Off-axis hybrid surface three-mirror optical system

• US 10,642,010 B2
• Filed: 12/14/2017
• Issued: 05/05/2020
• Est. Priority Date: 01/24/2017
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Original Assignee: Tsinghua University
• Inventors: Zhu, Jun, Gong, Tong-Tong, Jin, Guo-Fan, Fan, Shou-Shan
• Primary Examiner(s): Allen, Stephone B
• Assistant Examiner(s): Abdur, Rahman
• Application Number:
  US15/842,834
• Publication Number:
  US 20180210180A1
• Time in Patent Office: 873 Days
• Field of Search: 359858
• CPC Class Codes: G02B 17/0621 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 Class Codes: G02B 17/0642 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 Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines

Abstract

An off-axis hybrid surface three-mirror optical system comprises a primary mirror, a secondary mirror, a tertiary mirror, and an image sensor. A reflective surface of the primary mirror is a sixth-order polynomial freeform surface of xy. A reflective surface of the secondary mirror is a sixth-order polynomial aspheric surface of xy. A reflective surface of the a tertiary mirror is a spherical surface of xy.

Claims

1. An off-axis hybrid surface three-mirror optical system comprising:

a primary mirror located on an outgoing light path of rays;

a secondary mirror located on a first reflected light path, which is emitted from the primary mirror;

a tertiary mirror located on a second reflected light path, which is emitted from the secondary mirror; and

an image sensor located on a third reflected light path, which is emitted from the tertiary mirror;

wherein a first three-dimensional rectangular coordinates system (x₁ y₁, z₁) is defined in space;

relative to the first three-dimensional rectangular coordinates system (x₁,y₁, z₁), a second three-dimensional rectangular coordinates system (x₂ y₂ z₂) is defined by a primary mirror location, a third three-dimensional rectangular coordinates system (x₃, y₃, z₃) is defined by a secondary mirror location, and a fourth three-dimensional rectangular coordinates system (x₄ y₄, z₄) is defined by a tertiary mirror location;

in the second three-dimensional rectangular coordinates system (x₂, y₂, z₂), a reflective surface of the primary mirror is a sixth-order polynomial freeform surface of x₂y₂;

in the third three-dimensional rectangular coordinates system (x₃, y₃, z₃), a reflective surface of the secondary mirror is a sixth-order polynomial aspheric surface of x₃y₃, and the sixth-order polynomial aspheric surface of x₃ y₃ is;

2. The system as claimed in claim 1, wherein a second origin of the second three-dimensional rectangular coordinates system (x₂, y₂, z₂) in the first three-dimensional rectangular coordinates system (x₁, y₁, z₁) is (0, 244.51, 193.62).

3. The system as claimed in claim 2, wherein an z₂-axis positive direction rotates about 13.39 degrees along a counterclockwise direction relative to an z₁-axis positive direction.

4. The system as claimed in claim 1, wherein a third origin of the third three-dimensional rectangular coordinates system (x₃, y₃, z₃) in the first three-dimensional rectangular coordinates system (x₁, y₁, z₁) is (0, 0, -100).

5. The system as claimed in claim 4, wherein an z₃-axis positive direction rotates about 15 degrees along a counterclockwise direction relative to an z₁-axis positive direction.

6. The system as claimed in claim 1, wherein a fourth origin of the fourth three-dimensional rectangular coordinates system (x₄, y₄, z₄) in the first three-dimensional rectangular coordinates system (x₁, y₁, z₁) is (0, -160.83, 209.49).

7. The system as claimed in claim 6, wherein an z₄-axis positive direction rotates about 0 degrees along a counterclockwise direction relative to an z₁-axis positive direction.

8. The system as claimed in claim 1, wherein the sixth-order polynomial freeform

9. The system as claimed in claim 1, wherein the spherical surface of x₄y₄ is:

(x−

A)²+(y−

B)²+(z−

c)²=r ², A=0, B=−

160.83, C=209.49, and r=−

988.48.

10. The system as claimed in claim 1, wherein a fifth three-dimensional rectangular coordinates system (x₅, y₅, z₅) is defined by an image sensor location, a fifth origin of the fifth three-dimensional rectangular coordinates system (x₅, y₅, z₅) in the first three-dimensional rectangular coordinates system (x₁, y₁, z₁) is (0, -145.13, -174.41), and an z₅-axis positive direction rotates about 10 degrees along a counterclockwise direction relative to an z₁-axis positive direction.

11. The system as claimed in claim 1, wherein a length of the off-axis hybrid surface three-mirror optical system along a y₁-axis is about 430 millimeters.

12. The system as claimed in claim 11, wherein a length of the off-axis hybrid surface three-mirror optical system along a z₁-axis is about 400 millimeters.

13. The system as claimed in claim 1, wherein a field angle of the hybrid surface three-mirror optical system is about 3°

×

6°

.

14. The system as claimed in claim 13, wherein an angle in an horizontal direction is in a range from about −

1.5°

to about 1.5°

.

15. The system as claimed in claim 13, wherein an angle in a vertical direction is in a range from about −

16°

to about −

10°

.

16. The system as claimed in claim 1, wherein an effective focal length of the hybrid surface three-mirror optical system is about 220 millimeters.

17. The system as claimed in claim 1, wherein an F-number is about 2.2.

18. An off-axis hybrid surface three-mirror optical system comprising:

a primary mirror located on an outgoing light path of rays;

a secondary mirror located on a first reflected light path, which is emitted from the primary mirror;

a tertiary mirror located on a second reflected light path, which is emitted from the secondary mirror; and

an image sensor located on a third reflected light path, which is emitted from the tertiary mirror;

wherein a first three-dimensional rectangular coordinates system (x₁, y₁, z₁) is defined in space;

relative to the first three-dimensional rectangular coordinates system (x₁,y₁, z₁), a second three-dimensional rectangular coordinates system (x₂ y₂ z₂) is defined by a primary mirror location, a third three-dimensional rectangular coordinates system (x₃, y₃, z₃) is defined by a secondary mirror location, and a fourth three-dimensional rectangular coordinates system (x₄ y₄, z₄) is defined by a tertiary mirror location;

in the second three-dimensional rectangular coordinates system (x_z, y_z, z₂), a reflective surface of the primary mirror is a sixth-order polynomial freeform surface of x₂y₂;

in the third three-dimensional rectangular coordinates system (x₃, y₃, z₃), a reflective surface of the secondary mirror is a sixth-order polynomial aspheric surface of x₃y₃; and

in the fourth three-dimensional rectangular coordinates system (x₄, y₄, z₄), a reflective surface of the tertiary mirror is a spherical surface of x₄y₄.

19. The system as claimed in claim 18, wherein the sixth-order polynomial freeform