Infrared laser pointers?

[Alaskan]

I've seen what I believe are not faked youtube videos showing IR sources in the sky and I have no doubts they are not caused by the weather, what ever they are. But what will an IR laser do for you with that?

 

[rstevens]

I've seen what I believe are not faked youtube videos showing IR sources in the sky and I have no doubts they are not caused by the weather, what ever they are. But what will an IR laser do for you with that?

I was planning on doing an experiment with an IR laser as well as a regular laser pointer, and aim it at the lights, just to see what happens, Im not sure if IR would make a difference or not, just wanted to have both on hand to test at the same time.

Although like I said above, from reading more on this forum, I am a newbie on the workings of lasers and IR, so Im going to study up before attempting to try this.

I was talking about this with a friend earlier and she warned me against even attempting to do this, not so much due to the use of lasers, but said signalling it may not be a good idea.

 

[Alaskan]

IDK, but I wouldn't worry about getting into trouble with a fairly high divergence low to medium power infrared laser when at a long distance away.. Also, I doubt someone will come after you for it unless a law enforcement chopper with night vision which could see IR pointed at it, believing you are trying to mess with them. Have fun, I don't expect to hear you were arrested for it, but if you follow the letter of the law, we are not supposed to point IR lasers at anyone, so make sure it isn't an aircraft, animal or person. Although, above a certain power level you shouldn't do it at all, especially if low divergence. Don't ask me what power level, I don't know, but it will be a hazard if too much power when the divergence is low, depending upon the distance.

 

[Blarg King]

I would definitely get a good pair of IR blocking goggles too. They aren't that expensive and they could very well end up saving your eyes. While pointing up at the sky is generally less risky, if some IR ends up scattering off some fog or particulate in the air you could get some IR back in your eyes without even knowing.

 

[Alaskan]

Good point, if you are going to be using this pointer inside, or where it can either reflect off of something, or accidentally hit yourself or someone else in the eye, laser protection goggles or glasses are a must for everyone.

If you want to do this, here are some IR laser pointer offerings from Jetlasers.org

808 nm: https://www.jetlasers.org/pl-e-pro/...nish-silver/49-goggles-no/42-power_levels-35w

980 nm: https://www.jetlasers.org/pl-e-pro/..._expander-no/49-goggles-no/37-power_levels-2w

1064 nm: https://www.jetlasers.org/pl-e-pro/...nish-silver/49-goggles-no/36-power_levels-15w

Near-IR (near to the visible spectrum) 780, 808, 980 and 1064 nm all have low atmospheric loss, but that isn't necessarily true through clouds. Here's a graph showing atmospheric transmittance through clear sky:


Click on the image for larger size. The dark lines are areas of higher loss.

I added the red lines to this chart for the more common laser wavelengths (except 1025, that isn't common) which have low loss through clear atmosphere. Loss is very low at 780 and 1064 nm, not too bad at 808 nm which is a wavelength you can find high power laser diodes at fairly inexpensively, although usually relatively high divergence at 808 nm when high power, but that can be solved to reduce the divergence to 1.5 mRad or lower using a relatively long focal length large diameter collimation lens (Long FL to our common laser pointer lenses of 8 mm & shorter focal length). Jetlasers infrared pointers have close to 2 mRad divergence which isn't very good compared to many DPSS visible spectrum laser pointers at 1.5 and lower, but it should work fine for what you want to do.

If you buy a 10X beam expander from them, then the divergence is very good and far tighter than most laser pointers. If using their beam expander at IR you might need a camera to see the beam with to be able to center it properly on the pointer, their design allows so much adjustment it can easily be off to the side too much cutting off half of your beam or more. FYI, cameras with the IR filter removed can pick up 780 and 808 nm fairly well, but not 980 or 1064 nm. The sensitivity of most consumer cameras to 980 & 1064 nm, even with the IR filter removed, is a small percentage compared to 808 nm and shorter into the visible range below 700 nm.



Note: The wavelength of infrared that thermal imaging cameras detect is 3 to 12 μm, and differs significantly from that of night vision, which operates in the visible light and near-infrared ranges (0.4 to 1.0 μm).

 

[hoo7h]

Man I can't tell what you can or cannot do but if you buy one please be very careful with it and protect your eyesight with suitable safety goggles. An invisible overspecs laser may reflect on shiny surface and hit you in the eye and damage your vision and you probably won't realize it till its too late.. You probably already know that but I just wanted to make sure. Good luck on your experiment and keep us posted if the things contact you back I guess lol.