Cavity effects in coiled coil IR reference source

Two-wavelength differential thermometry for microscopic extended source

“…In the evaluation of the tungsten source as a calibration standard, we found that the filament temperature actually varies as a function of position, resulting in its radiance variation along position and solid angle. Initially, this appeared contrary to our expectations so we made a significant effort to determine the reasons [7,8]. The initial radiance evaluation over the whole projected coiled coil surface indicated that the structure forms a partially transmissive cavity, increasing the temperature of the inner surface elements.…”