Measuring IR laser output?

[tac57]

For a bit of further info for those that may not understand the science behind laser safety:

The reason the IR lasers have a lower max power limit is due to the fact that they are invisible to the human eye (which is why they're great for night ops with NVG's). With a visible laser such as a ~650 nm red or ~532 nm green (which are the two most common "airsoft" laser wavelengths), as long as the power is below 5mw, the laser is considered "eye safe" in that your blink reflex will protect you from retinal injury in most situations (you blink before the laser has had enough time on the retina to cause major injury).

This is NOT to say these lasers are 100% eye safe however, since if the unit is misused retinal injury could still result in some rare circumstances.

You also get into the issue of the chinese lasers not having the proper power output as stated on the label. Often these units will say they put out 5 mw, but they may put out 10-50 mw of mixed green and IR laser radiation.

This is due to how green lasers work, a system called DPSS or diode pumped solid state. Basically you start with a high power (around 100-200 mw) 808 nm IR diode, which pumps a Nd:YAG crystal producing 1064 nm IR radiation. The 1064 nm light then is "frequency doubled" through a KTP crystal in the laser module producing 532 nm green light. This green light (the laser beam) is filtered through an IR filter to screen out any stray IR light that would have made it through, and therefore the laser beam will be only 532 nm (green) laser light.

The problem is that most chinese green DPSS lasers do not have an IR filter, and therefore a "5mw" laser pointer or peq box may actually be putting out for example 50 mw -> ~5-10 mw of green and 40-45 mw of IR.

Therefore the blink reflex will protect against a lower power green laser (under 5 mw), but if there is no IR filter the person can still be exposed to IR laser radiation which will be invisible. No blink reflex will kick in and retinal damage can result.

That is why the IR lasers have such a low max power - the blink reflex will not kick in to protect your eyes, and thus the power output of the laser must be low enough that if a person was exposed no retinal injury would result.

FYI: Most of this is oversimplified.

If your a laser safety officer or otherwise have proper knowledge of lasers feel free to rip this to shreds and more importantly give the correct answer.

[Viperfish]

So how did it do in the test?

[Cobrajr122]

Originally Posted by Viperfish

So how did it do in the test?

well, seeing as he has not posted up results, the test has not been done yet....

[Viperfish]

Originally Posted by Cobrajr122

well, seeing as he has not posted up results, the test has not been done yet....

Or it tested over 9000 and he is using it to build a death ray to hold the world ransom....