Freeform surface optical telescope imaging system

Patent metadata

Field	Value
Publication number	US-11635611-B2
Application number	US-202016999228-A
Country	US
Kind code	B2
Filing date	Aug 21, 2020
Priority date	Jan 15, 2020
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

A freeform surface optical telescope imaging system is provided. The freeform surface optical telescope imaging system comprises a primary mirror, a secondary mirror, a compensating mirror, and a spherical mirror. The primary mirror, the secondary mirror, the compensating mirror, and the spherical mirror are spaced from each other. A surface shape of each of the primary mirror and the secondary mirror is a quadric surface. The primary mirror is used as an aperture stop. A surface shape of the compensating mirror is a freeform surface. A surface shape of the spherical mirror is a spherical surface. A light emitted from a light source would be reflected by the primary mirror, the secondary mirror, the compensating mirror, and the spherical mirror to form an image on an image plane.

First claim

What is claimed is:

1. A freeform surface optical telescope imaging system, comprising:
a primary mirror, a secondary mirror, a compensating mirror and a spherical mirror spaced away from each other, wherein a surface shape of each of the primary mirror and the secondary mirror is a quadric surface, the primary mirror is an aperture stop, a surface shape of the compensating mirror is a freeform surface, a surface shape of the spherical mirror is a spherical surface, a light emitted from a light source is reflected by the primary mirror, the secondary mirror, the compensating mirror, and the spherical mirror to form an image on a image plane, and an F-number of view of the freeform surface optical telescope imaging system is about 9.88.

2. The freeform surface optical telescope imaging system of claim 1 , wherein a first three-dimensional rectangular coordinates system (X,Y,Z) is defined by a location of the primary mirror, a vertex of the primary mirror is an origin of the three-dimensional rectangular coordinates system (X,Y,Z), a reflective surface of the compensating mirror is an xy polynomial freeform surface; and an xy polynomial equation is

z
⁡
(

x
,
y

)

=

c
⁡
(

x
2

+

y
2

)

1
+

1
-

(

1
+
k

)

⁢

c
2

(

x
2

+

y
2

)

+

∑

i
=
1

N

A
i

⁢

x
m

⁢

y
n

,

wherein z represents surface sag, c represents surface curvature, k represents conic constant, and Ai represents an ith term coefficient.

3. The freeform surface optical telescope imaging system of claim 2 , wherein the reflective surface of compensating mirror is a fourth-order polynomial freeform surface of xy without odd items of x; and an equation of the fourth-order polynomial freeform surface of xy is:

z
⁡
(

x
,
y

)

=

c
⁡
(

x
2

+

y
2

)

1
+

1
-

(

1
+
k

)

⁢

c
2

(

x
2

+

y
2

)

+

A
2

⁢
y

+

A
3

⁢

x
2

+

A
5

⁢

y
2

+

A
7

⁢

x
2

⁢
y

+

A
9

⁢

y

Assignees

• Univ Tsinghua
• Hon Hai Prec Ind Co Ltd

Inventors

• Zhu Jun
• Tang rui-rui
• Wu Wei-Chen
• Jin Guo-Fan
• Fan Shou-Shan

Classifications

• G02B23/02 Primary

  involving prisms or mirrors (G02B23/14 takes precedence) · CPC title

• G02B5/10

  with curved faces · CPC title

• G02B17/0663 Primary

  off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements · CPC title

• G02B23/16

  Housings; Caps; Mountings; Supports, e.g. with counterweight · CPC title

• G02B17/0652 Primary

  on-axis systems with at least one of the mirrors having a central aperture · CPC title