Integrating Sphere Unit for Precision Measurement of Absolute Reflectance and Transmittance of Spacecraft Materials in a Vacuum Chamber

Abstract

The unit for high absolute accuracy (1%) measurements in situ of the reflectance (total, specular and diffuse) and regular transmittance is described. The measurements of reflectance and transmittance we performed on the same spot of the sample, permitting, first, to calculate absorptance with a high accuracy and, second, to exclude errors induced by structural inhomogeneities of the sample and treatment causes surface detects, the structural inhomogeneities of the sample being due to radiation beam inhomogeneities in the space environment simulator. The high absolute accuracy does not necessitate the use of reference samples, simplifying considerably the unit design, the experiment preparation and the measurement process and hence, reducing the cost of experiment as a whole. The measuring optical block is based on the integrating sphere connected to the outside systems through fiber bifurcated and trifurcated optic cables equipped with collimating and collecting probes. It has the small dimension and is placed easy in a space simulator.KeywordsStructural InhomogeneityReference ChannelOptical CoefficientSpace SimulatorDetector PortThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.