A design of ultra-high definition dual-lens optical system with long back focal length

Inspired by the human visual system, the dual-lens optical system emulates the binocular stereoscopic vision. It captures two perspectives of the same scene from separate viewpoints, creating a sense of depth and a three-dimensional effect. Currently, research progress has been made in the design of dual-lens optical systems in terms of zooming and baseline variation, but there are still issues such as limited field of view and a narrow range of baseline variation. To overcome these limitations and extend the working distance of the system while ensuring image quality, this paper proposes a design method for an ultra-high definition dual-lens optical system with an extended rear stopping distance. This study first compares three traditional binocular stereoscopic imaging techniques (dual-lens dual-sensor, single-lens single-sensor, dual-lens single-sensor), analyzes the shortcomings of the current dual-lens optical system design, and proposes an improvement plan to increase the rear working distance of the system. Based on retaining some of the imaging advantages of the existing dual-lens single-sensor optical system, this study explores the possibility of achieving a long rear focal length and a compact volume by introducing an inverted telephoto structure. In the design process, the two optical paths are completely identical and mirror-symmetrical. This paper first designs a suitable initial structure for one of the optical paths and evaluates and optimizes the image quality. After the image quality meets the requirements, the dual-lens optical system is combined using multiple configurations in ZEMAX software to determine the final system structure. The focus of this study's design is on the inverted telephoto optical system, which adopts an asymmetric structure composed of positive and negative lens groups. The negative lens group reduces the field of view of the off-axis light to the positive group, achieving a wide-angle effect, while the positive lens group ensures that the image is formed on the designated working image plane, thus achieving a long working distance. This study is conducted on ZEMAX software, aiming to achieve an optical system with a rear working distance greater than 50mmand a focal length between 105-150mm, and analyzes the image quality, including the optical point spread function(PSF), modulation transfer function (MTF), spherical aberration, distortion, etc. The evaluation and analysis results of this study show that the image quality of the optical system is good, but further efforts are still needed to achieve good imaging over a wider field of view.