Through-cloud celestial sighting system

Patent metadata

Field	Value
Publication number	US-2018372496-A1
Application number	US-201816018846-A
Country	US
Kind code	A1
Filing date	Jun 26, 2018
Priority date	Jun 26, 2017
Publication date	Dec 27, 2018
Grant date	—

Abstract

A wide field-of-view celestial sighting system and method are provided. The method includes orienting an imaging optic to collect light from at least one light source, such as at least one celestial body, the imaging optic being secured to a platform. The method further includes selectively collecting light from the at least one celestial body through a selective light collector secured to the platform and positioned in an imaging surface, such as an imaging plane, of the imaging optic. The method further includes combining forward scattered light from the at least one celestial body to provide a combined forward scattered light, and detecting a light intensity of the combined forward scattered light. Systems for performing the method are provided.

First claim

What is claimed is:

1 . A wide field-of-view celestial sighting system for viewing a plurality of light sources, the system comprising:
a platform; an imaging optic secured to the platform and configured to focus light from a plurality of light sources onto an imaging surface; a selective light collector secured to the platform and positioned in the imaging surface of the imaging optic, the selective light collector configured to allow forward scattered light from each of the plurality of light sources to pass through the selective light collector; and a light detector configured to receive the forward scattered light from the selective light collector and configured to sense an intensity of the forward scattered light.

2 . The system of claim 1 , wherein the imaging surface is an imaging plane.

3 . The system of claim 2 , further comprising:
at least one selective light collector actuator; and at least one processor configured to cause the at least one selective light collector actuator to maximize the intensity of the forward scattered light sensed by the light detector by at least one of:
rotating the selective light collector about one or more axes; and
translating the selective light collector,
the at least one processor being further configured to determine a navigational parameter based on one or more of a position and an orientation of the selective light collector.

4 . The system of claim 3 , wherein the at least one selective light collector actuator is configured to cause the selective light collector to oscillate within the imaging plane.

5 . The system of claim 3 , wherein the one or more axes includes two orthogonal axes.

6 . The system of claim 1 , wherein the selective light collector is a liquid crystal display (LCD).

7 . The system of claim 6 , further comprising:
at least one processor configured to maximize the intensity of forward scattered light sensed by the light detector by at least one of activating and deactivating one or more pixels in the LCD, and to determine a navigational parameter based on a set of pixels that are deactivated when a maximum intensity of forward scattered light is sensed by the light detector.

8 . The system of claim 1 , wherein the selective light collector is configured to allow only forward scattered light from each of the plurality of light sources to pass through the selective light collector, and is configured to block light from any other light sources from passing through the selective light collector.

9 . The system of claim 2 , wherein the selective light collector is a plurality of optical fibers each having a first end and a second end, the first end positioned to collect the forward scattered light from the imaging plane, and the second end positioned to direct the forward scattered light to the light detector.

10 . The system of claim 9 , wherein one of the first ends is individually movable within the imaging plane, and the system further comprises a cable actuator configured to move the one of the first ends.

11 . The system of claim 1 , further comprising a collection optic, wherein the selective light collector is a mask with a plurality of holes, and the mask is positioned between the collection optic and the imaging optic.

12 . The system of claim 1 , wherein the imaging optic is a ball lens.

13 . The system of claim 1 , wherein the light detector is a single pixel.

14 . A method of wide field-of-view celestial sighting for detecting light from at least one light source, the method comprising:
orienting an imaging optic to collect light from at least one light source, the imaging optic secured to a platform; selectively collecting light from the at least one light source through a selective light collector secured to the platform and positioned in an imaging surface of the imaging optic; combining forward scattered light from the at least one light source to provide a combined forward scattered light; and detecting a light intensity of the combined forward scattered light.

15 . The method of claim 14 , further comprising maximizing the light intensity of the combined forward scattered light that passes through the selective light collector by at least one of:
rotating the selective light collector about one or more axes; and translating the selective light collector.

16 . The method of claim 15 , wherein the one or more axes includes two orthogonal axes.

17 . The method of claim 14 , further comprising
oscillating the selective light collector about an orientation set point that is matched to an optimal orientation having a maximum detected light intensity of the combined forward scattered light; detecting fluctuations in the light intensity based on oscillation of the selective light collector; and adjusting the orientation set point to maximize the light intensity when the optimal orientation changes.

18 . The method of claim 17 , further comprising determining a navigational parameter based on an adjustment to the orientation set point.

19 . The method of claim 14 , wherein the selective light collector is an LCD, and the method further comprises determining a navigational parameter based on a set of pixels of the LCD that are deactivated when a maximum intensity of the combined forward scattered light is sensed by the detector.

20 . The method of claim 14 , wherein the selective light collector is an LCD and the platform is supported on a frame, and the method further comprises compensating for rotation of the frame by selectively activating pixels of the LCD.

Assignees

• Charles Stark Draper Laboratory Inc

Inventors

• Laine Juha-Pekka J
• Smith Stephen P

Classifications

• G01S17/66

  Tracking systems using electromagnetic waves other than radio waves · CPC title

• G01S17/88

  Lidar systems specially adapted for specific applications · CPC title

• G01C21/025 Primary

  with the use of startrackers · CPC title

• G02B6/06

  the relative position of the fibres being the same at both ends, e.g. for transporting images · CPC title

• G02F1/29

  for the control of the position or the direction of light beams, i.e. deflection · CPC title