Interesting opto device

Maybe its a Laser Diode (or high pwr LED?), thermistor for temp measurement feedback, peltier to manage temp. Where did you find it?

Maybe a long-wavelength (thermal) IR detector. One of those lead titanate things or something. Out of an old Sidewinder maybe?

John

Yup, my money would be on an IR detector as well - lead selenide (PbSe) or lead sulfide (PbS) is what you're thinking of, I think :) Both are frequently used with cooling, and need monitoring of the temperature since their peak sensitivity depends on temperature. Exactly what it's from is difficult to say, since they're used all over the place, and 12188 doesn't seem to give any useful hits.

I could have sworn I was thinking of lead titanate.

John

Lead titanate and lead zirconate-titanate (PZT) are both ferroelectrics that are used for pyroelectric IR detectors, but they're generally used uncooled.

Lead sulphide and lead selenide are very low-barrier semiconductors that at one time were the best available IR detectors in the 2-3 um band (where Ge craps out). They work best cooled, because they're so leaky (they also have other problems e.g. a strong memory effect, like CdS and CdSe in the visible).

Based on the TE cooler, It might be a lead salt, or possibly mercury cadmium telluride. You can tell by whether it responds to thermal IR or not.

It has a certain hand-made look to it, so it might very well be somebody's brilliant idea that never worked properly.

Cheers,

Phil Hobbs

...

I suggest a germanium or GaInAs avalanche photodiode for ultrasensitive infrared detection (astronomy, microanalysis etc - but lately the hot market is single photon detection down optical fibres for quantum encryption). Normally used cooled - sometimes with liquid N2 - have a look at the J16TE series of widgets from Judson Technologies:

These have an integrated TE cooler too. What I think you have is a prototype version of one of their things, or a one-off remarkably like it made by some researcher in a lab (there are various mad scientists locked up in labs around the planet trying to improve the materials used in these photodiodes for their PhD's).

Having identified the device, we need to apply Rule 34* to find out what it's REALLY used for.

Lots of low volume production stuff has that same look about it. That makes me think that John's idea (an IR detector for a Sidewinder or something similar) might be right.

Unlikely ... looks nothing like the ones I've used. Both the connections to the active part appear to be on the same side (left-right as opposed to front-rear). Also, the facing surface is non-uniform. Since avalanche photodiodes are usually made by evaporating some conductor onto the wafer the front surface should be near mirror-like unless it has been damaged through sparking. Finally, the OP said that it appears to be unpolarized and non-photovoltaic, which doesn't really sound like a photodiode :)