Boresight error monitor for laser radar integrated optical assembly
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01J-001/00
G01S-007/497
G01S-007/481
출원번호
US-0010375
(2013-08-26)
등록번호
US-9587977
(2017-03-07)
발명자
/ 주소
Smith, Daniel G.
Novak, W. Thomas
출원인 / 주소
Nikon Corporation
대리인 / 주소
Klarquist Sparkman, LLP
인용정보
피인용 횟수 :
0인용 특허 :
4
초록▼
Boresight and other pointing errors are detected based on a monitor beam formed by diverting a portion of a probe beam. The monitor beam is directed to a position sensitive photodetector, and the optical power received at the position sensitive photodetector is used to estimate or correct such point
Boresight and other pointing errors are detected based on a monitor beam formed by diverting a portion of a probe beam. The monitor beam is directed to a position sensitive photodetector, and the optical power received at the position sensitive photodetector is used to estimate or correct such pointing errors.
대표청구항▼
1. An optical measurement system for determining a target dimension, comprising: a measurement beam source configured to produce a measurement beam;a measurement beam optical system configured to direct the measurement beam at a target, the measurement beam optical system including a moveable focus
1. An optical measurement system for determining a target dimension, comprising: a measurement beam source configured to produce a measurement beam;a measurement beam optical system configured to direct the measurement beam at a target, the measurement beam optical system including a moveable focus element for focusing the measurement beam at the target;a beam splitter configured to select a portion of the measurement beam after propagating through the movable focus element so as to form a monitor beam;a monitor beam photodetection system configured to receive the monitor beam and provide an indication of a measurement beam pointing error that is associated with the movement of the moveable focus element; anda measurement beam photodetection system configured to estimate the target dimension and a coordinate associated with a target location of the target based on a portion of the measurement beam returned from the target, wherein at least one of the estimated coordinate or the target location is adjusted based on the indicated pointing error. 2. The optical measurement system of claim 1, further comprising a bifurcated mirror configured to direct at least portions of the monitor beam to the monitor beam detection system. 3. The optical measurement system of claim 1, wherein the moveable focus element is a corner cube. 4. The optical measurement system of claim 1, wherein the measurement beam optical system includes at least one lens configured to shape the measurement for delivery to the target, and the beam splitter is situated to form the monitor beam based on the shaped measurement beam. 5. The optical measurement system of claim 4, wherein the monitor beam photodetection system includes a multi-element photodetector, and the beam splitter is configured to direct the monitor beam to the multi-element detector. 6. The optical measurement system of claim 5, further comprising a monitor beam lens situated to receive the monitor beam from the beam splitter and direct the monitor beam to the multi-element detector. 7. The optical measurement system of claim 6, wherein the monitor beam lens includes a plurality of lens segments associated with at least two different curvatures and configured to direct monitor beam portions to respective elements of the multi-element detector. 8. The optical measurement system of claim 5, wherein the monitor beam photodetection system is configured to determine a pointing error based at least one monitor beam portion associated with a selected measurement beam focus. 9. The optical measurement system of claim 5, wherein the measurement beam source includes an optical fiber having an output surface configured to emit the measurement beam, and the monitor beam lens is situated to image the output surface of the optical fiber at the multi-element detector. 10. The optical measurement system of claim 9, wherein the multi-element photodetector is situated proximate the output surface of the optical fiber. 11. The optical measurement system of claim 5, wherein the multi-element photodetector is a quadrant photodetector. 12. The optical measurement apparatus of claim 6, further comprising a prism, wherein the monitor beam is situated to be directed at the prism so as to couple portions of the monitor beam to respective elements of the multi-element photodetector. 13. The optical measurement system of claim 5, further comprising a reflective surface situated to reflect the monitor beam received from the beam splitter to the multi-element photodetector. 14. The optical measurement system of claim 13, wherein the reflective surface includes a plurality of segments associated with corresponding curvatures, wherein monitor beam portions associated with the segments are directed to corresponding elements of the multi-element photodetector. 15. The optical measurement system of claim 14, wherein the monitor beam photodetection system is configured to determine a pointing error based at least one monitor beam portion associated with a selected measurement beam focus. 16. The optical measurement system of claim 5, further comprising a beam divider system configured to receive the monitor beam from the beam splitter and direct first and second monitor beam portions to the multi-element photodetector. 17. The optical measurement system of claim 16, wherein the beam divider system includes a cube beam splitter situated to direct the first monitor beam portion to the multi-element photodetector, and a reflector situated to receive the second monitor beam portion and direct the second monitor beam portion to the multi-element photodetector. 18. The optical measurement system of claim 17, wherein the reflector is situated to direct the second monitor beam portion to the multi-element photodetector by transmission through the cube beam splitter. 19. The optical measurement system of claim 16, wherein the beam divider system includes a cube beam splitter situated to direct the first monitor beam portion to a first reflector and the second monitor beam portion to a second reflector, and the first and second reflectors are situated to direct the first and second monitor beam portions to the multi-element photodetector. 20. The optical measurement system of claim 19, wherein the monitor beam photodetection system is configured to determine a pointing error based on interference between the first and second monitor beam portions. 21. The optical measurement system of claim 19, further comprising an auxiliary lens configured to direct the first and second monitor beam portions to the multi-element photodetector. 22. The optical measurement system of claim 21, wherein the monitor beam photodetection system is configured to determine a pointing error based on a distribution of optical power from the first and second monitor beam portions at the multi-element photodetector. 23. The optical measurement system of claim 22, wherein the auxiliary lens is bonded to the cube beam splitter and the reflective surface is a surface of the cube beam splitter. 24. The optical measurement apparatus of claim 1, further comprising a dual axis rotational stage configured to select a target location for the measurement beam, wherein the beam measurement beam optical system and the beam splitter are secured to the dual axis rotational stage. 25. A measurement method for determining a target dimension, comprising: obtaining a portion of a measurement beam directed toward a target from a moveable focus element situated to focus the measurement beam at the target, wherein the portion obtained provides a monitor beam;based on a propagation direction of the monitor beam, detecting a pointing direction of the measurement beam associated with a movement of the moveable focus element and determining a pointing error of the measurement beam that is associated with the movement of the moveable focus element; andestimating a coordinate associated with a selected location of the target and a dimension of the target based on a portion of the measurement beam returned from the target;wherein at least one of the estimated coordinate or the selected target location is adjusted based on the determined pointing error. 26. The method of claim 25, wherein the pointing direction is associated with a boresight error resulting from focusing, shaping, or pointing of the measurement beam. 27. The method of claim 25, further comprising determining the propagation direction of the monitor beam by directing the monitor beam to a plurality of detector elements, and measuring monitor beam power received at each of the plurality of detector segments. 28. The method of claim 27, wherein the detector segments are elements of a multi-element detector. 29. The method of claim 27, further comprising determining pointing errors for a plurality of focus positions of the measurement beam. 30. The method of claim 29, further comprising storing the determined pointing errors and the associated focus positions in a computer readable storage device. 31. The method of claim 26, further comprising determining the propagation direction of the monitor beam by directing the monitor beam to a position sensitive detector, and measuring monitor beam power received at the position sensitive detector. 32. The method of claim 25, wherein at least one of the estimated coordinate or the target location is adjusted based on a measurement beam focus distance. 33. The method of claim 25, wherein the portion of a measurement beam is obtained with a beam splitter to provide the monitor beam. 34. The method of claim 33, wherein the monitor beam is processed so as to produce a plurality of monitor beam portions, and based on a focus distance of the measurement beam, selecting one or more of the monitor beam portions to determine the pointing error of the measurement beam. 35. The method of claim 34, wherein the monitor beam portions are associated with different wavefront curvatures. 36. The method of claim 35, wherein the monitor beam portions are associated with different states of polarization. 37. The method of claim 25, wherein the monitor beam is divided into at least a first monitor beam portion and a second monitor beam portion, and the propagation direction is estimated based on interference fringes associated with interference between the first and second monitor beam portions. 38. The method of claim 25, further comprising adjusting a measurement beam pointing direction based the estimated beam pointing direction. 39. The method of claim 25, wherein the monitor beam is obtained with a beam splitter. 40. An optical measurement apparatus for determining a target dimension, comprising: a moveable focus element secured to a moveable stage so as to direct and focus a probe beam at a target;a probe beam photodetection system situated to determine the target dimension based on returned portions of the focused probe beam received from the target; anda monitor beam system configured to obtain a portion of the focused probe beam to produce a monitor beam, and based on the monitor beam, estimate a probe beam pointing error associated with a movement of the moveable focus element with the moveable stage;wherein the probe beam photodetection system is situated to estimate a coordinate associated with a selected location of the target based on a portion of the probe beam returned from the target, wherein at least one of the estimated coordinate or the selected location is adjusted based on the estimated probe beam pointing error. 41. The optical measurement apparatus of claim 40, wherein the monitor beam system includes a beam splitter configured to obtain the portion of the probe beam. 42. The optical measurement system of claim 1, wherein the moveable focus element is a lens. 43. The optical measurement system of claim 1, wherein the moveable focus element is situated to move along an optical axis of the measurement beam optical system so as to focus the measurement beam at the target. 44. The measurement method of claim 25, wherein the moveable focus element is situated to move along an optical axis of the measurement beam optical system so as to focus the measurement beam at the target. 45. The optical measurement apparatus of claim 40, wherein the moveable focus element is situated to move along an optical axis of the measurement beam optical system so as to focus the probe beam at the target.
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이 특허에 인용된 특허 (4)
Ball James M. (Huntington Beach CA) Richman Issac (Newport Beach CA), Active boresight drift measurement and calibration apparatus.
Appert Quentin D. (Los Alamos NM) Godfrey Thomas E. (Orange CA) Hammond David L. (Newport Beach CA) McFerson Gary O. (Santa Ana CA) Odum Richard F. (Placentia CA) Ottoson Raymond H. (Riverside CA), Automatic boresight compensation device.
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