A fast calibration method of optical microscopes

High precision calibration is a key procedure to ensure image measurement system has accuracy measurement results. In the micro-domain applications, such as IC packaging, optical microscopes form a critical component. Although many calibration techniques exist for macroscopic camera-lens system, there is a dearth of literature on optical microscope calibration. Optical microscope calibration has unique characteristics that are quite different from normal camera calibration, including (1) unique calibration parameters; (2) calibration patterns that must be parallel to the image plane, and (3) restriction to single-plane calibration. In this paper, a fast calibration method based on linear relations between the digital image coordinate system and the calibration sample coordinate system is proposed for optical microscopes. We select 2-D dot array calibration plate which where etched on a glass plate as calibration sample. Experiments have been performed and calibration errors have been analyzed.