Optical system design of high resolution centering instrument based on switchable lenses

Fixed focal length lens was used by the optical module of the traditional centering instrument. Under the principle of reflection measurement, the measurement range is limited when defocusing imaging the curvature center of the measured surface. In view of the above situation, a high resolution centering instrument was developed by switchable lenses. The measurement principle of center aberration of optical lenses was introduced and the calculation formulas of center aberration was given. The optical system of optical measurement module was designed and optimized. According to image quality evaluation results, it can be concluded that the optical system has high imaging quality and meets the requirements of high-precision using. The measurement range of the instrument is -∞ ~ -2 mm and 2 mm ~ +∞, the measurement resolution is better than 2 μm.