Keychain Green Laser Module, retail $49.95
Manufactured by (Unknown)
Last updated 01-12-11

(In reference to the envelope I received from an Ebay seller around 2:00pm PST on 12-12-05):
{sung like the Foreigner song "Feels Like the First Time"}
Feels like a flaaaaaash-liiiight...feels like a FL

BREAK IN 50276


Let's try that soon as I started to open the package, I *knew* it wasn't a flashlight...

Feels like a laaaaaa-sssser...feels like a LAAAAA-aaaaa-ssser!!!
Feels like a laaaaaa-sssser...feels like a LAAAAA-aaaaa-ssser!!!

This is a green DPSS (diode pumped solid state) laser module that fits on your keychain!!! This is, by far, the smallest green beam laser I've come across to date (12-12-05).

It comes in an all-metal body, and feeds from three LR44 button cells - the ubitiquous "laser pointer battery". It's a very hungry laser module though, so it's good that so many extras were included.


To use the laser module, just aim it at something you wish to point out, and press & hold down the button on the barrel for as long as you need the laser spot. Release the button to turn the laser module back off. Yes, it really is as easy as that.

To change the batteries in your green laser module, unscrew and remove the tailcap, throw it in the {vulgar term for feces}bowl, yank that silver handle on the front of the cistern down, and flush it away...O WAIT!!! YOU'LL NEED THAT!!! So just set it aside instead.

Tip the three used LR44 cells out of the barrel and into your hand, and dispose of or recycle them as you see fit.

Insert three new LR44 cells into the barrel, button-end (-) negative first. This is the opposite of how batteries are installed in most flashlights, so please pay attention to polarity here.

Screw the tailcap back on, and be done with it.
Aren't you glad you didn't flush away that tailcap now?

Current usage measures 152mA on the included LR44 button cells.

Published battery life is just ten minutes a set ; it's a good thing that four spare sets are included in addition to the set already installed.

This is a laser module, not a flashlight. So I won't throw it against the wall, stomp on it, try to drown it in the toilet bowl, run over it, swing it against the corner of a concrete stair, or inflict upon it punishments that flashlights may have inflicted upon them. So this section of the laser's web page will seem a bit more bare than this section of the web page on a page about a flashlight.

Green diode lasers are a lot different than those common red lasers you see all the time.

In a 640nm red laser pointer, there's a red-emitting diode and a lens to collimate (focus) the beam.

In a 532nm green laser (pointer or larger size), there's a BIG infrared laser diode that generates laser light at 808nm, this is fired into a crystal containing the rare-earth element "neodymium". This crystal takes the 808nm infrared light and lases at 1064nm (yes, deeper in the infrared!). This 1064nm laser light comes out of the NdYV04 (neodymium yttrium vanadium oxide) crystal and is then shot into a second crystal (containing potassium, titanium, & phosphorus, usually called KTP) that doubles the frequency to 532nm - the bright green color you see. This light is then collimated (focused) by a lens and emerges out the laser's "business end". Just before the lens, there's a filter that removes any stray IR (infrared) rays from the pump diode and the neodymium crystal. You don't want that stuff in your green beam, trust me. :-)

This is why green diode lasers are so much more expensive than red ones. Lots of itty bitty parts, and they all need to be aligned by hand. If the polarisation is "off", one or both crystals need to be turned. With red diode lasers, you just slap in the diode and slap a lens in front of it.

This laser is not water-resistant, so please be extra careful when using it around sinks, tubs, toilets, fishtanks, pet water bowls, or other places where water or water-like liquids might be found. And you'll probably want to cover it up or otherwise get rid of it (such as by putting it in a pocket or bag) if you need to carry it in rainy or snowy weather.

The laser radiation is CW (continuous wave), not pulsed.

Beam photograph at ~12".
Beam is not white like this photograph makes it appear.

Beam is also a lot smaller than it appears; the
beam image bloomed significantly when photographed.

Measures 5.505mW on a laser power meter specifically designed for that purpose.

Beam photograph at ~15'.
Beam is not white like this photograph makes it appear.
Beam is significantly smaller than it appears;
the beam image also bloomed when photographed.

Those rectangular graphic things near the center are marquees from:
Cinematronics ''Star Castle''
Midway ''Omega Race''
Williams ''Robotron: 2084''
Gremlin/Sega ''Astro Blaster''
Atari ''Tempest''
Williams ''Stargate''
Williams ''Joust''
Venture Line ''Looping''
Sega ''Star Trek''
Midway ''Gorf''
upright coin-op arcade video games from the early-1980s.

That red thing is from an American DJ Laser Widow.

I do not have an outdoor laser testing facility at my new location,
so I will not be able to provide any distance photographs.

Spectrographic analysis
Spectrographic analysis of this laser.

Spectrographic analysis
Spectrographic analysis of this laser; spectrometer's response widened to pinpoint NIR laser line from the pump diode.
As you can see, none is detectable -- this shows that the IR filter in this laser is doing a fantastic job!!!

USB2000 spectrometer graciously donated by P.L.

Test unit was purchased on Ebay on 12-08-05, and was received on the afternoon of 12-12-05.

Because this unit measures just in the CDRH Class IIIb range (5.505mW), I should call it a "module" on this web page, not a "pointer".

UPDATE 01-08-06:
I noticed something rather disturbing a few moments ago (1:11pm PST): as I was looking for the clasp for my keys so I could reattach them to my EDC bag, I noticed the tailcap of this laser had unscrewed itself approximately one turn. This gives the potential loss of the laser if it is not Caught in a Mosh (o o, there I go thinking about the heavy metal band Anthrax again!) - caught in time. For this reason, I have decided to derate it by star.

UPDATE 01-15-06:
I noticed this morning that the metal tip of the laser had become unscrewed and fell off who knows where.
Kiss another star goodbye.

UPDATE 01-15-06:
No, you aren't seeing things.
Yes, a same-day update.
I found the metal tip for the laser outside the back door early this afternoon (12:24pm PST today); I have screwed it back onto the unit so I once again have a whole laser, instead of one missing a part. But I have - for the time being anyway - retired the laser from keychain duty and placed it on the front of my computer keyboard - resting against the sides of the F7, F8, and F9 keys to be specific.

Bright green laser beam.
Smallest green laser I've come across
Feels good in the hand; is also rather hefty.
No beam artifacts - none that I've been able to detect anyway.
Lots of extra cells come with it if you purchase on Ebay

Not waterproof or submersible - but most modules aren't. Will not figure into my rating.
Consumes a lot of power, so you'll be going through batteries if you use it a lot.
Battery lifetime is estimated at just ten minutes a set.
More delicate than directly-injected diode laser pointers/modules.
Just a hair over the Class IIIA limit it is labelled for.
Can become unscrewed and potentially fall off your keychain.

    PRODUCT TYPE: Keychain-style laser module
    LAMP TYPE: DPSS diode laser/NdYVO4/KTP crystals
    No. OF LAMPS: 1
    BEAM TYPE: Very narrow; it's a laser, remember?
    SWITCH TYPE: Pushbutton momentary on/off on barrel
    BEZEL: Metal; has aperture (hole) for laser beam to emerge
    BATTERY: 3x LR44 button cells
    ACCESSORIES: 15 batteries, spring-loaded "lobster claw", split ring, swivel
    WARRANTY: Unknown/not stated


    Star Rating

Keychain Green Laser Module *

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