hello everyone I would like to know if it is possible to have an accurate long distance body temperature sensor (2.5m)? if yes advise me a model because I would like to make a long range infrared thermometer ... for my end of studies project. By the way I am a novice and studying computer systems and networks license 3 in Cameroon. thank you
Please define the needed field of view for the sensor and what accuracy you need. Have you found commercial devices that meet you needs?
Paul
bluejets:
This...?
Two problems.
One is that is probably the"industrial" version with a wide temperature range.
It proved to be unreliable on people, we had to buy a specific "clinical" version which is quite well-behaved but operates at 2 to 5 cm range.
At 2.5 metres, you are looking at buying an infrared camera system with the corresponding software. It won't be cheap either! 
Do a simple back-of-a-beermat calculation;
Let's say a human face (the only bit that is usually uninsulated) is about 15cm wide.
At 2.5 metres, this represents an angle of about 3.5 degrees.
That's the maximum acceptance angle for your proposed device, and you'd be looking for an accuracy of 0.1 degrees Celsius or better.
Try Melexis, but don't hold your breath.