RU209190U1 - MIRROR LENS OF THE SPACE TELESCOPE - Google Patents

Abstract

The utility model relates to optical instrumentation, in particular, to space-based mirror lenses. connected and sequentially installed along the beam, the main concave elliptical mirror with a central hole, the secondary convex hyperbolic mirror, the tertiary concave elliptical mirror and the optical unit containing at least one flat mirror located in the plane of the actual image of the entrance pupil, in contrast to the prototype optical the forces of the secondary, tertiary mirrors and the mirror lens of the space telescope satisfy the conditions:, and the distance between the secondary and tertiary mirrors satisfies the condition:, where is the focal length of the mirror object Thus, the proposed mirror lens of the space telescope has small longitudinal dimensions of 1002 mm, while maintaining high image quality close to the diffraction limit in a large angular field of view 2ω≤2.3°.

Description

The proposed utility model relates to optical instrumentation, in particular, to space-based mirror lenses and can be used in high-resolution electronic systems designed for remote sensing of the Earth in order to study natural resources, control emergency situations and other special purposes.

High-resolution remote sensing systems should provide high information content of the obtained images of the earth's surface: have a high linear resolution on the Earth; ensure high accuracy of determining the coordinates of the object; have the ability to use several narrow spectral channels in parallel with the panchromatic channel for complex multispectral imaging.

An anastigmatic three-mirror telescope lens [1] is known, containing an ellipsoidal primary mirror, a hyperboloidal secondary mirror, an ellipsoidal tertiary mirror and a swivel flat mirror located at an angle of 45° to the optical axis of the lens, designed to deflect beams of rays from the secondary to the tertiary mirror, or to reflect light from a tertiary mirror to the image plane. The disadvantages of this lens are:

- large longitudinal dimension of the lens, determined by the distance between the secondary and tertiary mirrors from the dependence: d ₂ ϕ _equiv =0.25, where d ₂ is the distance between the secondary and tertiary mirrors, ϕ _equiv is the equivalent optical power of the lens;

- insufficient angular field of view 2ω=1.5°, large distortion 3.4% at the edge of the image field.

Also known is the lens of a space telescope [2] for remote sensing of the Earth, containing sequentially installed main concave mirror of an elliptical shape, a second convex mirror of a hyperbolic shape, a third concave mirror of an elliptical shape, an aperture diaphragm installed between the third mirror and the image plane. A concentric lens with a concavity facing the image plane is installed near the aperture diaphragm. There is a plane-parallel sealing plate in front of the image sensors. The disadvantages of the given objective of the space telescope are:

- large longitudinal dimension of the lens, determined by the distance between the secondary and tertiary mirrors from the dependence: d ₂ ϕ=0.2;

- large distortion of 3.88% at the edge of the image field with an angular field of view of 2ω=1.5°.

Of the known lenses, the closest in technical essence to the proposed utility model is a mirror lens of a space telescope [3], containing a main concave elliptical mirror, a secondary convex hyperbolic mirror, a third concave elliptical mirror and two flat rotary mirrors, one of which is located in the plane of the actual image of the entrance pupil. The disadvantages of the above prototype are not sufficiently large angular field of view 2ω=1.7° and a relative aperture of 1:12.2, as well as large longitudinal dimensions d ₂ =1484 mm.

The objective of the utility model is to reduce the dimensions of the mirror lens of a space telescope, while maintaining high image quality close to the diffraction limit in a large angular field of view.

The solution of this problem is achieved by the fact that in the mirror lens of a space telescope containing optically coupled and sequentially installed along the beam, the main concave elliptical mirror with a central hole, the secondary convex hyperbolic mirror, the tertiary concave elliptical mirror and the optical unit containing at least one flat a mirror located in the plane of the actual image of the entrance pupil, in contrast to the prototype, the optical powers ϕ ₂ , ϕ _{3 of} the secondary, tertiary mirrors, respectively, and the optical power ϕ _{about the} mirror lens of the space telescope satisfy the conditions:

, где

- фокусное расстояние зеркального объектива космического телескопа.and the distance d ₂ between the secondary and tertiary mirrors satisfies the condition:

, where

is the focal length of the mirror lens of the space telescope.

The choice of optical powers of the secondary and tertiary mirrors, the distance between them provides an increase in the angular field of view, a relative aperture and a decrease in the focal length of the mirror lens of the space telescope, which in turn led to a decrease in size, while maintaining high image quality close to the diffraction limit in a large angular field vision.

Figure 1 shows a schematic optical diagram of the mirror lens of the space telescope.

Figure 2 presents a graph of the modulation transfer function, which is calculated with a uniform distribution of the spectral efficiency in the spectral region (450...850) nm.

SUBSTANCE: space telescope mirror lens contains optically coupled and sequentially installed along the beam the main 1 concave elliptical mirror with a central hole, the secondary 2 convex hyperbolic mirror, the tertiary 3 concave elliptical mirror and the optical block containing at least one flat mirror 4 located in the plane of the real entrance pupil images. Flat mirror 4, located in the plane of the actual image of the entrance pupil, makes it possible to use it as a wavefront corrector to compensate for errors in the manufacture of mirrors 1-3 and assembly of the mirror lens of a space telescope. The optical unit, containing a flat mirror 4 and supplemented by a flat mirror 5, serves for the optimal layout of the mirror lens of the space telescope and allows you to transfer the image to the most convenient place where you can place bulky image receivers.

The mirror lens of the space telescope has the following design parameters and characteristics given in the table:

;1. focal length

;

2. relative aperture 1:11.5;

3. angular field of view 2ω=2.3°;

4. the value of the modulation transfer coefficient (KPM) at a spatial frequency of 55 mm ^-1 within the entire field of view - not less than 0.35;

5. maximum distortion 1.3%;

6. central shielding 0.33.

The operation of the mirror lens of the space telescope is carried out as follows.

The luminous flux emanating from an infinitely distant object falls on the main 1 concave elliptical mirror with a central hole and is reflected from it. Further, this light flux falls on the secondary 2 mirror, reflected from it, is focused in the plane of the intermediate image. The tertiary 3 mirror projects an intermediate image with magnification β ₃ =-1.95 ^x , which is then projected into the focal plane of the space telescope's mirror lens, in which image receivers are installed, using an optical unit consisting of 4-5 flat mirrors.

Thus, the proposed mirror lens of the space telescope has small longitudinal dimensions of 1002 mm, while maintaining high image quality close to the diffraction limit in a large angular field of view 2ω≤2.3°.

SOURCES OF INFORMATION

1. US 4101195 A (National Aeronautics and Space Administration), 06/18/1977, full document.

2. RU 35446 U1 (JSC LOMO), 01/10/2004, entire document.

3. BY 6715 U (JSC Peleng), 10/30/2010, the entire document is a prototype.

Claims (6)

Mirror lens of a space telescope, containing optically coupled and sequentially installed along the beam, the main concave elliptical mirror with a central hole, the secondary convex hyperbolic mirror, the tertiary concave elliptical mirror and the optical unit containing at least one flat mirror located in the plane of the real image of the input pupil, characterized in that the optical powers ϕ ₂ , ϕ _{3 of} the secondary, tertiary mirrors, respectively, and the optical power ϕ _{about the} mirror lens of the space telescope satisfy the conditions: |ϕ ₂ / ϕ _about | = (33…34); |ϕ ₃ / ϕ _about | = (24.5…25.5); and the distance between the secondary and tertiary mirrors satisfies the condition:

, where

is the focal length of the mirror lens of the space telescope.

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