Remote optical position sensing device and methods

Patent metadata

Field	Value
Publication number	US-9423277-B2
Application number	US-201414564833-A
Country	US
Kind code	B2
Filing date	Dec 9, 2014
Priority date	Dec 9, 2014
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

An optical position sensing system and method for sensing a gimbal position in a gimbal-based optical system. One example of an optical position sensing system includes an off-gimbal light source that generates a position sensing light beam and transmits the position sensing light beam along an optical coude path of the optical system, and an on-gimbal optical element that causes a change in an intensity of the position sensing light beam based on rotation of the gimbal about the axis. The system further includes an off-gimbal detector configured to receive the position sensing light beam returned from the optical element and to detect the change in the intensity of the position sensing light beam, and a controller coupled to the detector and configured to determine the gimbal position based on a correlation between the change in the intensity of the position sensing light beam and the gimbal position.

First claim

What is claimed is:

1. An optical position sensing system for sensing a gimbal position in a gimbal-based optical system comprising:
a light source configured to generate a position sensing light beam, the light source being mounted off-gimbal in the optical system and further configured to transmit the position sensing light beam along an optical coude path of the optical system;
an optical element mounted on an axis of the gimbal and configured to cause a change in an intensity of the position sensing light beam based on rotation of the gimbal about the axis;
a detector mounted off-gimbal in the optical system and configured to receive the position sensing light beam returned from the optical element and to detect the change in the intensity of the position sensing light beam; and
a controller coupled to the detector and configured to determine the gimbal position based on a correlation between the change in the intensity of the position sensing light beam and the gimbal position.

2. The optical position sensing system of claim 1 , wherein the optical element is a continuously varying neutral density filter.

3. The optical position sensing system of claim 1 , further comprising a first polarizer positioned off-gimbal in an optical path of the position sensing light beam, and wherein the optical element is a second polarizer.

4. The optical position sensing system of claim 3 , wherein the first polarizer is positioned in front of the detector.

5. The optical position sensing system of claim 1 , further comprising a mirror disposed behind the optical element and configured to reflect the position sensing light beam back along the coude path.

6. The optical position sensing system of claim 1 , further comprising a first beam-splitter configured to couple the position sensing light beam from the light source into the coude path, and to direct the position sensing light beam returned from the coude path toward the detector.

7. The optical position sensing system of claim 6 , further comprising a second beam-splitter disposed between the light source and the first beams-splitter, and configured to transmit the position sensing light beam from the light source to the first beam-splitter, and to reflect the position sensing light beam returned from the coude path via the first beam-splitter toward the detector.

8. The optical position sensing system of claim 1 , wherein the detector is a silicon intensity detector.

9. The optical position sensing system of claim 1 , wherein the light source is a laser light source.

10. The optical position sensing system of claim 9 , further comprising:
a local oscillator located off-gimbal and configured to produce a modulation signal;
a laser driver coupled to the local oscillator and to the laser light source, and configured to drive the laser light source to produce a modulated position sensing light beam;
a demodulator coupled to the local oscillator and to the detector, and configured to demodulate an output signal from the detector using the modulation signal to produce a demodulated signal, the demodulated signal including information corresponding to the change in the intensity of the position sensing light beam; and
an analog to digital converted configured to receive the demodulated signal and to produce a digital version of the demodulated signal;
wherein the controller is configured to receive and process the digital version of the demodulated signal to determine the gimbal position.

11. The optical position sensing system of claim 10 , further comprising an amplifier positioned between the detector and the demodulator and configured to amplify the output signal from the detector to produce an amplified output signal, and wherein the demodulator is configured to demodulate the amplified output signal.

12. A method of sensing a gimbal position in a gimbal-based optical system, the method comprising:
directing a position sensing light beam along an optical coude path of the optical system to an optical element mounted to a gimbal axis;
altering an intensity of the position sensing light beam with the optical element;
receiving the position sensing light beam returned from the optical element via the coude path at a detector located off-gimbal;
detecting, with the detector, the intensity of the position sensing light beam; and
determining the gimbal position based on a known correlation between the intensity of the position sensing light beam and an angular position of the gimbal.

13. The method of claim 12 , further comprising generating the position sensing light beam using a laser light source.

14. The method of claim 13 , wherein generating the position sensing light beam includes generating a modulated position sensing light beam using the laser light source.

15. The method of claim 14 , further comprising demodulating an output signal from the detector, the output signal including information corresponding to the intensity of the position sensing light beam.

Assignees

• Raytheon Co

Inventors

• Anthony David G
• Koehler Elka E
• Taylor Byron B
• Rinker Robert

Classifications

• G01D5/30 Primary

  the beams of light being detected by photocells · CPC title

• G01D5/34 Primary

  the beams of light being detected by photocells · CPC title