RU2338227C2 - Optical system for ir spectral region (versions) - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: optical system contains lens forming true intermediate image, containing first positive lens and positive meniscus concave to image, projection lens, containing first two lenses with common positive focal power, third positive lens and fourth positive meniscus concave to image, and true offset exit pupil. In the first version negative lens with second concave surface is introduced into lens after positive meniscus. And projection lens contains first positive lens with second convex surface, second negative lens with first concave surface and third lens with first convex surface. In the second version negative lens is introduced into lens before positive meniscus with first concave surface, and projection lens is executed as in the first version. In the third version negative lens is introduced into lens after positive meniscus with second concave surface and projection lens contains first negative lens with second concave surface, second positive lens with second convex surface. In the fourth version negative lens is introduced into lens before positive meniscus with first concave surface and projection lens is executed as in the third version.

EFFECT: higher aperture ratio of optical system for IR spectral region with true intermediate image and true offset exit pupil.

4 cl, 4 dwg

Description

The proposed solution relates to optical instrumentation and can be used in devices that record thermal radiation in the middle and far infrared spectral range.

Known optical systems for the infrared region of the spectrum, containing a lens that builds a valid intermediate image, a projection lens and a valid remote exit pupil (RF patent No. 2244949; Proceedings of SPIE, vol. 5783, 2005, p.781, fig. 4; Proceedings of SPIE, vol. 5783, 2005, p. 880, fig. 6).

The presence of a valid remote exit pupil allows it to be combined with a cooled diaphragm of a photodetector (FPU).

The entrance pupil in these optical systems is located near the first lens of the lens, which allows to reduce the diameters and mass of the most dimensional lenses of the optical system.

The disadvantage of such optical systems is their low aperture.

The closest technical solution to the claimed solution is an optical system for the infrared region of the spectrum ("Proceedings of SPIE", vol. 5783, 2005, p.781, fig.4, Narrow Field of View), selected as a prototype, containing sequentially arranged along the rays of the lens, building a valid intermediate image containing the first along the rays of the positive lens and a lens made in the form of a positive meniscus facing concavity to the image, a projection lens containing three positive and one negative lens, along the beam th first two lenses have a common positive optical power, a positive third lens, the fourth lens is formed in the shape of a positive meniscus facing to the image is concave, and the actual imposed on the exit pupil of the optical system.

This optical system operates in the spectral range from 8 to 12 microns.

The disadvantage of this optical system is its low aperture ratio. With a focal length of 60 mm and an angular field of view of 7.5 °, the relative aperture is 1: 2.

The objective of the proposed technical solution is to increase the aperture ratio of the optical system for the infrared region of the spectrum having a valid intermediate image and a valid remote pupil.

This is achieved by the fact that the optical system for the infrared region of the spectrum, containing a lens sequentially arranged along the rays, constructing a real intermediate image, containing the first positive lens along the rays and a lens made in the form of a positive meniscus facing concavity to the image, a projection lens, containing three positive and one negative lens, along the rays the first two lenses have a positive total optical power, the third lens is positive, the fourth lens is made in The shape of the positive meniscus facing the concavity to the image and the actual remote exit pupil of the optical system are characterized in that a negative lens with a second concave surface is inserted into the lens after the positive meniscus, and the projection lens contains the first positive lens with the second convex surface and the second a negative lens with a first concave surface and a third lens with a first convex surface.

In the second embodiment, the optical system for the IR region of the spectrum is characterized in that a negative lens with a first concave surface is inserted into the lens in front of the positive meniscus, and the projection lens contains, along the rays, a first positive lens with a second convex surface, a second negative lens with a first concave surface and a third lens with a first convex surface.

In the third embodiment, the optical system for the IR region of the spectrum is characterized in that a negative lens with a second concave surface is inserted into the lens after a positive meniscus, and the projection lens contains, along the rays, a first negative lens with a second concave surface, a second positive lens with a second convex surface .

In the fourth embodiment, the optical system for the IR region of the spectrum is characterized in that a negative lens with a first concave surface is inserted into the lens in front of the positive meniscus, and the projection lens contains, along the rays, a first negative lens with a second concave surface, a second positive lens with a second convex surface .

The presented illustrations explain the essence of the proposed solution.

Figure 1 shows the optical scheme of the optical system for the infrared region of the spectrum.

Figure 2, 3, 4 shows the optical scheme of the optical system for the infrared region of the spectrum in the second, third and fourth variants of execution, respectively.

The optical system for the infrared region of the spectrum contains a lens A arranged in series along the rays of the beam, building a real intermediate image, a projection lens B and a real remote exit pupil located behind the projection lens. Lens A contains along the rays of the first positive lens 1, the second lens 2, made in the form of a positive meniscus, facing a concavity to the image, and a third negative lens 3 with a second concave surface. Projection lens B contains three positive 4, 6, 7 and one negative 5 lenses. The first two along the rays of the lens 4 and 5 have a positive total optical power, along the rays of the first positive lens 4 has a second convex surface, the second negative lens 5 has a first concave surface, the third positive lens 6 has a first convex surface, the fourth lens 7 is made the shape of a positive meniscus facing concavity to the image.

According to the second embodiment, the lens A contains, along the rays, the first positive lens 1, the second negative lens 2 with the first concave surface and the third lens 3, made in the form of a positive meniscus, facing the concavity to the image.

According to the third embodiment, the projection lens B comprises, along the rays, a first negative lens 4 with a second concave surface and a second positive lens 5 with a second convex surface.

According to the fourth embodiment, the lens A contains, along the rays, the first positive lens 1, the second negative lens 2 with the first concave surface and the third lens 3, made in the form of a positive meniscus facing the concavity to the image, and the projection lens B contains the first negative lens along the rays 4 with a second concave surface and a second positive lens 5 with a second convex surface.

The optical system operates as follows. Lens A constructs a real intermediate image of a distant object, and projection lens B reimages it into the image plane, which coincides with the photosensitive area of the FPU.

The actual pupil of the optical system coincides with the cooled FPU diaphragm (not shown).

In accordance with the proposed solution in the first embodiment, an optical system was obtained for the infrared range from 7.5 to 11 μm. The design parameters of the optical system are shown in table 1.

Table 1 Radii, mm Thickness mm Refractive indices r1 = 276.83 d1 = 22 4,002172 r2 = 415.58 d2 = 63.02 r3 = 92.91 d3 = 17 4,002172 r4 = 95.68 d4 = 20 r5 = 121.29 d5 = 10 2,766696 r6 = 65.075 d6 = 89.58 pr. d6 '= 76.4 r7 = -409.84 d7 = 9 4,002172 r8 = -144.66 d8 = 12 r9 = -88.31 d9 = 8 2,407452 r10 = -137.13 d10 = 1 r11 = 65.635 d11 = 10 4,002172 r12 = 76.97 d12 = 1 r13 = 32.34 d13 = 12 4,002172 r14 = 25

Characteristics of the optical system:

- focal length - 150 mm;

- relative aperture 1: 0.8;

- angular field of view - 3 °;

- the removal of the exit pupil is 25 mm.

The optical system has aberrations for a wavelength of λ = 10.6 μm:

- longitudinal spherical aberration for a point on the axis of not more than 0.030 mm;

- meridional astigmatic segment of not more than 0.009 mm;

- sagittal astigmatic segment of not more than 0.036 mm;

- distortion - not more than 1.2%.

The optical system has chromatic aberration for the spectral range from 7.5 to 11 microns:

- chromatism position - 0,053 mm;

- Chromatism of increase - not more than 0.011 mm.

In accordance with the proposed solution in the second embodiment, an optical system was obtained for the infrared range from 7.5 to 11 μm. The design parameters of the optical system are shown in table 2.

table 2 Radii, mm Thickness mm Refractive indices r1 = 823.09 d1 = 20 4,002172 r2 = -2834.3 d2 = 78.74 r3 = -223.92 d3 = 10 2,766696 r4 = -584.2 d4 = 1 r5 = 112.17 d5 = 14 4,002172 r6 = 126.67 d6 = 114.76 pr. d6 '= 59.5 r7 = -362.3 d7 = 9 4,002172 r8 = -133.19 d8 = 12 r9 = -64.99 d9 = 8 2,407452 r10 = -92.85 d10 = 1 r11 = 89.56 d11 = 10 4,002172 r12 = 129.64 d12 = 1 r13 = 31.84 d13 = 12 4,002172 r14 = 25

Characteristics of the optical system:

- focal length - 150 mm;

- relative aperture 1: 0.8;

- angular field of view - 3 °;

- the removal of the exit pupil is 25 mm.

The optical system has aberrations for a wavelength of λ = 10.6 μm:

- longitudinal spherical aberration for a point on the axis of not more than 0.027 mm;

- meridional astigmatic segment of not more than 0.051 mm;

- sagittal astigmatic segment of not more than 0.023 mm;

- distortion - not more than 1%.

The optical system has chromatic aberration for the spectral range from 7.5 to 11 microns:

- chromatism position - 0,068 mm;

- Chromatism of increase - not more than 0.011 mm.

In accordance with the proposed solution in the third embodiment, an optical system was obtained for the infrared range from 7.5 to 11 μm. The design parameters of the optical system are shown in table 3.

Table 3 Radii, mm Thickness mm Refractive indices r1 = 246.65 d1 = 24 4,002172 r2 = 349.91 d2 = 104.83 r3 = 85.67 d3 = 14 4,002172 r4 = 90.74 d4 = 20 r5 = 149.98 d5 = 8 2,766696 r6 = 60.58 d6 = 60.37 pr. d6 '= 66.8 r7 = 561.76 d7 = 7 2,407452 r8 = 150.33 d8 = 6 r9 = 3285.3 d9 = 10 4,002172 r10 = -236.9 d10 = 7 r11 = 74.74 d11 = 10 4,002172 r12 = 89.47 d12 = 1 r13 = 37.3 d13 = 12 4,002172 r14 = 25

Characteristics of the optical system:

- focal length - 150 mm;

- relative aperture 1: 0.8;

- angular field of view - 3 °;

- the removal of the exit pupil is 25 mm.

The optical system has aberrations for a wavelength of λ = 10.6 μm:

- longitudinal spherical aberration for a point on the axis of not more than 0.021 mm;

- meridional astigmatic segment of not more than 0.105 mm;

- sagittal astigmatic segment of not more than 0.028 mm;

- distortion - not more than 2%.

The optical system has chromatic aberration for the spectral range from 7.5 to 11 microns:

- chromatism of the position - 0.011 mm;

- Chromatism of increase - not more than 0.011 mm.

In accordance with the proposed solution for the fourth embodiment, an optical system was obtained for the infrared range from 7.5 to 11 μm. The design parameters of the optical system are shown in table 4.

Table 4 Radii, mm Thickness mm Refractive indices r1 = 434.44 d1 = 21 4,002172 r2 = 1247.8 d2 = 95.8 r3 = -241.04 d3 = 11 2,766696 r4 = -1820.6 d4 = 1 r5 = 113.49 d5 = 15 4,002172 r6 = 136.83 d6 = 104.2 pr. d6 '= 50 r7 = 530.54 d7 = 6 2,407452 r8 = 150.09 d8 = 8 r9 = -3213.2 d9 = 9 4,002172 r10 = -224.62 d10 = 7 r11 = 88.16 d11 = 10 4,002172 r12 = 132.56 d12 = 1 r13 = 31.69 d13 = 12 4,002172 r14 = 25

Characteristics of the optical system:

- focal length - 150 mm;

- relative aperture 1: 0.8;

- angular field of view - 3 °;

- the removal of the exit pupil is 25 mm.

The optical system has aberrations for a wavelength of λ = 10.6 μm:

- longitudinal spherical aberration for a point on the axis of not more than 0.022 mm;

- meridional astigmatic segment of not more than 0.003 mm;

- sagittal astigmatic segment of not more than 0.009 mm;

- distortion - not more than 1.1%.

The optical system has chromatic aberration for the spectral range from 7.5 to 11 microns:

- position chromatism - 0.062 mm;

- chromatism increase is not more than 0.01 mm

Thus, the technical result of the proposed solution is the creation of an optical system for the infrared region of the spectrum with a valid intermediate image and a valid remote pupil with high aperture, operating in the middle and far infrared region of the spectrum with a relative aperture of at least 1: 0.8.

Claims (4)

1. An optical system for the infrared region of the spectrum, containing a lens sequentially located along the rays, constructing a real intermediate image, containing the first positive lens along the rays and a lens made in the form of a positive meniscus facing the concavity to the image, a projection lens containing three positive and one negative lens, along the rays the first two lenses have a common positive optical power, the third lens is positive, the fourth lens is a positive meniscus facing bent to the image, and the actual remote exit pupil of the optical system, characterized in that a negative lens with a second concave surface is inserted into the lens after the positive meniscus, and the projection lens contains, along the rays, the first positive lens with a second convex surface, the second negative lens with the first concave surface and a third lens with a first convex surface. 2. An optical system for the infrared region of the spectrum, containing a lens sequentially arranged along the rays of the lens, constructing a valid intermediate image, containing the first positive lens along the rays and a lens made in the form of a positive meniscus facing concavity to the image, a projection lens containing three positive and one negative lens, along the rays the first two lenses have a common positive optical power, the third lens is positive, the fourth lens is a positive meniscus facing bent to the image, and the actual remote exit pupil of the optical system, characterized in that a negative lens with a first concave surface is inserted into the lens in front of the positive meniscus, and the projection lens contains, along the rays, a first positive lens with a second convex surface, a second negative lens with a first concave surface and a third lens with a first convex surface. 3. An optical system for the infrared region of the spectrum, containing a lens sequentially located along the rays, constructing a real intermediate image, containing the first positive lens along the rays and a lens made in the form of a positive meniscus facing the concavity to the image, a projection lens containing three positive and one negative lens, along the rays the first two lenses have a common positive optical power, the third lens is positive, the fourth lens is a positive meniscus facing bent to the image, and the actual remote exit pupil of the optical system, characterized in that a negative lens with a second concave surface is inserted into the lens after the positive meniscus, and the projection lens contains, along the rays, the first negative lens with the second concave surface, the second positive lens with the second convex surface. 4. An optical system for the infrared region of the spectrum, containing a lens sequentially located along the rays, constructing a real intermediate image, containing the first positive lens along the rays and a lens made in the form of a positive meniscus facing concavity to the image, a projection lens containing three positive and one negative lens, along the rays the first two lenses have a common positive optical power, the third lens is positive, the fourth lens is a positive meniscus, facing obstruction to the image, and the actual remote exit pupil of the optical system, characterized in that a negative lens with a first concave surface is inserted into the lens in front of the positive meniscus, and the projection lens contains, along the rays, a first negative lens with a second concave surface, a second positive lens with a second convex surface.

Images