Search

CN-116661116-B - Common-path medium-wavelength-wave double-color athermal refrigerating infrared refraction and reflection optical system

CN116661116BCN 116661116 BCN116661116 BCN 116661116BCN-116661116-B

Abstract

The invention discloses a medium-wavelength double-color athermalization difference refrigeration type infrared refraction and reflection optical system of a common optical path, belongs to the technical field of infrared optics, and aims to solve the problem that the existing common optical path double-band optical system cannot simultaneously athermalize and achromatize. The invention comprises a main reflector, a secondary reflector, a lens group, a cold diaphragm window and an infrared bicolor detector, all components are coaxially arranged to form an imaging system together, an optical system adopts a structure form with a middle real image, the real image surface is positioned between the secondary reflector and the lens group, the main reflector is adopted to carry out primary imaging, the lens group is added behind the primary image surface to carry out secondary imaging and correct off-axis aberration, and the infrared imaging system can be applied to the fields of infrared imaging equipment matched with a refrigeration bicolor detector, a night vision device, an infrared thermal imager, space infrared target detection and the like, and can be used for detecting and imaging a thermal radiation object under an infrared band.

Inventors

  • LIU GUANGSEN
  • WANG ZHILE
  • ZHANG SHUQING
  • JI LINGYUN
  • HE XIAOBO
  • LIU TIANXIN

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260508
Application Date
20230509

Claims (6)

  1. 1. The medium-wavelength double-color athermalization difference refrigeration type infrared refraction and reflection optical system of the common optical path is characterized by comprising a main reflector (101), a secondary reflector (102), a lens group (103), a cold diaphragm window (104) and an infrared double-color detector (105), wherein all components are coaxially arranged to form an imaging system together, the optical system adopts a structure form with a middle real image, and the real image surface is positioned between the secondary reflector 102 and the lens group (103); the main reflector (101) is provided with a central through hole, and the lens group (103) is arranged in front of the central through hole of the main reflector (101); the aperture diaphragm of the optical system is positioned at a cold light stop window (104), and the cold light stop window (104) is arranged at the light output end of the lens group (103); After being reflected by the main mirror 101 and the secondary mirror 102, target light from near infinity forms an intermediate real image before reaching the lens group (103), is refracted by the lens group (103) and passes through the cold light stop window (104), finally, a scene is imaged at the infrared bicolor detector (105) to realize dual-band common-path imaging, wherein the main secondary mirror images an infinite object once, and the lens group (103) images a primary image surface twice so as to adjust the position of an exit pupil, the position of the cold light stop window (104) is the system exit pupil, and the cold light stop efficiency is 100%; the optical system satisfies the following conditions to achieve athermalization and achromatism: In the middle of For the incident height of the lens group, The incidence height in the form of the ith lens fraction in the thin lens group, i.e., normalized incidence height; i=1, 2,..k, k is the number of lenses in the lens group; -coefficient of thermal expansion of barrel material of the lens group; -barrel length of the lens group; Is the optical power of the lens group, An optical power of the i-th lens; Is the color difference coefficient of the lens group, A chromatic aberration system for the ith lens; is the coefficient of thermal difference of the lens group, A thermal differential system for the ith lens; The lens group (103) is coaxially provided with k=5 lenses in the lens cone according to the light propagation direction, wherein the 1 st lens (111) is made of silicon and has positive focal power, the 2 nd lens (112) is made of infrared glass AMTIR1 and has positive focal power, the 3 rd lens (113) is made of germanium and has negative focal power, the 4 th lens (114) is made of silicon and has positive focal power, the 5 th lens (115) is made of zinc selenide and has negative focal power, and the lens cone is made of titanium alloy; If the focal power of the lens group is used The power ranges of the five lenses are in turn: , , , , ; Under the condition of normalizing by focal length, the distance from the main reflector (101) to the secondary reflector (102) is-0.25 to-0.4, the total length of the optical system is 0.3-0.5, the rear surfaces of the 4 th lens 114 in the main reflector (101), the secondary reflector (102) and the lens group are aspheric, and the surfaces of other optical elements are spherical or plane.
  2. 2. The medium-wavelength dual-color athermal refrigeration type infrared refractive and reflective optical system of the common optical path according to claim 1, wherein R1 and R2 respectively correspond to the vertex curvature radiuses of the main reflector (101) and the secondary reflector (102), the value range of R1 is-300 to-500 mm, and the value range of R2 is-80 to-150 mm.
  3. 3. The medium wavelength dual-color athermal refrigeration type infrared refractive optical system of a common optical path according to claim 1, wherein the infrared dual-color detector (105) has a specification of 256×256 pixels and a single pixel size of 30 μm.
  4. 4. The common-path medium-wavelength dual-color athermal refrigeration type infrared refractive and reflective optical system according to claim 1, wherein the distance between the cold diaphragm window (104) and the infrared dual-color detector (105) is 15-25 mm.
  5. 5. The medium-wavelength bicolor athermal differential refrigeration type infrared refractive and reflective optical system of a common optical path according to claim 1, wherein an optical filter or a light splitting component is additionally arranged between the secondary reflector (102) and the lens group (103).
  6. 6. The medium wavelength bicolor athermal refrigeration type infrared refractive and reflective optical system of a common optical path according to claim 1, wherein a light shielding cover is respectively arranged in front of the main reflector (101), at the position of the secondary reflector (102), at the position of the primary focal plane and at the front-back interval of the lens group (103), and a light shielding ring is arranged in front of the main reflector (101).

Description

Common-path medium-wavelength-wave double-color athermal refrigerating infrared refraction and reflection optical system Technical Field The invention relates to the technical field of infrared optics, in particular to a refrigeration type infrared refraction and reflection type optical system. The technology can be applied to the fields of infrared imaging equipment, night vision devices, infrared thermal imagers, space infrared target detection and the like matched with a dual-color refrigeration type detector, can be used for detecting and imaging a thermal radiation object in an infrared band, can keep passive athermalization in a wide temperature range, and has wide application value. Background With the continuous development of modern technology, infrared imaging devices are increasingly popular in the fields of military, security, medical treatment and the like. Because the principle of an infrared optical system is to detect the temperature and emissivity difference between a target and a background, the characteristic difference appears in different wave bands due to different temperatures of the target and the background, and double-color infrared imaging is always a hot spot for research of various countries. In recent years, various companies at home and abroad have developed the condition of developing a dual-color refrigeration type infrared optical system of a common optical path by simultaneously responding to the refrigeration type detector of the medium wavelength radiation. In addition, the thermal effect of temperature on an optical system is largely divided into two effects, namely, the change of refractive index with temperature and the thermal expansion effect of the dimensional thickness of an optical element or a mechanical structure with temperature. Either the refractive index change or the dimensional thickness change can lead to the imaging quality change of the optical system, and the change form is mainly image plane defocus. The correction of the defocus caused by temperature is called optical athermalization, also called athermalization design, and among various athermalization techniques, an optical passive athermalization compensation technique has a simple structure, a small volume, and a light weight, and is widely used. At present, an optical system with the characteristics of athermalization and infrared dual-band imaging is mainly a refractive type optical lens and an optical system with the dual-band common-caliber large target surface, such as an optical athermalization infrared lens and an optical system with the dual-band common-caliber large target surface described by CN112629669B, and adopts a special surface type of a diffraction surface, so that the processing difficulty and the cost are high, and meanwhile, the total length of the system is long. Although the infrared dual-band wide-angle athermal confocal plane optical system described in the application number CN 113866937A does not adopt a diffraction plane, the system is not compact enough and is not suitable for light and small infrared system application scenes. Compared with refraction, the refraction-reflection type optical system has small volume, the total length of the system can be within 50% of the focal length, and the refraction-reflection type refrigeration type infrared optical system is a common structure in an airborne and spaceflight load scene, generally uses two reflectors to image a target once, and uses a lens group to image a primary image surface twice so as to realize the matching of a cold diaphragm and an exit pupil. The simultaneous achromatism and athermalization are always difficulties in developing an optical system with such a structure, for example, the invention described in CN103207452A only realizes the imaging of a dual-band common-path confocal plane, and the athermalization is not realized on the basis. Still another solution is to add a beam splitter between the reflective and refractive elements to separate the optical paths of the two bands to correct for chromatic and thermal differences, respectively, such as in the visible/infrared bicolor common aperture optical system design and implementation (doi: 10.3788/gzxb 20215005.0511002). Although the optical system can achieve better imaging effect, the optical path is complex as a whole, and the light miniaturization and cost control of the optical system are also not facilitated. Disclosure of Invention Aiming at the problem that the existing common-path dual-band optical system cannot simultaneously eliminate thermochromatic and achromatic colors, the invention provides a medium-wavelength-wave double-color thermochromatic refrigeration type infrared refraction and reflection optical system of a common optical path. The invention discloses a medium-wavelength double-color athermal refrigeration type infrared refraction and reflection optical system of a common optical path, which comprises a main reflector 101, a