Design and theoretical analysis of the image-side telecentric zoom system using focus tunable lenses based on Gaussian brackets and lens modules

For now, telecentric system and zoom system have been extensively implemented in machine vision, industrial inspection, etc. However, studies on optical systems with both telecentric and zoom functions are still rare. To improve this situation, we present the design method of the telecentric zoom system with four focus tunable lenses (FTL) and a moving aperture stop (STOP) by applying Gaussian brackets and lens modules. We first improve the Gaussian brackets to achieve the initial parameter solution of the telecentric zoom FTL system, then we introduce a selection method to find the initial structural parameters with sufficient potential for optical design. After that, we use the lens module method to design the initial structure of the optical system, we also expand the combination method of the lens modules which contains an FTL. Finally, the initial structures of a 4X image-side telecentric zoom FTL system are constructed as an example and then optimized using CODEV. As a result, we get an image-side telecentric zoom FTL system with an F/# of 4, a zoom range of 20 mm to 80 mm, an image plane size of 8 mm, and a total length of 218 mm, which performs well in telecentricity control, distortion control, and aberration correction.