CN-116841025-B - Astronomical optical system with low tolerance sensitivity and large view field main focus

Abstract

The invention discloses a low-tolerance sensitivity large-view-field main focus astronomical optical system which comprises a main mirror, a correction mirror A, a correction mirror B, a correction mirror C, a correction mirror D, a correction mirror E, a correction mirror F and a focal plane, wherein light rays are reflected by the main mirror and sequentially transmitted through the correction mirror A, the correction mirror B, the correction mirror C, the correction mirror D, the correction mirror E and the correction mirror F to reach the focal plane, and the main mirror is a concave aspheric surface reflecting mirror with a secondary hyperboloid or a high-order aspheric surface. The invention simultaneously realizes lower processing and assembling tolerance sensitivity under the condition that the main focus optical system ensures good imaging of a large field of view, optimizes the position and structural parameters of special glass materials and the focal power of optical elements by analyzing the distribution condition of aberration on each optical surface, and realizes the averaging of the aberration contribution of each optical surface, thereby reducing the processing and assembling tolerance sensitivity.

Inventors

• Dong Yunfen
• PING YIDING
• WANG BIN
• LEI CHENGMING
• ZHANG SUI
• JIAO CHANGJUN

Assignees

• 中科院南京天文仪器有限公司

Dates

Publication Date

20260508

Application Date

20230706

Claims (5)

1. 1. A low tolerance sensitivity large view field main focus astronomical optical system is characterized by comprising a main mirror, a correcting mirror A, a correcting mirror B, a correcting mirror C, a correcting mirror D, a correcting mirror E, a correcting mirror F and a focal plane, wherein light rays are reflected by the main mirror and sequentially transmitted through the correcting mirror A, the correcting mirror B, the correcting mirror C, the correcting mirror D, the correcting mirror E and the correcting mirror F to reach the focal plane, the main mirror is a concave aspheric surface reflecting mirror, the shape of the main mirror is a secondary hyperboloid or a high-order aspheric surface, the shape of the surface is determined by the following formula, The primary mirror is a secondary hyperbolic surface or a high-order aspheric surface, and can leave spherical aberration at an off-axis field, and form positive and negative offset with the aberration of a follow-up correction lens group to balance the full-view field aberration; The correcting lens A is a positive meniscus lens, the curvature radius of the concave surface of the correcting lens A is larger than that of the convex surface of the correcting lens A, and the convex surface of the correcting lens A faces the main lens, so that light rays can be converged; the correcting lens B is a negative meniscus lens, the curvature radius of the convex surface is larger than that of the concave surface, the convex surface faces the main mirror, so that the incident light rays can be diffused to the maximum extent; The materials of the correction mirror A and the correction mirror B are positioned on the glass line; The correcting mirror C is a high-dispersion glass lens with the focal power of 0.0003-0.0004 and the F number of 10.5-12.5, a material with the transmittance higher than 99.5% is selected, the focal power can be positive or negative, the correcting mirror C is used for generating large color difference values in different wave bands, and the correcting mirror C and the correcting mirror A and the correcting mirror B are combined to prepare subsequent achromatism, wherein the material of the correcting mirror C is positioned at the left side of a glass line and is positively deviated from the glass; The correcting mirror D is a negative lens and is positioned in the middle position of the correcting lens group, and the refractive index and the dispersion coefficient are positioned in the middle position of the whole glass line; The correcting mirror E is a biconvex thick lens, and is made of low-refractive-index low-dispersion special glass with refractive index smaller than 1.5 and dispersion value smaller than 70, and forms apochromatic combination with the correcting mirror A, the correcting mirror B, the correcting mirror C and the correcting mirror D; the correcting lens F is a biconvex thick lens, is made of low-refractive-index low-dispersion special glass with refractive index smaller than 1.5 and dispersion value smaller than 70, is close to the focal plane, is matched with the correcting lens A, the correcting lens B, the correcting lens C, the correcting lens D and the correcting lens E to be apochromatic, and is also used for flattening and correcting field curvature; And the distance between the two lenses from the correction lens A to the correction lens E is 20-50 mm.
2. 2. The low tolerance sensitivity large field of view primary focus astronomical optical system according to claim 1, wherein the vertex radius of curvature R of the primary mirror and the caliber D satisfy the relation 1.5< R/2D <1.7.
3. 3. The low tolerance sensitivity large field of view primary focus astronomical optical system according to claim 1, wherein the primary mirror material is SIC or glass material.
4. 4. A low tolerance sensitive large field of view primary focus astronomical optical system according to claim 1, characterized in that the ratio of the concave radius of curvature to the convex radius of curvature of the correcting mirror a is R A Concave recess /R A Convex part ≡3, the edge of the positive meniscus lens is thin and thick in the center, for reducing off-axis advanced spherical aberration and increasing the relative aperture of the system without introducing spherical aberration.
5. 5. The low tolerance sensitive large field of view primary focus astronomical optical system according to claim 1, wherein the ratio of the convex radius of curvature to the concave radius of curvature of the correcting mirror B is R B Convex part /R B Concave recess ≡3, the center thin edge of the negative meniscus lens is thick.

Description

Astronomical optical system with low tolerance sensitivity and large view field main focus Technical Field The invention belongs to the field of astronomical instruments, and particularly relates to an astronomical optical system with low tolerance sensitivity and large view field main focus. Background Since the 20 th century, the international astronomical world has increased the exploration force of outer space, and numerous large-sized optical telescopes have been developed accordingly, and related technologies such as large-caliber foundation optical telescopes and space telescopes have been greatly developed. The current internationally mainstream large-caliber catadioptric telescope is mainly divided into three main categories, namely Cassegrain plus correction lens type, schmidt type and main focus type. In terms of the types of Cassegrain plus correction mirrors, SLOAN astronomical telescope, pan-STARRS and Spanish JST telescope are all of the types, a double-reflection carbocoal system is formed by adding correction mirrors to a primary mirror and a secondary mirror, the system focal ratio is between F3 and F5, and the optical system of the correction lens system can be maximally realized by adding correction mirrors to the primary mirror and the secondary mirror in mass production, such as a RiFast type telescope of Italy Officina Stellare company. In the aspect of Schmidt type, a 0.95 m caliber Kepler mixing telescope, a 1.2 m UK Schmidt telescope, a 1.22 m Zwicky TRANSIENT FACILITY telescope, a 1.2 m Chinese Xuyi near-earth celestial body searching telescope and a 0.5 m Chinese Antarctic sky patrol telescope are all of the types. In the aspect of main focus type, the dark energy spectrometer DESI in the United states is composed of a 4-meter telescope main focus, 4 correction mirrors and 2 atmospheric dispersion correction mirrors, 5-degree ultra-large view field can be realized, and a 0.7-meter caliber MASTA large-view field telescope and a 2.5-meter caliber WFT telescope which are researched in China belong to the main focus telescope. The main focus telescope occupies an important position in the new generation of large-field optical telescope currently being researched, which not only shows the future development trend of the large-field optical telescope, but also shows the important position of the main focus telescope in the field. The imaging quality is a main performance index of the optical telescope, and for a main focus imaging system, the imaging quality of the optical system can be directly affected by the design of the optical system, the processing precision of an optical element, the assembly and adjustment precision of the system and the like, so that the astronomical detection precision is limited. In a traditional main focus system, a main mirror is a paraboloid, large-view-field off-axis aberration mainly depends on correction of a subsequent lens group, if details such as material selection, optical structure collocation, focal power homogenization and the like of the subsequent lens group are not optimized in place, a certain element of the main focus optical system can be sensitive to tolerance, and the tolerance of other elements is particularly loose, so that the tolerance sensitivity of the whole system is too large, and adverse effects are brought to subsequent processing and adjustment work. Therefore, the tolerance sensitivity of the large-view-field main focus system is controlled from the optical design stage, and the reasonable distribution of the processing precision and the adjustment precision of the optical element is a key step of telescope design. The main focus optical system with low tolerance sensitivity can enable the imaging performance of the system which is actually assembled and called to be closer to the imaging performance of theoretical design, improve the tolerance capability of the optical system, ensure that the main focus optical system has large field of view, more optical elements and low tolerance sensitivity, simplify the adjustment steps and reduce the assembly and adjustment complexity of the system, and in addition, the telescope system with low tolerance sensitivity can be better suitable for severe environments of outdoor sites, such as windy weather, ground construction vibration and the like, and the telescope optical elements can keep good imaging even if slight imbalance occurs due to various accidental or unexpected situations, thereby improving the detection precision. In a word, the optical system with low tolerance sensitivity has loose tolerance requirement, can better resist image quality degradation caused by errors, reduces manufacturing cost and improves the realizability of the optical system. Disclosure of Invention The invention designs the low-tolerance sensitivity large-view-field main focus astronomical optical system, and the low-tolerance sensitivity of machining and assembly is realized under the condition that