In the field of earth-observation, on-board calibration is often necessary to guarantee the radiometric accuracy of spaceinstruments. A typical method is to use large diffusers in front of the instrument, illuminated with a reference source likethe sun. Hence, it is necessary to characterize the scattering properties of the diffuser with excellent accuracy. Giventhe large size and weight of the diffusers to characterize, CSL have developed a bench which uses a robot arm tomanipulate the sample. For the most stringent applications, the typical accuracy of robotic arms is not good enough tomeasure the BSDF with a satisfactory accuracy. A method have been developed which uses laser tracker measurementsof the sample during a calibration phase and compensate for the robot errors. This paper describes the principle of themethod and the results obtained. We also present the model of how the orientation error of the sample affects the BSDFrelative error.
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