Temperature measurement with a Pyromter

[long qi]

I want to measure the temperature of a metal surface surrounded by glass with a near infrared pyrometer(1.45 micron to 1.7 micron). I am not sure the influence of the glass on the measuremental accuracy. You know the infrared radiation may be absorbed by the glass to make uncertainty.

Please give me some advices on this issue.

 

[Redbelly98]

Welcome to PF.

Depending on the type of glass, the transmission is likely 90%, give or take a few %, over that range. That means the reading will be about 2% to 4% lower than the actual temperature, on an absolute (eg. Kelvin) temperature scale. (Based on the T⁴ dependence of radiation.)

Do you have a sample of the same glass, without the metal in it? You can test the glass's effect by taking a reading, then hold the test glass in front of the pyrometer and take another reading. See how much the reading drops, and add that number to the original reading.

 

[Andy Resnick]

I've done similar measurements using infrared cameras. It's not a clean measurement- what kind of accuracy are you going for?

The best solution is to 'calibrate' the sample using a thermocouple to obtain an effective emissivity.