Method for calibrating an optical arrangement

A method for calibrating an optical arrangement in respect to a global coordinate system, the optical arrangement including a carrier unit made of a rigid material, an optical acquiring unit and a light emitting unit both releasably connected to the carrier unit, said method comprising the steps of:

• defining a reference coordinate system (xyz_ref) different from the global coordinate system;
• calibrating an optical acquiring unit or a light emitting unit in respect to the reference coordinate system prior to its intended use and separately from the rest of the optical arrangement by acquiring appropriate calibration data;
• connecting the calibrated optical acquiring unit or light emitting unit to the carrier unit (11);
• performing only once for a given global coordinate system and a given reference coordinate system a conventional calibration of the entire optical arrangement and thereby determining values of a conversion matrix for converting the calibration data acquired in respect to the reference coordinate system into corresponding calibration data in respect to the global coordinate system;
• and
• thereafter, for all further calibrated optical acquiring units and/or light emitting units connected to the carrier unit, making use of the optical acquiring units and/or light emitting units as part of the optical arrangement by considering the calibration data acquired for the optical arrangement or the respective values of the conversion matrix when generating control signals for the units and/or when processing sensor signals received from the units during the intended use of the optical arrangement.