Optical design of a double-sided telecentric zoom system with large field of view

Abstract

Double-sided telecentric zoom system (DTZS), characterized by low distortion and high detection accuracy, holds significant promise for applications in machine vision and medical diagnosis. However, the DTZS faces two main drawbacks: one is the lack of a suitable initial structure, and the other is the insufficient field of view (FOV) in existing optical systems. In this paper, the design of large FOV DTZS is taken as an example, and a design method suitable for large FOV zoom system is presented. In this method, the initial structure of the DTZS can be divided into a front fixed-focus system and a rear zoom system, which can be transformed into a general zoom system for design, and then the system is further optimized using ZEMAX. The optimization results show that the DTZS possesses a magnification range from −0.458 × to −0.11 × and a FOV for detection from 24 mm to 100 mm, which can continuous detection of both small and large objects while meeting the precision requirements for diverse objects. The system exhibits excellent imaging quality which controls the telecentricity of both sides within 0.8°, the distortion is trolled within 0.11 %, and the MTF of each zoom configuration is above 0.34 (at 80 lp/mm) throughout the entire FOV. Additionally, the CAM curve of DTZS is smooth without inflexion, and the tolerance values are loose. The DTZS is characterized by a compact structure, large FOV, low distortion, excellent image quality, making it a promising candidate for applications in fields such as industrial automation detection, machine vision.