hello people, I need quick help I got the differentiation of output signal in terms of a sum of delta functions. all I wanna know is how do I find out which one is the impulse response. Thank you

@uhoh I wonder if laser diodes would count as LEDs?..

Having said that, I don't know who was the first lander with a laser diode.

Raman spectrometers... Laser rangefinders... Opto-isolators... sample inspection?

@NickAlexeev interesting point! I think a laser diode will often change to super-luminescent LED mode if the bias is lowered a bit.

@W5VO ya that's right many if not all of those are on Mars now. I don't know about semiconductor-based laser-based range finders on the surface though, but DPSS lasers abound in space and the "DP" is for diode laser for pumping the Nd:YAG.

For range finding by objects on surfaces of bodies, usually stereo-imaging is used. However several orbiters have probably crashed into various bodies, so their diode-pumped lasers are now on surfaces! This is a good point, I'd never thought about it!

If you didn't specify planets, some of the asteroid missions would almost certainly have some. Indication LEDs are probably somewhere in most newer designs, but that's pure speculation.

@W5VO yep, so the challenge for this question is to go back in time and find the first instance. You are right, I did specify planet in the title, but I opened it up to "astronomical body" in the restatement of the question in the body of the post. I should probably resolve that.

But think the answer will be so far back in time that a planet will turn out to be the answer.

@W5VO done, thanks!

I was hoping it was the DSKY on Apollo, because that would be cool, but the DSKY display is an EL type.

@uhoh my guess: in an optocoupler or optosensor somewhere?