Abstract: A high SNR in-situ measurement of sample radiance in a low-temperature ambient environment is used to accurately characterize sample emissivity for transmissive, low-emissivity samples. A low-e mirror is positioned behind the sample such that the sample and low-e mirror overfill the field-of-view (FOV) of the radiometer. The sample is heated via thermal conduction in an open environment. Thermal conduction heats the sample without raising the background radiance appreciably. The low-e mirror presents both a low emission background against which to measure the sample radiance and reflects radiance from the back of the sample approximately doubling the measured signal. The low-e mirror exhibits a reflectance of at least 90% and preferably greater than 98% and an emissivity of at most 7.5% and preferably less than 2% over the spectral and temperature ranges at which the sample emissivity is characterized.

Abstract: A high SNR in-situ measurement of sample radiance in a low-temperature ambient environment is used to accurately characterize sample emissivity for transmissive, low-emissivity samples. A low-e mirror is positioned behind the sample such that the sample and low-e mirror overfill the field-of-view (FOV) of the radiometer. The sample is heated via thermal conduction in an open environment. Thermal conduction heats the sample without raising the background radiance appreciably. The low-e mirror presents both a low emission background against which to measure the sample radiance and reflects radiance from the back of the sample approximately doubling the measured signal. The low-e mirror exhibits a reflectance of at least 90% and preferably greater than 98% and an emissivity of at most 7.5% and preferably less than 2% over the spectral and temperature ranges at which the sample emissivity is characterized.