Reflectometer shoot-out: Comparing the performance and accuracy of hand-held reflectometers

摘要

The reflectivity of mirror surfaces is a critical aspect of telescope performance. This is especially true of large adaptive optics systems and interferometers where twenty or more reflective surfaces may be encountered prior to reaching the final detector. The ability to accurately measure the reflectivity of mirrors in-situ allows not only for the determination of system throughput, but also helps to determine when optical elements need cleaning or recoating. We compare the performance of three commercially available, hand-held reflectometers by measuring calibrated reference surfaces of varying reflectivity and scatter characteristics. The reference surfaces are precisely calibrated for absolute reflectivity against NIST traceable standards using a state-of-the-art laboratory reflectometer. Through analysis of the reflectometer measurements of the precisely calibrated surfaces, we determine the relative ability of each reflectometer to measure reflectivity and differentiate scattered light from specular reflection.