Middle infrared imaging optical system

Abstract

The invention discloses a middle infrared imaging optical system. The system comprises a front group of lenses, a rear group of lenses and a detector which are positioned on the same optical axis OO', wherein a target forms a primary real image in front of the rear group of lenses through the front group of lenses; the primary real image forms a secondary image on a focal plane through the rear group of lenses; the focal length of each of the front group of lenses is 50mm and the total focal length is 200mm; the magnification ratio of the rear group of lenses is 4; the image surface is increased by about 16 units every time when primary image distance is decreased by 1 unit; and the detector is a refrigerating detector. The system is small and exquisite and compact and can achieve good image quality; and the defocusing caused by temperature variation is compensated by controlling the position of the rear group, the system can work normally within a wide temperature range without refocusing.

Description

technical field [0001] The invention relates to an imaging optical system, in particular to a mid-infrared imaging optical system. Background technique [0002] Broadly speaking, electromagnetic radiation with wavelengths from 0.9 microns to 1000 microns can be called infrared radiation. The atmosphere has different infrared radiation transmittance for different bands. Generally speaking, there are two bands with higher transmittance for infrared radiation. One is 3 microns to 5 microns, which is called the mid-infrared band; the other is 8 microns. To 12 microns, it is called thermal infrared band. [0003] Like visible radiation, infrared radiation is an electromagnetic wave, but with a longer wavelength. Infrared radiation also obeys the laws of reflection and refraction, so it can also be imaged by an optical system like visible light. [0004] There are also many obvious differences between infrared imaging and visible light imaging: first of all, in terms of target ...

AI Technical Summary

Problems solved by technology

[0008] The object of the present invention is to provide a kind of mid-infrared imaging optical system, and its whole optical system is small and exquisite compact, and image quality is good, and transfer function is greater than 0.6 when 16lp / mm, and distortion of field of view is less than 5%; The technical problem of difficult adjustment of the back focus of the optical system of the sensor, and the defocus caused by temperature changes can be compensated by controlling the position of the back group, so that the system can work normally in a wide temperature range without refocusing

Images