US 11,906,718 B2
Wide-aperture spherical primary mirror off-axis afocal optical system
Xinhua Chen, Suzhou (CN); Yueping Lu, Suzhou (CN); Zhicheng Zhao, Suzhou (CN); Qiao Pan, Suzhou (CN); and Weimin Shen, Suzhou (CN)
Assigned to SOOCHOW UNIVERSITY, Suzhou (CN)
Appl. No. 17/908,113
Filed by SOOCHOW UNIVERSITY, Suzhou (CN)
PCT Filed Mar. 18, 2022, PCT No. PCT/CN2022/081568
§ 371(c)(1), (2) Date Aug. 30, 2022,
PCT Pub. No. WO2023/077712, PCT Pub. Date May 11, 2023.
Claims priority of application No. 202111301414.4 (CN), filed on Nov. 4, 2021.
Prior Publication US 2023/0280571 A1, Sep. 7, 2023
Int. Cl. G02B 17/08 (2006.01); G02B 13/18 (2006.01); G02B 27/00 (2006.01)
CPC G02B 17/08 (2013.01) [G02B 13/18 (2013.01); G02B 27/0025 (2013.01); G02B 17/0812 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A wide-aperture spherical primary mirror off-axis afocal optical system comprising:
a primary mirror and a secondary mirror, the primary mirror being a spherical reflector, the secondary mirror being a higher-order aspherical reflector, the primary mirror and the secondary mirror forming an off-axis two-mirror system to compress a beam aperture; and
an aberration compensation mirror group, the aberration compensation mirror group being a coaxial reflective system that is used off-axis, the aberration compensation mirror group having focal power to produce compensation aberrations;
wherein an incident beam passes through and is reflected by the primary mirror and the secondary mirror sequentially and enters the aberration compensation mirror group thereafter,
wherein the aberration compensation mirror group includes a first lens, a second lens and a third lens that are sequentially arranged, a distance from a front surface of the first lens to a rear surface of the third lens is T, the focal length of the aberration compensation mirror group is f2 and they satisfy a relational expression of:
0.7≤f2/T≤1.2;
wherein a focal length of the first lens is f21, a curvature radius of a front surface of the first lens is R3, a curvature radius at a center of a rear surface of the first lens is R4, an on-axis thickness of the first lens is d3, a distance from a front surface of the first lens to a rear surface of the third lens is T, and they satisfy relational expressions of:
−1.85custom characterf21/f2custom character−1.75
1.13custom character(R3+R4)/(R3−R4)custom character1.45
0.09custom characterd3/Tcustom character0.11;
wherein a focal length of the second lens is f22, a curvature radius of the front surface of the second lens is R5, a curvature radius of a rear surface of the second lens is R6, an on-axis thickness of the second lens is d5, a distance from a front surface of the first lens to a rear surface of the third lens is T, and they satisfy relational expressions of:
−3.2custom characterf22/f2custom character−1.15
−1custom character(R5+R6)/(R5−R6)custom character0.3
0.072custom characterd5/Tcustom character0.074;
wherein a focal length of the third lens is f23, a curvature radius of a front surface of the third lens is R7, a curvature radius of a rear surface of the third lens is R8, an on-axis thickness of the third lens is d7, a distance from a front surface of the first lens to a rear surface of the third lens is T, and they satisfy relational expressions of:
1.57≤f23/f2≤1.63
0.41≤(R7+R8)/(R7−R8)≤0.90
0.13≤d7/T≤0.18.