Off-axial three-mirror optical system with freeform surfaces

Patent metadata

Field	Value
Publication number	US-9268123-B2
Application number	US-201414571952-A
Country	US
Kind code	B2
Filing date	Dec 16, 2014
Priority date	Mar 5, 2014
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

An off-axial three-mirror optical system with freeform surfaces includes a primary mirror, a secondary mirror, a tertiary mirror, and a detector. The primary mirror is located on an incident light path. The secondary mirror is located on a primary mirror reflecting light path. The tertiary mirror is located on a secondary mirror reflecting light path. The detector is located on a tertiary mirror reflecting light path. Each of the primary mirror, the secondary mirror, and the tertiary mirror is an xy polynomial freeform surface up to the fifth order.

First claim

What is claimed is:

1. An off-axial three-mirror optical system with freeform surfaces comprising:
a primary mirror located on an incident light path, and configured to reflect an incident light to form a first reflected light; and a first three-dimensional rectangular coordinates system (X,Y,Z) is defined by a primary mirror vertex as a first origin;
a secondary mirror located on a first reflected light path, and configured to reflect the first reflected light to form a second reflected light; a secondary mirror reflecting surface is a stop surface; and a second three-dimensional rectangular coordinates system is defined by a secondary mirror vertex as a second origin; and the second three-dimensional rectangular coordinates system is obtained by moving the first three-dimensional rectangular coordinates system (X,Y,Z) along a Z-axis negative direction;
a tertiary mirror located on a second reflected light path, and configured to reflect the second reflected light to form a third reflected light; a third three-dimensional rectangular coordinates system is defined by a tertiary mirror vertex as a third origin; and the third three-dimensional rectangular coordinates system is obtained by moving the second three-dimensional rectangular coordinates system along a-Z-axis positive direction; and
a detector is located on a third reflected light path and configured to receive the third reflected light;
wherein a primary mirror surface is an xy polynomial surface up to the fifth order in the first three-dimensional rectangular coordinates system (X,Y,Z); a secondary mirror surface is an xy polynomial surface up to the fifth order in the second three-dimensional rectangular coordinates system; and a tertiary mirror surface is an xy polynomial surface up to the fifth order in the third three-dimensional rectangular coordinates system.

2. The system as claimed in claim 1 , wherein an xy polynomial surface equation 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
3

+

A
10

⁢

x
4

+

A
12

⁢

x
2

⁢

y
2

+

A
14

⁢

y
4

+

A
16

⁢

x
4

⁢
y

+

A
18

⁢

x
2

⁢

y
3

+

A
20

⁢

y
5

,

wherein, z represents surface vector high, c represents surface curvature, k represents conic constant, and A 2 ˜A 20 represents represent coefficients.

3. The system as claimed in claim 2

Assignees

• Univ Tsinghua
• Hon Hai Prec Ind Co Ltd

Inventors

• Zhu Jun
• Yang Tong
• Jin Guo-Fan
• Fan Shou-Shan

Classifications

• G01J1/42

  using electric radiation detectors (optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10) · CPC title

• G02B17/0642 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