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Extrema Keychain Green Laser Pointer, retail $19.99 (http://www.kaidomain.com...)
Manufactured by (Unknown)
Last updated 11-05-12

(In reference to the envelope I received from KAIDomain at 2:43pm PDT on 08-22-07):
{sung like the Foreigner song "Feels Like the First Time"}

This is a green DPSS (diode pumped solid state) laser pointer that fits on your keychain!!! This is the smallest green beam laser I've come across to date (08-22-07) (the previous small record holder was this one).

It comes in an all-metal body, and feeds from three LR44 button cells - the ubitiquous "laser pointer battery".


To use the laser pointer, 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 pointer back off. Yes, it really is as easy as that.

To change the batteries in your green laser pointer, 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 92.5mA on the included LR44 button cells, using the 400mA scale on my DMM.

This is a laser pointer, not a flashlight. So I won't throw it against the wall, stomp on it, try to drown it in the toylet bowl or the cistern, run over it, swing it against the concrete floor of a patio, bash it open to check it for candiosity, fire it from the cannońata (I guess I've been watching the TV program "Viva Pińata" too much again - candiosity is usually checked with a scanner-type device on a platform with a large readout or with a handheld wand), send it to the Daystrom Institute for additional analysis, or inflict upon it punishments that flashlights may have inflicted upon them. I almost never beat, hit, throw, stomp on, or otherwise attempt to destroy lasers or other products which lase, because of their inherent delicacy. Therefore, 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". Usually, there is a filter that removes NIR and IR (near-infrared and infrared) laser radiation from the pump diode and the crystals, but this filter does not appear to be present in this laser.

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.
Yes, I checked with an oscilloscope in order to determine this (the photovoltaic cell I use for this test does respond to the 808nm NIR laser radiation because I can see the oscilloscope's display visibly "jump" when the cell is irradiated with this laser).

Note the lack of laser radiation in this "beam photograph".
Actually, a feeble green spot can be seen; the red arrow points to it.
Power output measures 293.23µW ("µW" = microwatts) on a laser power meter.
This value also includes the 808nm component (the meter was set to read this wavelength); visible radiation probably peaks at ~7µW.

Photograph of the laser's "business-end" while it was on.
Note the purplish-white color; indicative of 808nm NIR radiation from the pump diode.

Beam terminus photograph on the test target at ~12".
Taken on 10-30-12.

Beam terminus photograph on a wall at ~8 feet.
Taken on 10-30-12.

Spectrographic analysis
Power output analysis.
Tops out at 32mW on a LaserBee 2.5W USB Laser Power Meter w/Thermopile.
Most of this value is NIR radiation from the pump diode, not the visible green radiation that would be hoped for.

Spectrographic analysis
Another power output analysis; this time taken on a Sper Scientific Pocket Laser Power Meter # 840011 After doing the necessary multiplication as indicated inside the LPM's lid, this laser tops out at 744µW (that's MICRO watts); the NIR filter from my Yellow (593.5nm) DPSS Portable Laser was placed between this laser's aperture and the sensor on the LPM.
However, most of the time it appears to output somewhere between 8µW and 16µW of green radiation.

Spectrographic analysis
Spectrographic analysis of this laser.
I checked for IR, as shown below.

Spectrographic analysis
Same as above...{alarm sounds} {female computer voice} INPUT OVERLOAD!!!*
Let's try this again...same as above, but deliberately overloaded to check for the pump diode's 808nm laser line.

Actually, I did not need to overload the instrument at all, because no green
laser radiation was produced when this spectrum was taken.
As you can see, no IR filtering is evident.

Spectrographic analysis
Repeat spectrographic analysis of this laser.

Spectrographic analysis
Spectrographic analysis of this laser; spectrometer's range narrowed to a band between 790nm and 815nm to pinpoint the wavelength of its pump diode, which is exactly 807.00nm.

Spectrographic analysis
Repeat spectrographic analysis of this laser (10-30-12).

Spectrographic analysis
Repeat spectrographic analysis of this laser (10-30-12); spectrometer's response narrowed to a band between 530nm and 535nm to pinpoint wavelength, which is 532.669nm.

USB2000 spectrometer graciously donated by P.L.

Test unit was purchased on the KAIDomain website on 08-07-07, and was received on the afternoon of 08-22-07.

* From the Star Trek TNG episode "Home Soil".

Product was ***VERY LIKELY*** made in China.
A product's country of origin really does matter to some people, which is why I published it on this web page.

Since the product was defective right out of the package rather than failing during or after testing, I will not issue that dreadful "Zero Stars. Whip Out Your {vulgar term for male uranator/inseminator; rhymes with 'wrecker'} or Run to the Lavatory, Sit Down, and Uranate On It!" rating. I will however, put the "" icon next to its listings on this website.

UPDATE 00-00-00:



    PRODUCT TYPE: Keychain-style laser pointer
    LAMP TYPE: DPSS diode laser/NdYVO4/KTP crystals
    No. OF LAMPS: 1
    BEAM TYPE: Very narrow spot; it's a laser, remember?
    SWITCH TYPE: Pushbutton momentary on/off on barrel
    CASE MATERIAL: Metal; possibly brass
    BEZEL: Metal; has aperture (hole) for laser beam to emerge
    BATTERY: 3x LR44 button cells
    WATER- AND PEE-RESISTANT: Very light splatter-resistance at maximum
    ACCESSORIES: 3xLR44 button cells, swivel, "lobster claw" clasp, hinge-lidded storage case
    SIZE: 1.5cm D , 7.5cm L
    WEIGHT: 50g (1.750 ox.) incl. batteries
    WARRANTY: Unknown/not stated


    Product was defective upon receipt, so it cannot be rated.

Extrema Keychain Green Laser Pointer * http://www.kaidomain.com...

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