mouse Systems optical mouse (the old type which uses a pair of
these chips - one for each axis). The active area of each segment is about
1 mm x 1.4 mm (total about 1 mm x 5.6 mm) which isn't great but is adequate
to capture the entire beam of a typical collimated laser diode or HeNe laser.
A larger area photodiode would be better. To ease this a bit, I tied all 4
segments in parallel so one dimension is no problem at all. There are
microscopic gaps between the segments but I estimate it to be less than 5
percent of the area so the loss should not be a big problem.
An 'instrument' (this term is being used very generously!) of this type will
not replace a $1,000 commercial laser power meter but may be sufficient for
many applications where relative power measurements are acceptable and/or
where the user is willing to do a little more of the computation :-). One
cannot complain about the cost: $0.00.
The basic circuit is as follows:
R1 1K 1 2
Vcc o---------/\/\---------+----|<|----+
| 4 3 |
+----|<|----+ U1
| 5 6 | AE1004
+----|<|----+
| 8 7 |
+----|<|----+
M1 |
+---------+ |
- | 0-10 mA | + | PD
Gnd o------| \ |-----------------+
| o | <- I
+---------+
* The meter (M1) I used was a D'Arsenval moving coil type that had a full scale
sensitivity of 10 mA. A suitable shunt can be used with a more sensitive
meter or just use one of the current ranges of your VOM or DMM.
R1 provides current limiting to protect the meter movement from vaporization
should the photodiode array short out. The combination of Vcc and R1 just
needs to meet the requirement that the photodiode array remains reverse
biased at the maximum expected current (optical power).
For the value of R1 shown above, Vcc should be at least 4 VDC for a
photodiode current up to about 3 mA.
* I do not know the maximum ratings of this photodiode array but it seems to be
fine with Vcc up to at least 12 VDC. Since current is nearly independent of
the bias voltage, Vcc is not at all critical.
* Sensitivity is about .45 mA/mW at 632.8 nm from a HeNe laser. Though I have
nothing precise to calibrate it against, the readings were consistent and
linear with the tubes I tried which had their output power labeled.
* Mount the photodetector on a 'third hand' type of mount so it can be easily
positioned in the beam path.
* A lens can be used to reduce the beam diameter of your laser so that the
entire beam fits within the area of the photodetector. Where the beam
profile exceeds the dimensions of the photodetector, an estimate of beam
power can still be made knowing the ratio of sensor area to total beam area.
Unfortunately, with the small area of the photodetector, using this with
intact CD laser optics may not be that easy.
* The range of wavelengths over which this is useful should extend throughout
the visible spectrum into the near IR - at least until 850 nm or so.
I do not know what precise effect different wavelength lasers will have on
the sensitivity of this circuit. Shorter wavelengths are more energetic but
generate the same number of charge carriers (i.e., same current) and have
less chance of surviving the trip through the diode junction. Thus, for a
given photon flux the power reading will be low at shorter wavelengths. A
correction factor can probably be computed.
* I also do not have any idea at what point the photodiode array will be
damaged due to thermal effects. This is certainly not a problem for up to
10 mW as long as it is not focused to a sharp point.
A pair of op-amps can be added to provide more flexibility. The following
circuit is substituted for the meter (M1), above. Any general purpose op-amps
(e.g., 741) powered from +/- 12 VDC (for 10 V full scale) can be used.
R2 1.11K
+------/\/\------o X1
| R3 11.1K X10 S1 Range Select
+------/\/\----o <---o--+
| R4 100K |
+------/\/\---+--o X100 | R6 1K R7 5K Calibrate
| | | +---/\/\---/\/\---+
I-> | |\ | | | | |
PD o-----+---|- \ | | R5 1K | |\ +----+
| >----+---------+---/\/\---+---|- \ |
+---|+ / | >--------+----o +
_|_ |/ U2 +---|+ / Vout
- _|_ |/ U3 +--o -
- _|_
-
This circuit provides 3 ranges. R7 (calibrate) allows the sensitivity to be
adjusted for your particular photodiode and laser wavelength. With R7 set to
1.22 K, the ranges will be .01 mW, .1 mW, and 1 mW per V of Vout at 632.8 nm.
Vout can also be monitored with a scope or connected to an audio amplifier
to detect an amplitude modulated laser beam.
For the Range Select switch (S1), make-before-break contacts are recommended
to prevent high amplitude glitches when changing ranges.
For my photodiode array, the dark current was insignificant. Should this not
be the case with your device a potentiometer tied to a negative reference can
be used to null it out by injecting an equal and opposite current at the (-)
input to U2.
Many variations and enhancements to this circuit are possible.
So how many photons are coming out of my laser?:
-----------------------------------------------
This is a simple calculation based on knowing the energy of each photon (based
on wavelength):
1,240 nm
E = 1.602E-19 J * -------------
lambda
Where: lambda is the wavelength of your light source.
1,240 nm is the photon wavelength with an energy of 1 ev.
Then, photon flux = P/E where P is the beam power.
For example, a 1 mW, 620 nm source will produce about:
1E-3 / (1.602E-19 * 2) = 3E15 photons/second.
About laser speckle and other phenomena:
---------------------------------------
Speckle is a mottled pattern that arises when laser light falls on a
non-specular reflecting surface. Lasers with high spatial and temporal
coherence properties are likely to produce dramatic speckle effects. Thus,
gas lasers like HeNe types are more likely to exhibit this effect than laser
diodes.
For those applications where the laser's bright light and its ability to be
sharply focused or easily collimated are important but coherence is irrelevant,
speckle is an undesirable side effect to be avoided.
(From: Mike Poulton (tjpoulton@aol.com)).
If you want any more information on any kind of laser, or sources for parts to
build them, post your question on alt.lasers. There, a group of about ten
laser enthusiasts (including myself) will jump on your question and answer it
in every possible way and in great detail.
As for the speckle pattern, that is usually called the interference pattern.
It has nothing to do with your eyes and has no bearing on how well you can see
as it is a real phenomenon. Laser light is completely monochromatic and is
also in phase. When this light is scattered, it gets out of phase and the
waves collide. When a wave at a low point and a wave at a high point collide,
they cancel each other out (just like those noise-reduction machines that send
out ambient sound 180 degrees out of phase, except this is with light). Where
the light cancels itself out, there is a dark space, where it does not, there
is a light space. This creates a three-dimensional lattice-work of light and
dark spaces.
As you move around it, you see different parts of the lattice and your view
appears to move. The more "saturated" the area is with light, the more
impressive this effect is. I have a 15mW Helium-Neon laser, and its effect is
incredible. To say that this is in your head is like saying that it is an
optical illusion when you look at different sides of a house. One cool thing
to try is shining the laser into flood light (while it is turned off). The
reflective coating on the inside of the bulb makes this effect very intense.
(From: J. B. Mitchell (ugez574@alpha.qmw.ac.uk)).
Speckle noise arises because of the highly coherent nature of the laser light
and can thus be reduced or eliminated by reducing the coherence of the source.
One easy way of achieving this is by introducing a rotating ground-glass screen
into the beam. Placing the ground glass at the focus of the beam reduces the
temporal coherence by introducing random phase variations while maintaining the
spatial coherence (ability for the beam to be focused to a point). Putting
the ground glass in an unfocussed beam reduces both the temporal and spatial
coherence.
Alternatively, if you need to maintain the coherence for your application
(interferometry, for example) the you can reduce the size of the speckles
by increasing the aperture of the imaging system.
(From: Steve McGrew (stevem@comtch.iea.com)).
I know of three ways:
1. Increase the spatial frequency of the speckle so that it is so high it
ceases to be a problem.
2. Use only specular objects and sources.
3. Decrease the temporal and/or spatial coherence of your laser beam by
running it through something like a rotating diffuser.
(From: Guy Mark Tibbert (gmt@weirdness.com)).
You can always use a pair of lenses, one to focus the beam down, then pass it
through a pinhole and then another lens to bring it back to a co-linear
beam. The pinhole method is crude but DOES reduce speckle quite well enough
for most applications. You will need to experiment with the pinhole diameter
for the best results. Obviously the material you make the pinhole from will
need to depend on the power of the laser and the durability of the finished
article.
Difference between Fabry-Perot and DFB lasers:
---------------------------------------------
The Fabry Perot laser design is what most people think of: lasing medium
with mirrors at each end.
(From: Dr. Mark W. Lund (lundm@acousb)).
A Fabry-Perot cavity is the standard run of the mill cavity with two highly
reflecting mirrors bouncing the light back and forth, forming a standing wave.
This cavity is not very frequency selective, theoretically you could have 1 mm
wavelength light and .001 micron wavelength light in the same cavity, as long
as the mirrors are the right distance apart to form a standing wave (and higher
order modes make this easier than you might think).
A distributed feedback laser replaces the back mirror with a grating along the
cavity axis. Instead of being reflected abruptly like a metal mirror would,
the grating reflects a little over each part of the grating until at the back
of the grating the light has petered out. Of course, since the light is being
reflected by the grating the reflected light is always in the correct phase
no matter if it was reflected from the front or back of the grating. The
distributed nature of the reflection sharpens the cavity resonance and
distributed feedback lasers are typically of much narrower bandwidth than the
same laser with mirrors. Mostly seen in laser diodes, distributed feedback
can also be done with non-linear optics, volume gratings, and other more
esoteric optical elements.
(From: Bret Cannon (bd_cannon@pnl.gov)).
Fabry-Perot lasers are made with a gain region and a pair of mirrors on the
facets, but the only wavelength selectivity is from the wavelength dependence
of the gain and the requirement for an integral number of wavelengths in a
cavity round trip.
DFB (Distributed Feed Back) lasers have the a periodic, spatially-modulated
gain, which gives a strong selectivity for the wavelength that matches the
period of the gain modulation. DFB lasers lase in the same single longitudinal
mode from threshold up to the maximum operating power while Fabry-Perot lasers
hop from one longitudinal mode to another as the current and/or temperature
change. Most Fabry-Perot lasers lase on several longitudinal modes
simultaneously though with some of these lasers you can find currents and
temperatures where they lase on only a single mode.
The are also DBR (Distributed Bragg Reflector) lasers that have a Bragg
reflector, that is a volume grating, as the reflector at one end of the
cavity, which provides wavelength selective feedback. These lasers lase
on a single longitudinal mode but the lasing hops from longitudinal mode
to longitudinal mode to stay near the peak of the reflectivity of the
Bragg reflector as temperature and current are changed.
Comments on various color lasers:
--------------------------------
(From: Mike Poulton (tjpoulton@aol.com)).
Laser diodes have only been able to produce red and infrared beams so far
(at least commercially). There have been some research reports of green
and possibly blue laser diodes but only operating in pulse mode, at reduced
temperature, and/or with very limited lifetime. This will no doubt change
as enormous incentives exist to develop shorter wavelength laser diodes
numerous applications.
The green lasers you see are either argon or frequency-doubled Nd:YAG
(neodymium doped yittrium-aluminum-garnet). The argon laser is a very
large and complex device, almost always putting out hundreds of times the
power of your pointer. A Nd:YAG laser is usually even more powerful, but
is often pulsed. Diode lasers are not used in laser light shows because
they are never powerful enough. I am sitting here typing this while
allowing my 15mW Helium-Neon laser to stabilize and warm up. Its
wavelength is shorter, and it is 3 times more powerful than the pointer.
When a red beam is needed in a laser light show, these are usually used
because they are usually more powerful than diodes, and the beam is more
visible per milliwatt because of it's shorter wavelength. Happy Lasing,
and be sure to visit alt.lasers for any laser info you need!
Relative visibility of light at various wavelengths:
---------------------------------------------------
The following table lists the relative sensitivity of the Mark-I eyeball to
wavelengths (including common laser sources) of light throughout the visible
spectrum and somewhat beyond. Of course, not eveyone comes equally equipped.
Your mileage may vary (and the number of significant figures in some of these
entries should not be taken too seriously)!
(Portions of the following from: Don Klipstein (don@Misty.com)).
Wavelength Response Color Typical source/application
----------------------------------------------------------------------------
350 nm .00001? UV
380 nm .0002 Near UV
400 nm .0028 Border UV
420 nm .0175 Violet
442 nm .0398 Violet-blue Violet blue line of HeCd laser
450 nm .0468 Blue
457.9 nm .0562 " Blue line of argon ion laser
488 .191 Green-blue Green-blue line of argon ion laser
500 nm .323 Blue-green
514 nm .588 Green Green line of argon ion laser
532 nm .885 " Green freq.-doubled Nd (including YAG)
543.5 nm .974 " Green HeNe laser
550 nm .995 Yellow-green
555 nm 1.000 " *** Reference (peak) wavelength ***
568 nm .964 " Y-G line of some krypton ion lasers
580 nm .870 Yellow
594.1 nm .706 Orange-yellow Yellow HeNe laser
600 nm .631 Orange
611.9 nm .479 Red-orange Orange HeNe laser
632.8 nm .237 Orange-red Red HeNe laser
635 nm .217 " Laser diode (DVD, newer laser pointers)
647.1 nm .125 Red Red line of krypton or Ar/Kr ion laser
650 nm .107 " Laser diode
660 nm .061 " Laser diode
670 nm .032 " Laser diode (UPC scanners, old pointers)
680 nm .017 "
685 nm .0119 Deep red
690 nm .0082 "
694.3 nm .006 " Ruby laser
700 nm .0041 Border IR
750 nm .00012 Near IR
780 nm .000015 " CD player/CDROM/LaserDisc laser diode
800 nm 3.7E-6 "
850 nm 1.1E-7 "
900 nm 3.2E-9 "
1,064 nm 3E-14 " Nd lasers (including YAG)
1,523.1 nm 0.0000 " IR HeNe laser
10,600 nm 0.0000 IR CO2 laser
This is according to the 1988 C.I.E. Photopic Luminous Efficiency Function.
The C.I.E. ("Committee Internationale d'Eclairage") may also be known by
other initials indicating the English translation (ICI for "International
Commission on Illumination").
A variety of information on color perception including many charts, tables,
references, and links, can be found at the Color and Vision Research
Laboratories of the University of California, San Diego. However, the
corresponding table at this site is the older 1931 version. In 1988 C.I.E.
updated the Photopic Luminous Efficiency Function because the 1931 function
did not sufficiently weight the higher blue response of young people.
* Values from 380 to 780 nm in multiples of 1 nm are from this table, then
rounded to 3 significant figures.
* Values in between are linearly interpolated, then rounded to 3
significant figures. In close calls, rounding was done in the direction
indicated by whether this function is concave up or down.
* Values outside this range are extrapolated exponentially. For longer
wavelengths, it is assumed that visibility will be cut in half for every 10
nm increase in wavelength.
For all intents and purposes, wavelengths beyond 1,000 nm are absolutely and
totally invisible - period! (In other words, the only way you will seen them
is for about a microsecond before your eyeballs, your head, or you in the
entirety is vaporized due to the high power required --- sam).
I know that argon lasers have a blue line (457 nm), a green-blue one (488 nm),
an emerald-green one (514), and a yellow-green one. I don't know the other
wavelengths. I have seen them in the less extreme two (deep blue-green
color), and the more extreme two (slightly whitish blue-green color). Every
time I ever got a spectrum of these, I saw the 488/514 lines or the roughly
457 and 560 lines. Never 1 or 3 or 4 nor other combinations of 2 in my very
small sample. The strongest lines for argon are at 488 and 514 nm. The one
at 488 nm is found in single line argon ion lasers.
Note that wavelengths from around 460 through the low 500's can be more
visible in dim environments than indicated by the C.I.E. 'Y' function due to
scotopic vision. Scotopic vision peaks in the 500 to 515 nm range, and the
ratio of scotopic to photopic is maximized in these and somewhat lower
wavelengths down through around 460.
In addition scotopic vision can be very significant even at brightnesses high
enough to permit some color vision. Some preliminary data that I have
indicates some significance of scotopic vision at up to 100 to 200 lux for
viewing more than about 3 degrees off the axis of the eye. This is lower
ranges of ordinary room lighting.
Also see the sections: "Visibility of Near-IR (NIR) laser diodes" and "Spectra
of visible and IR laser diodes".
Comments on spatial and temporal coherence:
------------------------------------------
(From: Daniel Marks (dmarks@uiuc.edu)).
There are really two coherences associated with any source; spatial and
temporal coherence. Probably the coherence you are referring to is temporal
coherence, but both are important for holography.
The temporal coherence is related to the bandwidth of the source. The more
narrow the bandwidth of the source, the longer the coherence length. HeNe
lasers have a very narrow bandwidth, as a result they have a coherence length
on the order of 10-30 cm. LED's are incoherent sources, they only have a
coherence length of 10-40 microns, and a large bandwidth of several kT (25.9
meV at 298K) or I'm guessing 10 nm of bandwidth (around about 650 nm). HeNe
lasers are also much more spatially coherent than LEDs. The spatial coherence
length is determined by the cavity and cavity reflectivity in a laser. LEDs
also have a very short spatial coherence length, or only a couple of
wavelengths.
The coherence length is the maximum distance at which two points in the field
can be interfered with contrast. The temporal coherence length determines the
maximum depth of the object in a reflection hologram, and the spatial coherence
length determines the lateral size. Using techniques of "white light"
interferometry, incoherence sources can be used, but they are tricky and have
many restrictions on the kinds of holograms one can create.
Also see the section: "Coherence length of HeNe lasers".
Laser beam collimation:
----------------------
(From: Kai-Martin Knaak (kmk@physik.uni-mainz.de)).
There is a maximum distance that a beam of light can be kept collimated.
Usually it is called 'Rayleigh length' and it depends on the wavelength and
the minimum diameter of the beam. If the beam diameter is w0 at point z, then
the beam will have expanded to at least 1.4 times w0 at Rayleigh-length
distance from z.
The Rayleigh length, z_rayleigh, can be calculated like this:
z_rayleigh = pi * (minimum diameter)/(wavelength)
For example, assuming a HeNe laser (632.8 nm) and a minimum diameter of 6 mm
this makes about 180 meters. In practice, you might not get that far but 50
meters may be feasible. (Reality enters due to the fact, that the axial
intensity distribution is assumed to be perfectly gaussian.)
One way of doing the collimation, is with a telescope consisting of two
identical plano-convex lenses. If the lenses are spaced at the double focal
length, their effect onto beam divergence will vanish. Putting them nearer
increases divergence and moving them farther apart focuses the beam. So you
can collimate the beam by fine tuning the lens distance.
Of course lens aberrations limit the performance, so weak lenses or aspheric
lenses might be desirable. Spherical aberration will be reduced by turning
the curved sides of the lenses face to face.
See the book "Lasers" by A. E. Siegmann for the details of the propagation of
laser light. (page 664 ff.)
General comments on lasers as a hobby:
-------------------------------------
We have addressed the issues involved in using common laser diodes and HeNe
laser tubes. If you are really serious and want to go further, here are some
comments on a variety of lasers.
(From: Richard Alexander (RAlexan290@gnn.com)).
How much do you like to build things? Would you prefer to assemble a bunch of
parts, or do you want to blow your own glass tubes, too? Do you have any
mechanical experience? Do you build electronic kits? Keep in mind that you
will often be working with intense light (enough to instantly damage your
unprotected eyes, and maybe your unprotected skin) and high voltages.
All laser experimenters (and optics types, too) should have a copy of
"Scientific American"'s "Light and Its Uses." [5] It gives construction plans
for a Helium Neon (you blow the glass tube yourself), an argon ion (even more
complicated), a CO2 (designed and built by a high school student, and able to
cut through metal), a dye, a nitrogen (a great first laser, but watch out for
UV light) and a diode laser (obviously, you buy the diode laser and assemble
the driver circuit from the plans they supply). They also explain how to make
holograms using visible and infrared light, microwaves and sound. There are
other projects, too. The book is getting fairly old (the HeNe dates to the
'60s), but it's still a great reference.
A nitrogen laser may be built for under $200 (maybe less than half that amount
if you are lucky). It requires no mirror alignment (since it has no mirrors).
The technology for building this laser was available to Ben Franklin, so there
is nothing too critical in it. The hazards it presents are lots of ultraviolet
light (spark discharges and laser beam), high voltage (necessary to arc across
a 1/4 inch spark gap in a nitrogen environment) and circuit etcher (the main
capacitor is made from an etch circuit board).
Once built, the nitrogen laser can drive many other projects. It can be used
as a pump for the dye laser, for example. It will light up anything
fluorescent. It is a pulse laser (10 ns) that can be repetitively pulsed (120
Hz is a likely frequency). Megawatt power is possible, but the total energy is
low (due to the short pulses).
"Electronics Now" (formerly, Radio Electronics) has a laser projects column
that started several months ago. I'm trying to think up a project I can submit
to them. They said they would welcome projects for the laser column.
Helium Neon laser tubes may be bought from many mail-order companies. I bought
one from Meredith Instruments in Arizona. They cost about $15, and the power
supply can be built or bought for about another $20. You have the option of
buying tubes with mirrors attached or not. You might want to buy the mirrors
attached, because aligning those mirrors is extremely tedious. I was given an
"A" for constructing a working Helium Neon laser from the parts in the Laser
Lab in less than an hour. The class was given two semesters to gain the
experience they needed to do that.
If you want more than one color from lasers, there are various ways to do it,
but none of them are as nice as one might like. For $3000 or so, you can buy a
Helium Neon laser that will produce laser light ranging from infrared to
blue. All you have to do is turn a dial on the back.
Laser light shows usually use argon ion or krypton lasers. These are able to
produce most of the colors of visible light, and they can also be dialed to
the desired color. However, they usually cost several thousand dollars
($40,000 is not too unusual) and require either forced air or water cooling
or a combination.
A dye laser is the usual solution to the multi-color problem. They are
inexpensive and simple. They aren't especially tunable, unless you change the
dye, although a diffraction grating can be used to tune a particular dye to
various colors. One common dye that can be used in a dye laser is the green
dye found in radiator antifreeze.
Some basic info on light show lasers:
------------------------------------
For more information on suitable light show lasers, see the Chapter: "Argon
and Krypton (Rare Gas) Ion Lasers".
(Portions from: Erik Huber (erik.p.huber@uibk.ac.at)).
I worked in a big disco as LJ - Did a lot of raves and such stuff. I also DJ
a little just for fun. The laser power you need depends on the room you have.
If you want to scan pictures you need more power. If you just use rays, you
won't need so much.
* Open air: 10 to 20 W.
* Hall or big club: 3 to 10 W (I have a 5 W laser).
* Small club: 1 W.
* Just a Room: 100 to 200 mW
The prices for such lasers look like these:
* White light, 5 W, new ZB Coherent: ca. $50,000, used $20,000, refilled old
ones for about $5,000.
* Argon (blue green) 100 to 300 mW: about $1,500.
* Laser Diodes 635 nm (bright red) 10 mW, about $150 to $250. Use these for
beams in a smoked room and it will look cool.
WARNING: Be aware that the maximum laser power level for the human eye is
about (2.5 mW)/(cm^2). Never look into the beam!
Visibility of high power laser beams:
------------------------------------
The following applies to the visibility of the beam itself (i.e., Star Wars
Light Saber style), not to its appearance then it strikes a surface.
(From: Steve Quest (Squest@cris.com)).
Visible wavelength lasers are more visible in 'plain air' if the angle of
incidence is low (you're close to the same angle of the beam) and if the power
is greater than about 5 watts. I perform an outdoor laser show using a 30 to
57 (max) watt YAG (frequency doubled to 532 nm) which is plainly visible in
mostly clear air (no need to smoke, or fog the air). When I want to do beam
effects with a 5 watt argon/krypton white-light laser, I have to fog the air
up.
Plain outdoor air has enough particulate matter to scatter a laser beam so
long as it is above 25 or so watts, thus making the beam visible. Of course,
the more power, the brighter the beam looks, but CDRH has limits, and that
limit is .9725 mw/cm^2 at 750 feet, so the days of power beam shows going all
the way to outer space and beyond is over :-(.
I used to be able to sparkle off the new moon with my YAG at full power and
full convergence. It takes some doing but you can see the sparkle from the
Sea of Tranquillity with the naked eye off the corner cube reflector, aka:
retroreflector left there in 1969 by the astronauts.
WARNING: Shooting a laser into the sky is irresponsible and highly illegal
without prior approval from the proper agencies. Airline pilots do not
appreciate being blinded! --- sam).
------------------------------------------------------------------------------
Back to Table of Contents.
Laser Information Resources
References on laser principles, technology, construction, and applications:
--------------------------------------------------------------------------
Note: The following are listed in no particular order and thus their position
in this list does not represent any sort of rating - good or bad!
1. The Laser Cookbook: 88 Practical Projects
Gordon McComb
TAB Books Inc, 1988.
Blue Ridge Summit, PA 17214
2. Build your own Laser, Phaser, Ion Ray Gun & Other Working Space Age
Projects
Robert E. Iannini
TAB Books, a division of McGraw Hill, 1983
Blue Ridge Summit, PA 17214
ISBN 0-8306-0604-1 paperback
3. Build your own working Fiberoptic, Infrared, and Laser Space-Age Projects
Robert E. Iannini
TAB books, a division of McGraw-Hill, 1987
Blue Ridge Summit, PA 17214
ISBN 0-8306-2724-3
This includes plans for a HeNe power supply as well as complete ruby/Nd-YAG
and CO2 lasers and other interesting stuff.
4. Scientific American, major articles and in particular, the monthly column,
"The Amateur Scientist". The most relevant time period will be 1960 to
1980 but there has been more recent laser and related material. The most
convenient source is [5], below.
5. Light and its Uses, (readings from Scientific American) C. L. Strong's
"The Amateur Scientist" with introductions by Jeral Walker.
W. H. Freeman And Co., articles copyright 1952 to 1980
ISBN 0-7167-1184-2, ISBN 0-7167-1185-0 (pbk).
Extensive information on how to build lasers and how to use them, as well
as info on building laser instruments. All of John Strong's (genius
experimentalist) and Jeral Walkers columns on photonic devices are in this
absolutely fabulous collection.
The book describes the construction of several types of lasers by amateurs
including HeNe, argon ion, dye, CO2, and nitrogen - all from scratch
(e.g., the HeNe and argon lasers require glassworking to fabricate the
plasma tube.) Also, some hologram, interferometer, and other optics
experiments. It is not for the absolute beginner but suitable for anyone
who has some considerable hobbyist type experience with electronics and/or
lasers.
Note: To actually construct most of these projects requires a fair degree
of skill and determination; access to some machining, glassworking, and/or
high vacuum facilities; a source of electronic, optical, and mechanical
components; and a stock of chemicals and other materials. However, much
of this can be provided without the assets of a major R&D laboratory but
will require improvisation. Nonetheless, the book makes for some very
interesting and educational reading even if you are not going to be
building anything.
6. Some older issues of Popular Electronics and Radio Electronics have
articles on how to use HeNe lasers and power supplies for them (maybe
1980 to 1989).
7. Forrest Mims' Circuit Scrapbook II
Forrest Mims
Howard Sams & Co., 1987
This book is out of print but available at some libraries. It provides
various driver circuits and a miniature laser + driver + battery built
into a very small package.
Forrest Mims has also written a number of articles on how to use and build
lasers.
8. The Laser Book - A New Technology of Light
Clifford L. Lawrence
Prentice Hall Press, 1986
A division of Simon and Schuster
New York, NY 10023
ISBN 0-13-523622-3
This book includes descriptions of many common lasers, construction, and
applications.
9. Lasers and their Applications.
Kurt R. Stehling
The World Publishing Company, 1966
Cleveland and New York
Library of Congress Catalog Number: 66-18464
10. Introduction to Laser Physics
Bela A. Lengyel
John Wyley and Sons, Inc., 1966
New York, London, Sydney
Library of Congress Catalog Number: 65-27659
If you always wanted to really understand terms like population inversion,
hyperfine transitions, and quantum efficiency, this old but solid book is
for you. Be prepared for some heavy math. However, it does include some
practical aspects of laser construction as well.
11. Introduction to Laser Physics
K. Shimoda
Springer-Verlag Berlin Heidelberg New York London Paris Tokyo, 1986
ISBN 3-387-16713-7 (2nd edition), ISBN 0-387-13430-1 (1st edition)
More heavy math, less practical information than [10].
12. The Fiberoptics and Laser Handbook
Edward L. Safford, Jr.
TAB books, a division of McGraw-Hill, 1984
Blue Ridge Summit, PA 17214
ISBN 0-8306-671-8, 0-8306-1671-3 (pbk.)
Coverage of optical fibers, lenses, lasers, applications. A potpourri of
topics, some rather sporadic but interesting nonetheless. Just take any
circuits with a grain of silicon (if you look at Figure 7.2 you will know
what I mean!).
13. Understanding Lasers
Jeff Hecht
Howard W. Sams & Company, 1988
ISBN 0-672-27274-1
Includes basic laser theory, descriptions of various types of lasers,
some applications.
14. Lasers - The New Technology of Light
Charlene W. Billings
Facts on File, Inc., 1992
460 Park Avenue South, New York, NY 10016
ISBN 0-8160-2630-0
Introduction to lasers with emphasis on applications.
15. Laser Experimenter's Handbook, 2nd Edition
Delton T. Horn
TAB books, a division of McGraw-Hill, 1988
Blue Ridge Summit, PA 17214
ISBN 0-8306-9115-4, 0-8306-3115-1 (pbk.)
Much useful information but the only actual projects uses an IR laser
diode to construct a simple communication link. And, their pathetic
attempt at a laser diode driver circuit is amusing to say the least!
(Hint: the design cannot possibly work as described.)
16. Wedding Lasers to Power Supplies
Photonics Spectra, June 1982
This is a nice article on general power supply considerations for HeNe
and (small) CO2 lasers.
17. Another place you may try is "The Bell Jar" a newsletter on high vacuum
amateur work it sometimes includes laser information. They have a WEB
site: http://www.tiac.net/users/shansen/belljar/articles.htm.
18. Some of the earlier columns of "The laser Experimenter" (1995) went into
detail on how to make light shows, and how to construct the power supplies
for the HeNe type of lasers.
19. The March 1989 issue of Radio-Electronics magazine has plans for a HeNe
power supply running on 12 VDC using a 555 timer chip and two transistors,
a relay, and a 12 V to 280 V step-up transformer.
20. The Blue Laser Diode - Gallium-Nitride based Light Emitters and Laser
Shuji Nakamura and Gerhard Fasol
Springer-Verlag, Spring 1997,
ISBN 3-540-61590-3
You may be able to find many of these items in a large public library. The old
issues of magazines are often on microfilm or microfiche.
U.S. Patents:
------------
A great deal of general information is publicly available in the form of U.S.
(and foreign) patents. With the modern computer age, searching for any and
all types of information is possible via a number of patent database web
sites. Many of these charge for full access but some are still free.
One very powerful patent search facility that is currently free is the IBM
Patent Server Site. Patents may be located by number, subject, inventor,
or boolean text, as well as more advanced criteria. All patents referenced by
a particular patent as well as all patents which reference that patent may be
instantly located. The complete patent documents including diagrams are
available at this web site for download. Text prints and CDROM copies may
also be ordered (for a small fee).
Searching on the key word 'laser' will turn up too many patents to consider.
However, narrowing this with 'semiconductor' or 'driver' will restrict the
search enough to home in on patents of interest. There will still be many
that are likely to be of interest - you can spend days (or longer) at this!
Of course, it is also possible to search for patents the old fashioned way at
your local large public library or by browsing the main patent office stacks
in Washington, DC. However, these sorts of methods seam terribly archaic in
comparison to the use of a modern patent database engine.
Usenet newsgroups:
-----------------
Newsgroups are public bulletin board-like forums for discussions of any sort of
topic under the Sun (and beyond). There are over 20,000 active newsgroups in
the USA alone and more are being created every microsecond. I know of two
newsgroups most suitable for discussion of laser related topics:
alt.lasers
sci.optics
Generally, sci.optics is to be preferred as it attracts many serious and
knowledgeable participants. However, occasionally, a question will appear
only on alt.lasers. Note: As of this writing, there has been talk of
discontinuing alt.lasers due to lack of traffic and excessive commercial
and off-topic advertisements (SPAM).
As with any type of discussion group, listen before you dive in. Get a feel
for the types of questions that are typical and do not post a reply unless
you are fairly confident of your answer! Basic questions are acceptable but
it is proper etiquette to first attempt to locate the answer by checking past
postings (by searching Dejanews and the Sci.Optics FAQ.
Laser (email) listservers:
-------------------------
Unlike Usenet newsgroups which are accessible via most on-line services and
ISPs, listservers are email discussion groups which must be subscribed to
usually by sending a special email message to the listserver host. Depending
on the charter, these may be available to everyone but some are restricted.
Once subscribed, all email sent to a specified address is distributed to all
users of the listserver group. Thus, you can elect to participate in any or
all discussions, or simply just monitor the traffic for your own interest or
research. As with Usenet newsgroups, don't jump into a discussion without
having an idea of the context - what has already transpired and then only if
you have a valid question or can contribute in a knowledgeable way to the
discussion.
The following web sites have information on the charters and how to subscribe
to some laser related listservers:
ILDA - The Laserist (The International Laser Display Association)
Laser Reflector (Amateur radio laser communications)
SPIE - Listservers (International Society for Optical Engineering)
THE web site for the hobbyist and experimenter:
----------------------------------------------
The following site is jointly hosted by Ed Edmondson Jr. and myself:
http://www.geocities.com/CapeCanaveral/Lab/3931/ (The Laser Resource Library)
"Our mission here is to provide informtion about Lasers and Laser related
equipment to the Amateur, Hobbyist, and Experimenter. Our site is the focal
and collecting point of FREE information about these wonderful light emitting
devices and their technology."
A current version of this document will always be present in some form at
this site. Currently, this is the ONLY significant information at the site
but this will change in the near future. However, while we can provide a
certain amount of information, contributions in the form of articles of any
size, schematics, and pointers to other laser related resources are most
definitely welcome on any and all laser related topics. The source will be
credited and links back to your web site may be provided where appropriate.
Other web resources:
-------------------
The following have various information and links to other laser related sites.
(Also see "Sam's Neat, Nifty, and Handy Bookmarks" for additional web sites.)
Laser safety:
http://www.creol.ucf.edu/%7elia/ (Laser Institute of America)
http://safety.nswc.navy.mil/las_saf/links.htm (Naval Surface Warfare Center)
General laser information:
http://www.misty.com/~don/laserdon.html (Don Klipstein's laser page)
http://www.rli.com/ (Lasernet - RLI, Inc.)
http://www.rli.com/tutor1.html (Lasernet laser tutorial)
http://www.achilles.net/~jtalbot/history/ (History of lasers)
http://infomatch.com/~edb/laser.html (Ed B.'s laser page)
http://www.qsl.net/wb9ajz/laser/laser.htm (Laser Reflector - Amateur radio laser communications)
http://www.qsl.net/k3pgp/!Start/opening.htm (K3PGP's laser communications/projects page)
http://pubweb.nwu.edu/~sjt064/holo/laser.html (Lasers, types, wavelengths)
http://www.ndirect.co.uk/wavefront/scioptic/faq.htm (Sci.Optics FAQ)
ftp://ftp.ee.ualberta.ca/pub/cookbook/optic/ (Laser diode PS, short laser FAQ)
http://www.holo.com/holo/ (Holocom, Inc., - Holography info and links)
Laser and optics organizations:
http://msrc.wvu.edu/leos/ (IEEE Lasers & Electro-Optics Society)
http://www.osa.org/ (Optical Society of America)
http://www.optics.org/ (Optics.org - Laser Resource Center)
http://www.spie.org/ (SPIE - Int. Society for Optical Engr.)
http://www.fys.ruu.nl/~asselber/ (Amateur Laser Constructors)
http://www.sfo.com/%7Eleoma/ (Laser & Electro-optics Mfgr's Assoc.)
Links to many laser related sites and manufacturers:
http://photonics.usc.edu/bobc/yellowpgs/photonics.html (Photonics Yellow Pages)
http://www.lasersoptrmag.com/scripts/drsrch.exeL & Os' (1997 Buyer's Guide Online)
http://www.rli.com/lazindex.html (LaserNet - RLI, Inc.)
http://members.aol.com/WSRNet/laser.htm (Lasers-Optics-USA)
http://www.splasers.com/html/link.htm (Spectra-Physics, Inc.)
http://www.sfo.com/%7Eleoma/page21.html (Laser & Electro-optics Mfgr's Assoc.)
Laser related publications:
http://www.lfw.com/ (Laser Focus World)
http://www.lasersoptrmag.com/ (Lasers & Optronics Magazine)
http://www.laurin.com/ (Photonics Spectra Online)
Laser entertainment related sites:
http://www.ilda.wa.org/ (The International Laser Display Association)
http://WWW.laser-fx.com/ (Light show and other laser info)
------------------------------------------------------------------------------
Back to Table of Contents.
Laser and Parts Sources
Suppliers for everything from $5 laser diodes to $100,000 C02 laser welders:
---------------------------------------------------------------------------
A large number of companies sell lasers, laser components, and related optics
to the hobbyist and experimenter. As with everything else these days, the
trend is toward putting their catalogs on the Web, in some cases complete
with photos of each item. There is a fairly wide range of prices so shopping
around is recommended. At least, your mouse can often to the walking.
The quality from places like Edmund Scientific is very high but you pay for
it. For many purposes, much cheaper alternatives are available.
Where actual manufacturer's model numbers are listed in the catalog or on the
web page, it is a good idea to confirm that the specifications actually do
match. Inaccuracies in catalog entries are very common (like a HeNe laser
listed as 5 mW that turns out to be only .5 mW, oops). Similarly, it would
be disappointing to say the least if you blew a visible laser diode because
the driver board actually required a regulated input when the listing claimed
otherwise :-(.
Compare prices as well. There can be a wide variation in the price of the
identical system or component among the various surplus houses or other
suppliers. Haggling (at least with private individuals) may get you a better
deal especially if you can identify lower prices elsewhere. More expensive
items may be in better condition or newer, but not always - and it may not
matter for your purposes.
A commercial supplier should know how to pack and ship fragile merchandise to
prevent damage. However, when ordering from a private individual or if you
should need to send laser parts through the mail, or via UPS, Fed-X, Airborn,
etc., packing should be done such that the box can withstand being drop-kicked
from a 10 story building. Four inches of bubble wrap or styrofoam peanuts on
all sides should be considered a minimum with adequate protection between
items as well. Stickers marked 'Fragile' and 'Do Not Drop' may just make the
package a more inviting target :-).
Then, when you receive your merchandise, make sure you actually were sold
what was expected. Confirm that it behaves as advertised. I have received
HeNe power supplies marked with reversed polarity, for example. Honest (or
otherwise) mistakes in packing and labelling do occur. And, of course, DO
NOT open the inner packaging or attempt to power an item that was shipped in
error as getting a refund may be much more difficult if the seller can
honestly claim you damaged something.
Walk-in:
-------
* Radio Shack offers a variety of laser pointers which may be suitable for
various types of simple laser experiments. While they have a variety of
electronic components as well, don't expect to find those that you would
need for serious laser power supply construction.
* Edmund Scientific has a retail store located in Barrington, New Jersey.
Complete directions are at their web site (http://www.edsci.com/). This
is a must-see if you are in the area (and worth a detour if you are not).
* Some of the places listed in the section: "Mail order - lasers, laser parts,
optics, accessories" also have retail outlets.
* Also see "Sam's Neat, Nifty, and Handy Bookmarks" for additional web sites.
Mail order - lasers, laser parts, optics, accessories:
-----------------------------------------------------
It is well worth asking for catalogs or browsing the on-line catalogs, and
getting on the mailing lists of all of these companies as they offer a wide
variety of neat, nifty, and often useful electronic, mechanical, and optical
items often at excellent prices.
Offerings include new, used, or surplus lasers and laser components. Quality
and prices may vary quite widely - check them out before ordering!
* HSC Electronic Supply (formerly Halted Specialties Co.), 1-800-4-HALTED,
http://www.halted.com/. Includes a few complete laser systems, many HeNe
tubes and power supplies (AC, DC, and kits), laser pointers, laser diodes,
and diode laser modules. The catalog at their web site may be much more
complete and up-to-date than the print version but you may have to ask about
the HeNe laser components via email since there is currently no detailed
listing of these. Their other offerings include a variety of electronic
components, small kits, scientific instruments, test equipment, PCs and
peripherals, RF and video gear, and other new and surplus items.
* Herbach & Rademan, 1-800-848-8001, http://www.herbach.com/. Includes some
HeNe tubes and power supplies, a few optical components, motors, and a
variety of other interesting and useful electronic parts. New arrivals and
closeouts are listed at web site, a quarterly catalog is available by
telephone, fax, or email request.
* High Tech Surplus. Offerings include: audio, components, computer
items, laser and optics, manufacturing/hand tools, miscellaneous,
pneumatics, power supplies, RF, robotics/automation/CNC, test equipment,
and video. Some lasers, mirrors, and other optics accessories.
* Holograms & Lasers International, 1-713-650-9204, http://www.holoshop.com/.
Holograms and holographic artwork and jewelry, surplus and pre-owned lasers
(HeNe to multiwatt argon), optical test equipment, accessories, and gadgets.
* Laser Resale, Inc., 1-508-443-8484, http://www.laserresale.com/. They
claim to be the 'largest used laser market in the USA'. On-line catalog.
* Laser Surplus Sales, 1-214-824-LASER (5273),http://www.lasersurplus.com/.
On-line catalog of lasers, powers supplies, optics, hardware, cool stuff,
and laser/optics test and measurement equipment.
* Meredith Instruments, 1-602-934-9387, http://www.mi-lasers.com/. Extensive
on-line catalog with prices for all items.
* MeshTel - Intelite, Inc., 1-310-394-3694, http://www.lainet.com/~meshtel/.
Lasers, electro-optics, equipment, and accessories.
* Midwest Laser Products, 1-708-460-9595.
* MWK Industries, 1-714-278-0563, http://www.mwkindustries.com/. Complete
on-line catalog with photos and prices of all items.
* World Star Technologies, 1-416-204-6298, http://arcos.org/laser/INDEX.HTM
Laser modules and laser pointers.
Mail order - Electronics surplus, some lasers - varies from month to month:
--------------------------------------------------------------------------
These companies offer a wide and constantly changing variety of (mostly)
surplus electronic components, modules, subassemblies, and other weird,
interesting, and sometimes useful stuff:
* All Electronics, 1-800-826-5432, http://www.allcorp.com/.
* Haltek Electronics, 1-415-969-0510.
* Hosfelt Electronics, 1-800-524-6464
* Mega Surplus, 1-314-291-7618, http://www.i1.net/~mega/.
Check out the on-line links to Silicon Valley Surplus Sources as well.
Mail order - electronic components:
----------------------------------
For general electronic components, the following will fill your needs (these
are just a sampling). Some of these companies do list a few laser diodes and
other opto-electronic components:
* Allied Electronics, Inc., 1-800-433-5700, http://www.allied.avnet.com/.
* DigiKey, 1-800-DIGIKEY, http://www.digikey.com/.
* Mouser, 1-800-346-6873, http://www.mouser.com/.
The following companies carry a wide selection of semiconductors (including
many Japanese types) and in addition have replacement parts for microwave
ovens (and other consumer electronic equipment) which may be useful for some
laser power supply designs:
* MCM Electronics, 1-800-543-4330, http://www.mcmelectronics.com/.
* Dalbani, 1-800-325-2264.
* Parts Express, 1-800-338-0531.
Also see the extensive Electronic Mail Order List at the Sci.Electronics FAQ
Web site.
Electronic and laser project parts, plans, specialized components:
-----------------------------------------------------------------
* Information Unlimited/Amazing Concepts
Inquiries: 1-603-673-4730, Orders: 1-800-221-1705, Fax: 1-603-672-5406,
Email: wako2@xtdl.com, Web: http://www.amazing1.com/
This place is definitely worth an 'at least check out their Web site'. Much
weird stuff including specialized parts (as well as plans and complete kits)
needed for the projects in the two Iannini books [2] and [3] (though cheaper
alternatives using readily available components may be available).
However, the general consensus seems to be that some (I'll be generous) of
their stuff (plans, kits, and assembled gizmos) is overhyped and/or does not
work as advertised, so buyer beware!
* Electronic Rainbow,Inc., 1-317-291-7262. Electronics, computer, phone,
and other kits, at least one 5 mW, 650 nm laser pointer.
High quality new and surplus:
----------------------------
* Edmund Scientific, 101 East Gloucester Pike, Barrington, NJ 08007-1380,
1-609-573-6250, http://www.edsci.com/.
Lasers and optics as well as many bargain priced new and surplus scientific
items. The new research quality items are expensive but there are many
reasonably prices parts, kits, and just plain old fascinating stuff.
Their catalog is a must even if you never intend to purchase anything. I
remember fascinating trips to their retail store stocked with bin-upon-bin
of interesting and unusual optical and electronic items. I do not know
what it is like these days.
* BSC Optics, 1-505-856-6863, http://www.rt66.com/swantner/. On-line
catalog with all sorts of optical research equipment, optical benches and
breadboards, mirror mounts, lens holders, light sources; optical components
including lenses, mirrors, prisms, blanks, etc.
High quality new and used optical equipment and components. Check this
company out if you are really serious about optical experiments (or need to
equip a medium size optics research lab).
Internet classifieds:
--------------------
Private individuals often post offers of laser diodes and drivers, helium
neon laser tubes, power supplies, and complete lasers, optical and mechanical
parts, and other items that are useful to the laser enthusiast. These will
most likely be found on the following newsgroups:
alt.lasers
sci.optics
sci.electronics.components
sci.electronics.equipment
sci.electronics.misc
sci.engr.lighting
A search via Deja News should turn up suitable recent postings.
Some of the (as far as I know) current offers are listed below:
* Ray (blkat@teleport.com): Visible laser diodes, modules, and drivers (power
supplies), small helium neon laser tubes and power supplies, mirrors,
motors, optics, and other interesting parts. Very reasonably priced. This
is good stuff - I have recently purchased a variety of items from him.
* Tom (tetambur@cyberhighway.net) has a large quantity (over 100) of never
used surplus HeNe laser tubes including the following types: Spectra-Physics
(1 mW, 1" x 4-3/4"); Spectra-Physics, Uniphase, Siemens (1 mW, 1" x 6"); and
Spectra-Physics model 88 (1.25 mW, 1-1/4" x 9 3/4"). 4 tubes for $25 plus
shipping (about $5 within the continental U.S.
These tubes were originally designed for barcode scanners. They have been
kept in clean storage and tested before shipping. A rare find!
* Wes (wellison@kuhub.cc.ukans.edu): All sorts of lasers from .5 mW green
HeNe tubes to 5,000 W CO2 industrial machining centers. This is the place
to go for your next laser light show (or Star Wars missile killer)!
Offers of inexpensive lasers, laser components, and other related items may
also appear from time-to-time on various laser email discussion groups. See
the section: "Laser (email) listservers".
Comprehensive list of laser diodes and suppliers:
------------------------------------------------
If you are really serious about diode lasers - not just the common $15 laser
pointer variety, check out ThorLabs and goto their Laser Search facility.
This is a comprehensive database of laser diodes of all types, styles, and
manufacturers. Searching without specifying any parameters will display the
entire list - which is quite extensive. However, it is possible to narrow the
search by manufacturer, power, wavelength, and other electrical, mechanical,
and optical characteristics.
It is also possible to obtain a print copy of their complete catalog and/or
"Thor's Guide to Laser Diodes" from their web site or by writing to Thorlabs
at the address shown in the section: "Some laser manufacturers".
Some laser manufacturers:
------------------------
See the section: "Other web resources" for links to lists and directories of
manufacturers of lasers, optics, systems, equipment, and components.
* Aerotech Inc.
101 Zeta Dr.
Pittsburgh, PA 15238
Phone: 1-412-963-7470.
Web: http://www.industry.net/aerotech
HeNe lasers, power supplies, positioning mechanics, linear motors, rotary
motors and drives, motion controllers, and laser interferometers. Note:
I do not know if Aerotech still manufacturers laser components.
* Coherent, Inc. Laser Group
5200 Patrick Henry Drive
Santa Clara, CA 95054
Phone: 800-537-3786
Web: http://www.cohr.com/clg/clg_home.html
CO2, tunable-dye, ion, CW, YAG, YLF, ultrafast, diode and diode-pumped
solid-state lasers for science, medicine, and industry.
* Fermionics, Inc.
4555 Runway Street
Simi Valley, CA 93063
Phone: 1-805-582-0155
Fax: 805-582-1623
Email: Fermionics@worldnet.att.net
InGaAs photodiodes, and InGaAsP lasers for fiberoptics, and HgCdTe detectors
for imaging and sensing applications.
* Ion Laser Technology Inc.
263 Jimmy Dolittle Road
Salt Lake City, UT 84116
Phone: 1-801-537-1587.
Argon and mixed gas lasers and components.
* Laser Diode, Inc.
4 Olsen Avenue
Edison, New Jersey, 08820 USA
Phone: 1-908-549-9001
Fax: 1-908-906-1559
Fiber optic transmitter and receiver products, GaAs pulsed lasers and GaAs
high power CW lasers.
* LaserMax, Inc.
3945 Winton Place, Building B
Rochester, NY 14623
Phone: 1-716-272-5420
Fax: 1-716-272-5427
High quality diode laser modules.
* Laser Physics, Inc
3673 W. 1987 S.
Salt Lake City, UT 84104
Phone: 801-975-2668 Fax: 801-975-7011
Web: http://www.laserphysics.com/
Air cooled argon and krypton ion lasers.
* Lexel Laser, Inc.
48503 Milmont Dr.
Fremont, CA 94538
Phone: 1-510-770-0800.
Web: http://www.lexellaser.com/
Ion, dye, ultrafast continuous wave and mode-locked Ti:Sapphire laser
systems.
* Liconix
3281 Scott Blvd.
Santa Clara, CA 95054
Phone: 1-408-496-0300.
Web: http://www.liconix.com/
UV and Blue lasers based on HeCd and diode pumped solid state technologies.
* Melles Griot (HeNe laser headquarters - other contacts at their web site.)
2251 Rutherford Rd.
Carlsbad, CA. 92008
Phone: 619-438-2131
Fax 619-438-5208
Web: http://www.mellesgriot.com/MG-HOME.htm
HeNe lasers, laser diode systems and sub-assemblies, optics, accessories,
components, coatings, much more.
* Metrologic Instruments Inc.
90 Coles Road
Blackwood, NJ 09012
Phone: 1-800-ID-METRO
Fax: 1-609-228-6673
Web: http://www.metrologic.com/
HeNe and diode lasers and components, educational lasers/kits, optics, bar
code scanners.
* Opto Power Corporation
3321 E. Global Loop
Tucson, AZ 85706
Phone: 520-746-1234
Fax: 520-294-3300
Web: http://www.optopower.com/
High-power diode lasers, diode laser systems and integrated stacks, and
fiber-coupled diode lasers.
* PMS Electro-Optics
1855 South 57th Court
Boulder, CO 80301
Phone: 303-443-7100
FAX: 303-449-6870
TWX: 469-143 or 910-940-5891
* Power Technology, Inc.
P.O. Box 191117
Little Rock, AR 72219-1117
Phone: 501-568-1995
Fax: 501-568-1994
Web: http://www.powertechnology.com/
Diode lasers and modules, accessories, diode pumped Hd:YAG lasers, HeNe
power supplies, more.
* Spectra-Physics
Mountain View, California
Phone: (Sales) 800-SPL-LASER
Phone: (Service) 800-456-2552
Email: sales@splasers.com
Web: http://www.splasers.com/
Lasers and laser systems, optics, and optical instrumentation for OEM,
science, and industry.
* Thorlabs, Inc.
75 Mill Street, P. O. Box 366
Newton, NJ 07860-1453
Phone: 201-579-7227
Fax: 201-383-8406.
Web: http://www.thorlabs.com/
Optical components, laser diodes, laser diode drivers, fiber optics. Web
includes on-line catalog and laser diode search facility by manufacturer,
power, wavelength, etc. (Searching with no parameters specified displays
all available laser diodes - and there are a huge number of them! Detailed
specifications are then just a mouse click away.)
* Uniphase Corporation
163 Baypointe Pkwy.
San Jose, CA 95134
Phone: 1-408-434-1800.
Web: http://www.uniphase.com/
Laser subsystems for biotechnology, industrial process control, measurement,
graphics and printing, and semiconductor equipment, 980 nm pump lasers and
related products. HeNe lasers and laser components.
------------------------------------------------------------------------------
Back to Table of Contents.
Forward to Diode Lasers.