What is the longest wavelength of laser light you have seen?

[paul1598419]

That is why I qualified my statement first by stating that I only do this in holography situations, and second by using the square of the distance inverted being the only time I do it. It is also very easy to measure the light at a white card before looking at the light itself. Diodes won't work for refection holography, so that only leaves gas lasers ( for me). And their power is far below class IV lasers ( for me).

 

[Alaskan]

Yea, I understood. Holography must be a cool thing to do, I think everyone loves holograms.

 

[Sigurthr]

Diodes won't work for refection holography, so that only leaves gas lasers ( for me).

Step the presses. Where is this gem of info from!? I had attempted doing reflection holography with an Integraf kit a few years back, and they assured me a temp stabilized diode would work, so that's what I used. I didn't get a single good hologram out, and chalked it up to lack of a vibration isolated optical bench. What property in particular precludes diodes from reflection holography?

 

[lazeristasUVISIR]

Worked with these lasers:
10000 nm (CO2) - unless it was marking, no way to say there is a beam.
2800 nm (a SS laser, forgot crystal and doping) - would leave a nice dark spot on a thermal paper otherwise invisible.
2000 nm (Tm:YAG) - same thing.
1064 nm (Nd:YAG) - sometimes some green photons would reach my eye. Later got to know that a SH can be generated on surfaces.
850-980 nm (laser diodes) - invisible
785-830 nm (laser diodes) - reddish spots.