Off-axial three-mirror optical system with freeform surfaces

Patent metadata

Field	Value
Publication number	US-9405109-B2
Application number	US-201514726687-A
Country	US
Kind code	B2
Filing date	Jun 1, 2015
Priority date	Jun 3, 2014
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

An off-axial three-mirror optical system with freeform surfaces includes an aperture, a primary mirror, a secondary mirror, a tertiary mirror, and a detector. The aperture is located on an incident light path. The primary mirror is located on an aperture transmitted light path. The secondary mirror is located on a primary mirror reflected light path. The tertiary mirror is located on a secondary mirror reflected light path. The detector located on a tertiary mirror reflected light path. A primary mirror surface and a tertiary mirror surface have a same freeform surface equation, and the freeform surface equation is a sixth order x′y′ polynomial. A secondary mirror surface is a tenth order aspherical surface.

First claim

What is claimed is:

1. An off-axial three-mirror optical system with freeform surfaces comprising:
an aperture located on an incident light path;
a primary mirror located on the incident light path and configured to reflect incident lights transmitting through the aperture to form a first reflected light;
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 tertiary mirror located on a second reflected light path and configured to reflect the second reflected light to form a third reflected light; and
a detector located on a third reflected light path and configured to receive the third reflected light;
wherein a first three-dimensional rectangular coordinates system (X,Y,Z) is defined by a secondary mirror location, and a secondary mirror vertex is a first three-dimensional rectangular coordinates system (X,Y,Z) origin; a second three-dimensional rectangular coordinates system (X′,Y′,Z′) is defined by a primary mirror location and a tertiary mirror location, and the second three-dimensional rectangular coordinates system (X′,Y′,Z′) is obtained by moving the first three-dimensional rectangular coordinates system (X,Y,Z) along a Z-axis positive direction; a primary mirror surface and a tertiary mirror surface have a same freeform surface equation, and the freeform surface equation is an x′y′ polynomial up to a sixth order; and a secondary mirror surface is an aspherical surface up to a tenth order.

2. The system as claimed in claim 1 , wherein the x′y′ polynomial up to the sixth order 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

⁢

Assignees

• Univ Tsinghua
• Hon Hai Prec Ind Co Ltd

Inventors

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

Classifications

• 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