RU217680U1 - TWO-CHANNEL MIRROR-LENSING SYSTEM - Google Patents

Abstract

The utility model relates to the field of optoelectronic instrumentation and can be used in multichannel optoelectronic systems designed to detect and recognize objects of observation in the visible and infrared regions of the spectrum.

A two-channel mirror-lens system consists of a main concave aspherical mirror with a central hole located along the beams, a spectrum splitter made in the form of a concave-convex aspherical lens with a dichroic coating on the convex surface, the first channel containing the first positive convex-concave lens, the second positive convex - a concave aspherical lens, a third negative convex-concave lens, a fourth positive convex-concave lens and an infrared radiation receiver, a second channel containing a first concave-convex aspherical lens, a second positive concave-convex lens, a third negative concave-convex aspherical lens , a fourth negative convex-concave lens, a fifth positive concave-convex lens and a radiation receiver, for example, in the visible range of the spectrum. The spectrum splitter is installed in the converging beam after the primary mirror and simultaneously performs the functions of the secondary mirror of the first channel and the first lens of the second channel. Additionally, an optical filter is shown. Due to the design of the spectrum splitter and the lens elements of the first and second channels, a reduction in the length of the optical scheme of the channels is achieved, which makes it possible to improve the weight and size characteristics of the two-channel mirror-lens system. 1 ill., 2 tab.

Description

The utility model relates to the field of optoelectronic instrumentation and can be used in multichannel optoelectronic systems designed to detect and recognize objects of observation in the visible and infrared regions of the spectrum.

A mirror-lens system is known (see patent RU 2089930, IPC G02B 17/08, publ. 09/10/1997), containing the first optical channel, including a Mangin lens, the first refractive surface of which is coated with a dichroic coating, a spectrum divider, and a three-lens compensator and a second optical channel including a Mangin lens, a three-lens afocal attachment, a swivel mirror, a scanning reflector, and a lens. The spectrum splitter is made in the form of a concave-flat lens with a dichroic coating on a flat surface and functions as a counter-reflector of the first channel and the first lens of the afocal attachment of the second channel. The system is designed to operate in two spectral ranges: 0.4…0.9 and 8…14 µm.

The disadvantages of this system are the loss of radiation when passing through the Mangin lens and large overall dimensions.

Also known is a multispectral imaging system with a common aperture (see patent CN 202024818, IPC G02B 27/10, G02B 17/08, G02B 1/10, publ. an optical system and a radiation receiver, and a second channel with an optical system and a learning receiver. The spectrum splitter is made in the form of a concave-convex lens with a dichroic coating on the convex surface and serves as a secondary mirror of the first channel and the first lens of the optical system of the second channel.

In the first channel, the system is designed to operate in the spectral range of 0.4...1 µm, in the second channel - in two infrared ranges: 3...5 and 8...12 µm.

The disadvantage of this system is the large overall dimensions, the reduction of which is ensured by the presence of three rotary mirrors, which complicate the alignment of the optical system.

Also known is a two-channel mirror-lens system presented in the patent for invention RU 2672703, IPC G02B 17/08, G02B 23/04, publ. 11/19/2018 The system consists of a thermal imaging channel containing the first component in the form of a main concave aspherical mirror with a central hole and a secondary convex aspherical mirror, the second component is made in the form of positive convex-concave and concave-convex lenses, a negative concave-convex lens and a positive convex-concave lens, between which an intermediate image is formed, and a radiation receiver, and a television channel located in the central shielding zone of the thermal imaging channel and having a common optical axis with it, containing a positive concave-convex lens with a reflective coating in the central zone of the convex surface , the main concave aspherical mirror and the radiation receiver. In the thermal imaging channel, the focal length of the system is f=304 mm, the aperture ratio is 1:2, the central screening coefficient k _eq =0.3. In the television channel, the focal length is f=112 mm, the relative aperture is 1:4, the central screening coefficient k _eq =0.4.

The disadvantages of this system include a small focal length and a low relative aperture of the television channel.

The closest in technical essence to the claimed system, selected as a prototype, is a dual-band infrared optical system for medium and short wavelengths with a large aperture (see patent CN 102385158, IPC G02B 27/00, G02B 17/02, G02B 1/00 , G02B 1/02, published 03/21/2012). The system contains a main concave aspherical mirror with a central hole, a secondary convex aspherical mirror, an optical filter, a spectrum splitter, a first group of corrective lenses, a first photodetector, a second group of corrective lenses, and a second photodetector. Spectrum divider made in the form of a flat mirror with a dichroic coating, installed at an angle to the optical axis in a converging beam of rays after the secondary mirror and dividing the radiation flux into two channels, reflecting short-wave radiation and passing medium-wave infrared radiation. The first corrective group contains the first and third negative concave-convex lenses, the second biconvex and the fourth positive convex-concave lenses. The second corrective group contains the first and third biconvex lenses, the second negative convex-concave, the fourth biconcave and the fifth positive convex-concave lenses. The spectral range of the first channel is 3...5 µm, the second - 1...3 µm. Focal length of the system in both channels f=440 mm; relative aperture 1:1.46; entrance pupil diameter D=300 mm; coefficient of central shielding k _eq =0.5; angular field of view 2ω=1.6°. The length of the system in the first channel L _I =525.2 mm; in the second channel L _II = 564.1 mm. Germanium and silicon are used as lens materials in the first channel, zinc sulfide, quartz, zinc selenide and silicon are used in the second channel.

The disadvantage of the prototype is the large length of the optical system of the first and second channels, which increases the overall dimensions and weight. In addition, a large central shielding factor reduces the effective aperture ratio.

The task to be solved by the utility model is to improve the weight and size characteristics of a two-channel mirror-lens system by reducing the length of the optical scheme of the first and second channels.

The problem is solved due to the fact that in a two-channel mirror-lens system consisting of a main concave aspherical mirror with a central hole located along the beams, a dichroic coated spectrum splitter installed in a converging beam of rays, the first channel containing the first lens, the second positive lens , the third negative lens, the fourth positive convex-concave lens, and the radiation receiver, the second channel containing the first, second and third lenses, the fourth negative lens, the fifth positive lens and the radiation receiver, according to the utility model, the spectrum splitter is installed after the main mirror, is made in the form a concave-convex aspherical lens with a dichroic coating on the convex surface, and simultaneously performs the functions of a secondary mirror of the first channel and the first lens of the second channel, in the first channel the first lens is made positive convex-concave, the second is convex-concave aspherical, the third is convex-concave, in the second channel, the second lens is made positive concave-convex, the third is negative concave-convex aspherical, the fourth is convex-concave, the fifth is concave-convex.

The figure 1 shows the optical scheme of a two-channel mirror-lens system with a beam path.

A two-channel mirror-lens system consists of a main concave aspherical mirror with a central hole 1 located along the beams, a spectrum splitter 2 installed in a converging beam of rays after the main mirror 1 and made in the form of a concave-convex aspherical lens with a dichroic coating on the convex surface, the first channel I, containing the first positive convex-concave lens 3, the second positive convex-concave aspherical lens 4, the third negative convex-concave lens 5, the fourth positive convex-concave lens 6 and the infrared radiation receiver of the spectrum 7, the second channel II containing the spectrum splitter 2 , which performs the function of the first lens of the second channel II, the second positive concave-convex lens 8, the third negative concave-convex aspherical lens 9, the fourth negative convex-concave lens 10, the fifth positive concave-convex lens 11 and the radiation receiver 12, for example, in the visible range spectrum. In the first channel I, the convex surface of the spectrum splitter 2 functions as a secondary mirror. Additionally, an optical filter 13 is shown.

The entrance pupil of the system coincides with the surface of the main mirror pos.1.

As follows from table 1, the length of the optical circuit of the first channel of the proposed system L _I =274 mm (see Fig. 1), which is less than the prototype by 1.9 times. In the second channel at a focal length f=280.2 mm, the length of the optical circuit L _II =241.7 mm; after scaling up to the focal length of the prototype f=440 mm, the length of the optical scheme L _II is 379.8 mm, which is 1.5 times less compared to the prototype.

Reducing the length of the optical scheme of channels is achieved by choosing the design of the spectrum splitter and lens elements of the first and second channels.

The two-channel mirror-lens system operates as follows. Radiation from an infinitely distant object hits the concave surface of the main mirror 1, is reflected from it and hits the convex surface of the spectrum splitter 2. In the first channel I, the radiation of the mid-infrared range of the spectrum is reflected from the convex surface of the spectrum splitter 2 and is focused in the intermediate image plane, then by lenses 3- 6 of the first channel I is transferred to the plane of the sensitive elements of the radiation detector 7. In the second channel II, the radiation of the visible range of the spectrum passes through the spectrum divider 2, which acts as the first lens of the second channel II, lenses 8-11 and is focused in the plane of the sensitive elements of the radiation detector 12. Lenses 3 -6 in the first channel I and lenses 8-11 in the second channel II provide correction of field aberrations of the optical system.

Thus, the implementation of a two-channel mirror-lens system in accordance with the proposed technical solution makes it possible to improve its weight and size characteristics by reducing the length of the optical scheme of the first and second channels.

Claims (1)

A two-channel mirror-lens system, consisting of a main concave aspherical mirror with a central hole located along the beams, a dichroic coated spectrum splitter installed in a converging beam of rays, the first channel containing the first lens, the second positive lens, the third negative lens, the fourth positive convex a concave lens, and a radiation receiver, the second channel containing the first, second and third lenses, the fourth negative lens, the fifth positive lens and the radiation receiver, characterized in that the spectrum splitter is installed after the main mirror, is made in the form of a concave-convex aspherical lens with a dichroic coating on a convex surface, and simultaneously performs the functions of a secondary mirror of the first channel and the first lens of the second channel, in the first channel the first lens is made positive convex-concave, the second - convex-concave aspherical, the third - convex-concave, in the second channel the second lens is made positive concave -convex, the third - negative concave-convex aspherical, the fourth - convex-concave, the fifth - concave-convex.

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