Design of a Double-Sided Non-Displacement Telecentric Zoom Optical System Using Two Liquid Lens Groups

A double-sided telecentric zoom optical system can ensure the measurement and detection accuracy for different workpiece sizes and plays a crucial role in industrial detection. The conventional double-sided telecentric mechanical zoom system is faced with the problem of complex structure and difficult focusing. To address these issues, a liquid lens is applied to design a non-displacement double-sided telecentric zoom system in this paper. Here, the design method of the conventional double telecentric zoom system is analyzed first; then, the liquid lenses are substituted for the mechanical motion groups. Finally, a double-sided telecentric zoom system with a detection range of 25~60 mm and a magnification of −0.44×~−0.183× has been designed and optimized by Zemax software. The design results show that in the process of magnification, the root mean square radius of the diffuse spot in the system is smaller than the pixel size during the process of zooming. The modulation transfer function values at the Nyquist frequency of 80 lp/mm are all above 0.4, distortion is controlled within 0.2, and telecentricity is less than 0.5°, indicating that the system has excellent imaging quality, low distortion, and high telecentric and other characteristics, which meet system requirements. The design method proposed in this paper can provide an effective solution for the rapid conversion of displacement zoom systems to non-displacement zoom systems.