Optimal design of the computational flat diffractive optical system.

A design method of the computational flat diffractive computational flat diffractive optical system is presented to simplify the optical system structure and achieve high image quality. The aberration expression of the flat diffractive optical element (FDOE) is derived, and then computational imaging methods are used to eliminate the influence of off-axis aberration on image quality, so the field of view is expanded. Based on theoretical analysis, the FDOE is designed, and the field of view has been expanded from 2° to 5°. The results show that the detail resolution of the edge field of view is enhanced after restoration, and the modulation transfer function (MTF) of different subareas calculated using the slanted-edge method improved by an average of 0.17. The diffraction efficiency of the FDOE is greater than 95.75%. This method realizes the miniaturization and lightweight of the optical system, and provides new ideas for the integration of optical systems.

Optical design of a monolithic compressed folding imaging lens for infrared/laser dual-band.

In order to realize the miniaturization of the dual-band system, the monolithic compressed folding imaging lens (CFIL) is designed for infrared/laser dual-band in this paper. The relationship among the back focal length, field of view, pupil diameter, and central obscuration of the CFIL are derived. The design method of the dual-band CFIL is given, and the stray light of the CFIL can be suppressed by the double-layer hood structure. According to the design method of the CFIL, the infrared/laser dual-band can be applied by a monolithic optical element. The design results show that the minimum MTF for all fields of view in the infrared band is greater than 0.125 at 42lp/mm, the spot uniformity in the laser band is greater than 90%, and the total system length is only 0.305 times the focal length. After tolerance analysis, the MTF of CFIL is greater than 0.1, and the spot diagram is less than 880µm. The working temperature of the system is -20∼50°C, and the compensation distance is given. After stray light optimization, The point source transmittance (PST) value in the infrared band is reduced by 2 to 4 orders of magnitude, and the PST value in the laser band is reduced by 1 to 5 orders of magnitude. Compared with the traditional coaxial reflective system, the infrared/laser dual-band CFIL has only one lens, and the optical structure is compact. It provides a new idea for the integration and miniaturization of the multi-band system.