The Design Of Optical System Of Low-light-level Night Vision With Large Field

A low-light level night vision utilizes image intensifier to process low-light image by e photoelectric conversion method in order to implement night observation, and can be used to detect and strike targets at night. Over the years, military aircrafts are equipped with the low-light night vision device which view field is from 30°to 45°. However, when performing their tasks, the pilot's field of view will be limited by a small view field of conventional low-light level night vision, which probably leads to omission of targets. To solve this problem, this paper studies a low-light level night vision with large field, and designs a nearly continuous wide-field optical system with is more suitable to human eye. The paper mainly studies the following aspects:Firstly, it briefly describes the principle and the development trend of the image intensifier, the core of low-light level night vision, chooses three generations of image intensifier as the subject of design of the core components by the analysis of technical specifications and requirements of actual combat.Secondly, it demonstrates the overall program of the large field of view night vision, uses multi-lens structure and combines the principle of composite image, determines the overall plan and design parameters of low-light level night vision.Finally, according to the technical requirements, it calculates parameters of the objective lens and ocular in the large field of low-light level night vision, and evaluates image quality of design results in optical system.This paper selects five sets seven double Gauss lens as the initial structure of lens, uses double diamond as the composite image structure of field for main objective and secondary objective, selects a long working distance Huygens optical system as the initial structure of eyepiece, designs a large field of low-light level night vision that image quality meets the technical requirements. The results show that by using diffractive elements with aspheric in optical systems, it not only improves image quality and simplifies structure but also lower system weight while reducing the system size.