Optical system design of continuous zoom objective lens with multi-conjugate distances

This paper presents an optical system of continuous zoom objective lens with multi-conjugate distances which can clearly image at multiple working distances. We firstly design a continuous zoom objective lens with a standard working distance, then optimize it with multiple conjugate distances. When the working distance changes, adjust the position of the image sensor accordingly to achieve clear imaging. The final designed optical system has a working distance range from 65mm to 130mm which can realize a continuous magnification range from 0.18× to 2.65×. The objective lens system can match a 1/2-inch image sensor, and the image sensor can move 16mm relative to the lens. The design results show that the MTF curves for each magnification and working distance are close to the diffraction limit and the imaging performance is good for each configuration. Compared with the conventional continuous zoom objective lens with a fixed working distance, the working distance range of the continuous zoom objective lens with multi-conjugate distances is wider and the zoom ratio is further expanded, which can better meet the requirements of different application scenarios.