BRDF and point source transmittance (PST) measurements: review

In modern sensors, including space surveillance, remote sensing, space telescope, high performance interferometry, and laser systems, optical surfaces with rough finish may scatter light in-field. Additionally, in the optical systems for the microelectronic silicon wafer fabrication and inspection, the gate oxide breakdown voltage decreases with the increase in the component roughness. We review principles, approaches, and procedures of performing the BRDF (bidirectional reflectance distribution function) / PST (point source transmittance) measurements, calibration, and the size of detector aperture’s field-of-view. Two measurement calibration approaches are discussed: using a reference, which could be considered a relative method, and straight-through method that obtains an absolute measurement.