thermopiles/IR sensors

I am looking for a way to optically measure temperatures in a very small space. I have looked at the so-called IRt/c's and everything I have seen is to large. I have a gap of about 1mm I need to insert something into. Just to keep it interesting, I need to "look" at a 90 deg angle to the direction of insertion. In other words, I need to look at the wall of the channel I am inserting the sensor into. I thought maybe there was a device that would use a fiberoptic fiber to transfer the light back to an IR sensor, but so far I haven't found it. Any suggestions?

Have you checked with Omega.com? I had a similar problem, and I remember that they had several types of infrared sensors. They are limited as to what temperature the sensor head can withstand. As I remember, it is about 300 degrees F max, even though you can measure up to 2200 degrees.

Good luck finding something for your application! I have used IR sensor from Raytek but I don't remember how small of an area it can measure. I think the SX series might go that low (1 mm) but I don't remember for sure. It did have a laser aiming light and software for recording and monitoring. Here's their website: Raytec Thermalert

Why not use a simple thermocouple wire only one and use the tube as the other.
we have used it in a piston just drill holes and put wires in.

IR works just like light, a polished stainless mirror will work fine for looking around corners, the only thing you have to do is keep it at the same level of cleanliness as when you calibrated it