RU35446U1 - Space telescope lens - Google Patents

Description

IPC: 7 G02B 17/06, 23/06

SPACE TELESCOPE LENS

The proposed utility model relates to the field of optical instrumentation, in particular, mirror and mirror lenses of space telescopes and can be used to improve their technical characteristics, namely to obtain small dimensions, large angular fields, high linear resolution on the ground, etc.

Similar mirror-lens telescope lenses are known, containing the main concave and secondary convex mirrors of an aspherical shape and an optoelectronic receiver (OEP).

The disadvantages of such mirror lenses are the large overall dimensions (length of the system), the complexity of the field aberration corrector, and the limited ability to implement spectral intervals 1.

The closest technical solution to the proposed utility model is the anastigmatic three-mirror telescope lens

The lens adopted for the prototype contains three sequentially mounted mirrors: the first concave mirror of elliptical shape, the second convex mirror of hyperbolic shape and the third concave mirror of elliptical shape. Between the third mirror and the plane

image installed aperture diaphragm mated to the surface of the first mirror. In the focal plane, there are OEPs.

The lens has high image quality over the entire image field, but when installing the protective glasses necessary to ensure the operation of the OEDs, an increase in chromaticity appears, which reduces the image quality across the field.

So, for example, a three-mirror lens without protective glasses with the following parameters:

focal length f - 12000 mm

entrance pupil diameter - 1000 mm

angular field

provides a contrast at a frequency of 56 g / mm in the center of the field - 0.32, and at the edge of 0.30 / 0.31.

When installing protective glasses, the contrast at the edge of the field decreases to 0.02.

The main task, which the utility model is aimed at, is to improve the image quality across the field.

To solve this problem, we propose a lens that,

like the prototype, it contains three consecutively installed main concave mirror of elliptical shape, a second convex mirror of hyperbolic shape, and a third concave mirror of elliptical shape.

2 aperture diaphragm mounted between the third mirror and

image plane and optoelectronic image receivers with

safety glasses.

In contrast to the prototype, a plane-parallel sealing plate installed in front of the optoelectronic receivers and a concentric lens with a concavity facing the image plane mounted near the aperture diaphragm are additionally introduced into the lens, while the optical power of the concentric lens (fl) satisfies the ratio:

Fl (0.15-0.3 5) fob,

where phob is the optical power of the entire lens.

The essence of the proposed lens lies in the fact that a plane-parallel sealing plate is installed in front of the plane of the optoelectronic receivers. The arising chromatism of the increase due to its installation is compensated by an additional concentric lens, turned concave to the image plane and installed near the aperture diaphragm. In this case, the optical power of the lens fd satisfies the ratio:

Fl (0.15 - 0.35) phob., Where phob is the optical power of the entire lens.

The choice of parameters with the ratio described above allowed us to obtain the RMS wavefront strain RMS of less than 0.05X over the entire field, and the contrast value of 56 l / mm in the center

3

Thus, when installing plane-parallel

sealing plate contrast at the edge of the field is reduced to 0.02. The decrease is mainly provided by the increase chromatism introduced by the plane-parallel sealing plate.

The essence of the proposed utility model is illustrated in the drawing, where FIG. 1 is an optical diagram of a lens with two spectral channels and an Appendix.

The lens of the space telescope consists of a main concave mirror 1 of an elliptical shape, a second convex mirror 2 of a hyperbolic shape, a third concave mirror 3 of an elliptical shape and an aperture diaphragm 4, near which a correction, concentric lens 5 is mounted. The image plane 6 of the lens coincides with the surface of the photosensitive zone (PSF) ) of the optoelectronic receiver 7, in front of which there is a plane-flat sealing plate 8.

To dilute the spectral channels, additional flat mirrors 9 are used.

A concentric lens 5, appeals concavity to the image plane, and its optical power fl satisfies the ratio:

Fl (0.15 0.35) phob., Where phob is the optical power of the entire lens.

The lens of the space telescope is as follows.

 . "A parallel beam of light hits the first mirror 1, is reflected

from it and from the second mirror 2 and focuses in the plane of the intermediate image near the top of the first mirror 1. The path of the rays for one of the points of the field (A) is shown in Fig.2. The intermediate image by the mirror 3 is projected in the plane of the OEP 7. For point A, the image is point A. Aperture diaphragm 4 is the exit pupil of the lens, conjugated with the entrance pupil of the lens — the surface of mirror 1. Near the aperture diaphragm 4, a correcting lens close to concentricity is installed 5. The optical power of the concentric lens is 5 fd (0.15 0.35) phobic, t. e. lens 5 is 3-6 times more important than the focal length of the lens, so the light beam passing through it slightly deviates, i.e. a concentric lens 5 performs the functions of a corrector for aberrations introduced by a plane-parallel sealing plate 8.

The light is focused after passing through a plane-parallel sealing plate 8 on the EIA, combined with the image plane 6.

Attached is a lens calculation with the following parameters:

focal length - 17600 mm, entrance pupil diameter - 1500 mm, angular field Before OEP 7 there is a plane-parallel sealing plate 6 with a thickness of 8 mm.

5

RI 327.3

R2 321.4 and an axial thickness of 8 mm.

Correction concentric lens has an optical power equal to 0.274 fl.

Received:

Polychromatic mean square deformation of the wavefront - RMS for the spectral range of 0.5-0.8 microns for the axial point of 0.02X, in the field of less than 0.05 X.

The contrast value of the modulation transfer function (FPM) at the set frequency of 56 l / mm is: for axial points - 0.34 / 0.34 in the field no less than - the edge is 0.30 / 0.30.

For three mirror circuits of the prototype without a plane-parallel sealing plate, the RMS value is:

for axial point RMS 0.04

over the RMS field 6.04 ..

When installing a sealing plane-parallel plate 6 without a corrective concentric lens 5 has an RMS for the axial point of 0.04,

RMS for the extreme point of the field is 0.30, and the contrast is 56 l / mm 008 / 0.264.

Thus, the introduction of a corrective concentric lens compensates for the aberrations introduced by the sealing

"

The advantages of the proposed lens are high

image quality in the presence of a sealing EED plate.

SOURCES OF INFORMATION

1 .N.N.Mikhelson Optics of astronomical telescopes and methods for its calculation, Physics and mathematics, 1995, pp. 328-331.

2. US patent; No. 4101195, IPC:} 02B 17/06, 23/06, 1977 prototype.

Lens System with F 17600 CONSTRUCTIVE N Rayamusy Axial Pow. curvature dist. Non-spherical 1Surface of rotation of the 2nd 2Surface of rotation of 2-ro 3Surface of rotation of the 2nd SUBJECT Delete, size Y IMAGE: Close, size Y DIIFR. S ND About SD

Relative values of the subject: Relative vignetting upper: Relative vignetting | lower order: ECREIN: -2nd

Lens System with F 17600

Paraxial Characteristics

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Claims (1)

The lens of the space telescope for remote sensing of the Earth, containing successively mounted main concave mirror of elliptical shape, a second convex mirror of hyperbolic shape, a third concave mirror of elliptical shape, an aperture diaphragm mounted between the third mirror and the image plane, and optoelectronic image receivers with protective glasses, characterized the fact that a plane-parallel sealing plate installed in front of the optoelectron is additionally introduced into the lens bubbled receivers, and concentric with the concave lens facing the image plane mounted near the aperture, wherein the optical power of the concentric lens (φ _L) satisfies the relation φ _l = (0.15-0.35) φ _about , where φ _r is the optical power of the entire lens.