Infrared Cameras Spectral Range and Derived Temperature

[fog37]

Hello Forum,

I am wondering why infrared cameras can only detect radiation between 1micron to 15micron. This clearly depends on the sensor's material. Based on Wien's law, this corresponds to temperatures from -79C to 89C. Are infrared cameras only detecting within this spectral range because it corresponds to a temperature range (-79 to 89C) which is practical and typical for everyday objects? What if the temperature was higher? A flame is much hotter than 89C. Capturing radiation from this limited spectral range seem a big limitation on which temperatures we can measure.

Thanks!

 

[Mech_Engineer]

Thermal cameras don't just depend on Wien's law, the ones I'm familiar with assume an emissivity for the object (or have you define the emissivity) and then use a calibrated correlation table for total infrared energy wrt temperature. Each pixel provides an intensity (total infrared energy at that pixel, within it's wavelength sensitivity range) and then guesses at the temperature.

More reading on the topic: https://en.wikipedia.org/wiki/Thermographic_camera