· Objects may absorb and/or emit radiation.
· All objects above absolute Zero degree (0 F) send out radiation.
· Electromagnetic radiation in rage of 0.0005 mm to 0.0015 mm wave length is known infrared
· It is defined as "thermal (energy) radiation" used for temperature measurement.
· It transfer through vacuum and space at a speed of light.
· object/body material and surface will effect absorbing and emitting of thermal radiation
· thermal equilibrium exists when the absorbed energy is equal to the radiated energy, This is defined in "Kirchoff's Law".
· "An object which is totally non-reflective and completely opaque will absorb all the radiated energy received incident on his surface. This type of body is a perfect absorber and will be therefore a perfect emitter of infrared radiation; referred to us a blackbody object." (quote from James Taylor/Land Instr. Foundation Level Infrared Training"
· The blackbody is used for reference and calibration of infrared cameras
· It is of very high importance that the object material and it's surface is known to achieve high accurate measurements.