LumaSense Technologies M340 - Manual (Page 26)

M340 Manual Appendix B: Calibration Methods 26
Background Influence On Apparent Emissivity
When using a blackbody source at temperatures near ambient and above, common sense
dictates how the blackbody will behave. When using a source below ambient temperatures,
different things happen. Since the background such as the room, wall, and you are warmer than
the blackbody emitter, the energy emitted from the emitter is the sum of the background
reflection and the emitter temperature. When emitter emissivity is less than 1.0, the background
energy times (1-emissivity) reflects to the device under calibration. When the source is set a low
temperatures such as -10 and -20 C, this additional reflection component can become quite
influential. For more information on this subject, contact LumaSense directly.