IR collimaing lens ?

[trueHOUSE]

is there a lens which i can use to collimate an IR light easyer?

 

[murrat]

I think there is no special lens to collimate IR (I think you are talking about 808nm)
You can use the same lens that is designed for 532nm light.

 

[BlueFusion]

Well you _can_ but due to refraction being different with different light wavelengths you need a much stronger lens or the same one with extreme adjustment.
Deep IR is stopped by glass but not reasonable wavelengths like 808, 1064nm.

 

[steve001]

look here http://www.laserpointerforums.com/forums/YaBB.pl?num=1186613419

 

[likewhat]

Well you _can_ but due to refraction being different with different light wavelengths you need a much stronger lens or the same one with extreme adjustment.
Deep IR is stopped by glass but not reasonable wavelengths like 808, 1064nm.

The index of refraction doesnt change much over the visible for any lenses that are common or they would choose a different material to make the lenses out of to avoid horrible chromatic abberration. You can see in this link

http://www.mellesgriot.com/products/optics/mp_3_1.htm

that BK7, a popular glass to make lenses out of, the index only changes by 0.5% from 532 to 808. That difference wouldnt really call for extreme adjustment, an adjustment of around 0.5% would probably do it.

 

[BlueFusion]

It mainly comes from the fact (that is, 532 vs 808) that the 532 is already fairly collimated after leaving the crystals whereas the 808 is divergent as hell.

 

[amkdeath]

808 is divergent as hell.

;D ;D


do the 808nm aixiz lasers (pre-installed in modules) on their website have 808nm lenses? or just the normal acrylic...

 

[JLSE]

I bought some 808 1watt, and it is the hardest ive had to deal with for focus. I have found that two lenses are required to get a decent beam. The first lens to quickly spread the light (conical), and the second to render it down. Problem is two lenses take away some power but it will give you better distance. The diode on its own gives a big flat bar 4ft wide at 5ft. This has been by far the toughest to focus.

 

[likewhat]

Yeah, you probably need to use a short focal length cylindrical lens to stop the fast axis from diverging then use a regular lens after it to focus it down.

 

[trueHOUSE]

yes wannaburn i found that too but i don't have small lenses without ir filter i have only 3 lenses without ir filter but they're something like 4-6 cm d