Abstract: The absolute measurement device of high-precision bidirectional reflectance distribution function (BRDF) can be used to measure the BRDF of the diffuse reflectance reference body such as the calibration diffuse reflector on the satellite. The uncertainty of the rotation angle is one of the main uncertainties of the entire device. By calibrating the geometric position of each component, the angle of the measurement device can be better measured, which can effectively reduce the uncertainty of the absolute measurement of BRDF. In this work, a geometric position calibration method of each component for the absolute measurement device based on its characteristics is developed, where the tandem six-axis robot is used as the measuring tool and the light beam emitted from the integrating sphere light source fixed on the hollow index plate is used as an indicator. The mirror reflection experiment shows that the accuracy of the rotation angle is better than 0.05 ◦ , which meets the application requirements. It is shown that the calibration method not only has high measurement accuracy, but also greatly simplifies the assembly and adjustment process, and realizes non-contact calibration, which provides a reference for the calibration of similar devices.

Key words: geometric optics, uncertainty of rotation angle, six-axis robot, bidirectional re?ectance distribution function, calibration