A short-wave, long-wave infrared dual-band confocal surface large relative aperture optical system

Abstract

The invention provides a large relative aperture optical system which adopts less material, small size and compact structure, and can effectively eliminate the chromatic aberration between the wavelength bands and the wavelength band in the dual-band system. The optical system includes a front fixed mirror group, a diaphragm, an intermediate fixed mirror group, a rear fixed mirror group and a detector which are arranged and connected in sequence from the object side to the focal plane; the front fixed mirror group, the diaphragm, the middle fixed mirror group and the rear fixed mirror group The central axis of the fixed lens group is coaxial; the front fixed lens group has positive refractive power, and includes a first positive lens, a first negative lens and a second negative lens that are coaxially arranged in sequence from the object side to the central axis in the direction of the focal plane. lens; the middle fixed lens group has negative refractive power, including a second positive lens and a third negative lens that are coaxially arranged in sequence from the object side to the central axis of the focal plane direction; the diaphragm is fixed at the third negative lens and the third negative lens. Between the two positive lenses; the rear fixed mirror group is the third positive lens.

Description

technical field [0001] The present invention relates to an optical system design for two bands of short-wave infrared and long-wave infrared, in particular to a common optical path confocal surface using only transmission elements and including two bands of short-wave infrared 0.9 μm-1.7 μm and long-wave infrared 8 μm-12 μm optical system design. Background technique [0002] Like visible light imaging, near-infrared imaging is usually the detection of radiation reflected from targets or backgrounds. However, due to the longer wavelength of the latter, it is less affected by atmospheric scattering, the working distance can be longer, and the latter has better smoke penetration ability, which makes near-infrared imaging have better environmental adaptability; long-wave infrared imaging It is mainly to detect the radiation characteristics of the object itself. It is an ideal band for detecting the infrared characteristics of the target in a specific background. At the same ti...

AI Technical Summary

Problems solved by technology

The transmissive optical system disclosed in the article has an F-number of 1.4 or 1.6 when the focal length is 50 mm, and at least three aspherical surfaces are used, and some designs also use diamond, cesium iodide (CsI), Materials such as cesium bromide (CsBr) that are difficult to process or have unstable physical and chemical properties make the entire optical system lack engineering feasibility; another lens design using a catadioptric structure has an F number of 10000 at a focal length of 50mm. 1.3

Although the lens only uses two pieces of multi-spectral ZnS lenses, each optical reflection surface and transmission surface of the lens are processed on two pieces of ZnS lenses, and the lens also contains Mankin mirror elements, which will lead to strict tolerances of the entire optical system , the processing is more difficult, and the larger central occlusion also reduces the light energy utilization rate of the entire system, which to a large extent offsets the advantages of the small F number of the lens; in addition, this document also announced a three-dimensional Reflective optical design, the focal length of the entire optical system is 50mm, and the F number is 1.9. Although the entire system has no central obstruction and is compact, it still has a larger volume than the transmissive system, and the three reflective surfaces are all Zernike surfaces. It also increases the difficulty of processing and assembling the three-anti system

Images