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IR Filter

jetson333

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Why does it matter so much if a laser has an IR filter? Would a 5mW without an IR filter be considered unsafe?

Thanks for any help.
 

NairB

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jetson333 said:
Why does it matter so much if a laser has an IR filter? Would a 5mW without an IR filter be considered unsafe?

Thanks for any help.
Hi jetson333..... Lets look at why there is an IR filter in the first place......

An Infrared (808nm) laser diode produces light in the infrared (invisible to the human eye) spectrum, which is fired into a focusing lens that sends the laser beam through an ND (neodymium yttrium vanadium oxide) crystal. This increases the light's frequency to 1064nm, which is still in the infrared (IR) laser spectrum.
The KTP (potassium, titanium, phosphorus) crystal makes the final conversion into green light, which is the beam color that is most visible laser to the eye sight.

The visible beam then goes through an infrared filter to help block any stray IR as a result of the conversion and finally the green light is focused once again as it leaves the front of the laser.

So whether its 5mW or 50mW these stray IR are extremely harmful to your eyes as they tend to be of higher mW, say as much as the original 200mW of 808nm the diode is pumping out which as you can see is much higher in power than the actual green beam itself. There are also stray 1064nm IR present too.

Lots of ebay lasers are being advertised as 95mW+ greenies but they are actually 10 - 15mW greenies with no IR filter......so very dangerous high powered invisible IR radiation could go into peoples eyes without them knowing :-/

Hope this helps.
 




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