Compact laser radar corner cube

Patent metadata

Field	Value
Publication number	US-9964745-B2
Application number	US-201313830169-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Aug 31, 2012
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

Focus assemblies for laser radar are situated to receive a measurement beam that is focused at or in the focus assemblies. In some examples, focus assemblies include a corner cube and a return reflector, and the measurement beam is focused on, at, or within the corner cube or return reflector. A polarizing beam splitter and a quarter wave plate can be situated so that an input measurement beam and an output measurement beam can be separated.

First claim

I claim:

1. An optical system, comprising:
a focus relay optical system configured to direct a measurement light flux propagating along an axis toward a focus along the axis;
an objective lens system; and
a focus adjustment system that receives the measurement light flux from the focus relay optical system and directs the measurement light flux to the objective lens system, wherein the focus adjustment system includes at least one optical element that is moveable along the axis; and
wherein the focus adjustment system is configured so that a propagation distance of the measurement light flux between the focus relay optical system and the objective lens system along the axis is variable so that the focus relay optical system and the objective lens system adjust the focus along the axis so that the focus is moveable along the axis.

2. The optical system of claim 1 , wherein the focus relay optical system is configured to direct the measurement light flux propagating along the axis so that the focus is within the focus adjustment system.

3. The optical system of claim 1 , wherein the focus adjustment system includes a corner cube translatable along the axis and a return reflector, wherein the focus relay optical system is configured to direct the measurement light flux propagating along the axis so that the focus is within the corner cube.

4. The optical system of claim 1 , wherein the focus adjustment system includes a corner cube translatable along the axis and a return reflector, wherein the focus relay optical system is configured to direct the measurement light flux propagating along the axis so that the focus is between the corner cube and the return reflector.

5. The optical system of claim 1 , wherein the relay optical system is configured to establish the focus along the axis on a target-side portion of the optical path in the corner cube associated with propagation of the measurement beam from the return reflector.

6. The optical system of claim 1 , wherein the focus is at a free space portion of the optical path.

7. The optical system of claim 1 , wherein the focus is situated between the objective lens system and the beam splitting system.

8. The optical system of claim 1 , further comprising a beam splitting system configured to direct at least a portion of the measurement light flux to the focus adjustment system and at least a portion of the measurement light flux from the focus adjustment system to the objective lens system.

9. The optical system of claim 8 , wherein the focus adjustment system includes a corner cube and a return reflector, wherein the corner cube is translatable along the axis.

10. The optical system of claim 9 , wherein the beam splitting system includes a polarizing beam splitter (PBS) and at least one wave plate situated so that the measurement light flux in a first state of polarization is delivered to the PBS and received by the PBS from the focus assembly in a second state of polarization that is orthogonal to the first state of polarization.

11. The optical system of claim 10 , wherein the at least one wave plate is a ¼ wave retarder.

12. The optical system of claim 11 , where the at least one wave plate is situated along the axis between the PBS and the corner cube.

13. The optical system of claim 11 , where the at least one wave plate is situated along the axis between the return reflector and the corner cube.

14. The optical system of claim 10 , wherein the at least one wave plate includes a first wave plate situated between the PBS and the corner cube along the axis, and a second wave plate situated along the axis between the corner cube and the return reflector.

15. The optical system of claim 10 , wherein the PBS is configured to reflect the measurement light flux to the corner cube.

16. The optical system of claim 10 , wherein the PBS is configured to transmit the measurement light flux to the corner cube.

17. The optical system of claim 10 , wherein the focus relay optical system includes at least one lens situated to direct the measurement flux into the PBS.

18. The optical system of claim 10 , wherein the focus relay optical system includes at least one lens situated to receive the measurement flux from the PBS and converge the measurement flux into the focus adjustment optical system.

19. The optical system of claim 9 , wherein the focus relay optical system includes a lens situated along the axis between the corner cube and the return reflector.

20. The optical system of claim 9 , wherein the return reflector is convex or concave.

21. A distance measuring apparatus, comprising:
the optical system of claim 1 ;
a detector situated to receive a portion of the measurement light flux that is reflected by the target; and
a controller configured to measure a distance to the target based on the received portion of the measurement light flux.

22. A laser system, comprising:
an optical fiber coupled to the at least one laser and configured to emit a measurement beam from the laser along an axis;
a focus relay optical system configured to receive the measurement beam from the optical fiber and direct the measurement beam to a first focus along the axis;
a focusing assembly that includes at least one moveable optical element, the focusing assembly configured to receive the measurement beam from the focus relay optical system; and
an objective lens situated so as to receive the measurement beam from the focusing assembly and direct a focused measurement beam to a target with a second focus along the axis.

23. The laser system of claim 22 , further comprising a beam splitting optical assembly, wherein the focus relay optical system is situated to direct the measurement beam to the beam splitting optical system.

24. The laser system of claim 22 , further comprising a beam splitting optical assembly, wherein the focus relay optical system is situated to receive the measurement beam from the beam splitting optical system.

25. The laser system of claim 22 , wherein the focus relay optical system is configured to converge the measurement beam.

26. The laser system of claim 22 , wherein the focus relay optical system is configured to focus the measurement beam within the focusing assembly.

27. The laser system of claim 26 , wherein the focus relay optical system is configured to focus the measurement beam along a target-side portion of a variable optical path of the measurement beam along the axis that varies based on a movement of the moveable optical element.

28. The laser radar system of claim 22 , further comprising a detection system configured to receive the measurement beam from the target with the optical fiber and produce an estimate of a target distance.

29. The system of claim 22 , wherein the at least one moveable optical element of the focusing assembly includes a retroreflector and the focusing assembly includes a return reflector, wherein the movement of the retroreflector is configured to establish a variable optical path of the measurement beam along the axis.

30. The system of claim 29 , wherein the return reflector is fixed.

31. The system of claim 29 , wherein the return reflector is fixed and the retroreflector is a corner cube.

32. The system of claim 29 , wherein:
the retroflector is a corner cube;
the optical fiber i

Assignees

• Nikon Corp

Inventors

• Smith Daniel G

Classifications

• G01B11/14

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G02B27/283

  used for beam splitting or combining · CPC title

• G01S7/4814

  of transmitters alone · CPC title

• G02B17/0876 Primary

  for light collecting, e.g. for use with a detector · CPC title

• G01S17/08 Primary

  for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) · CPC title