Quadrant light detector

• US 5,877,490 A
• Filed: 08/07/1997
• Issued: 03/02/1999
• Est. Priority Date: 01/23/1996
• Status: Expired due to Term

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Advanced Optical Technologies, LLC
• Inventors: Rains, Jack C. Jr., Ramer, David P.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US08/908,677
• Time in Patent Office: 572 Days
• Field of Search: 356/121, 356/375, 356/139.01, 250/203.1, 250/203.3, 250/203.4, 250/203.6, 250/206.1
• US Class Current: 250/206.1
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/7835 using coding masks
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G01S 7/4816 of receivers alone

Abstract

A quadrant light detector that employs the concept of constructed occlusion to improve its accuracy and by incorporating baffles within the design to improve its detection response to incoming light having an incidence angle neat the horizon, and to divide a diffusely reflective cavity into quadrants. The quadrant detector is able to determine the direction, or azimuth and elevation, to the light source anywhere within a sector of a hemisphere or a sphere.

Claims

1. A system for determining the direction of incoming light, comprising:

a base having a diffusely reflective surface;

a diffusely reflective baffle defining a plurality of reflective regions in relation to the diffusely reflective surface of the base;

a mask spaced a predetermined distance away from the diffusely reflective surface of the base, the mask occluding a portion of light directed toward the reflective regions;

a sensor mechanism optically coupled to the reflective regions capable of detecting intensity of light in each of the reflective regions; and

a processor coupled to the sensor mechanism, for generating signals representing the direction of the incoming light in two directions in response to the detected intensity of light in each of the reflective regions.

2. A system as in claim 1, wherein the sensor mechanism comprises a plurality of light sensors, at least one of the light sensors being coupled to receive light incident on each one of the reflective regions and generating a response signal based on intensity of light incident on its respective reflective region, and the processor is responsive to signals from the light sensors.

3. A system as in claim 1, wherein the baffle defines at least four reflective regions.

4. A system as in claim 1, wherein the diffusely reflective surface of the base comprises a cavity formed in the base having a diffusely reflective surface and an aperture facing the mask.

5. A system as in claim 1, further comprising a display for displaying the direction of the incoming light based on the signals from the processor.

6. A light detector for sensing the incoming direction of incident light, comprising:

a base having a diffusely reflective surface;

a mask situated a predetermined distance from the diffusely reflective surface of the base, the mask having a diffusely reflective surface facing the diffusely reflective surface of the base;

a diffusely reflective cavity formed in one of the diffusely reflective surfaces;

a reflective baffle located in a region between the diffusely reflective surfaces for dividing the region into sections; and

a light detection system coupled to the sections to generate one or more signals responsive to intensity of light incident on respective sections.

7. A light detector as in claim 6, wherein the cavity is formed in the base and has an aperture facing toward the diffusely reflective surface of the mask.

8. A light detector as in claim 6, wherein the cavity is substantially hemispherical.

9. A light detector for sensing the incoming direction of incident light, comprising:

a base having a diffusely reflective cavity formed in a surface thereof, an opening of said cavity defining an aperture;

a mask having a diffusely reflective surface facing the aperture and spaced a predetermined distance from the aperture;

a baffle disposed in a region between the aperture and the diffusely reflective surface of the mask for subdividing the region into sections;

a plurality of photodectectors mounted on the mask, each photodetector positioned to receive light directed toward the diffusely reflective surface of the mask through a respective one of the sections for generating a signal representative of intensity of incident light received by the photodetector through the respective section.

10. A light detector as in claim 9, wherein the baffle extends into and subdivides the cavity.

11. A light detector as in claim 9, wherein the cavity is substantially hemispherical.

12. A light detector as in claim 9, wherein the baffle divides the region into at least four of said sections.

13. A light detector for sensing the incoming direction of incident light over a substantially spherical field of view, comprising:

a base having first and second faces on opposite sides thereof, a first diffusely reflective cavity formed in the first face defining a first aperture and a second diffusely reflective cavity formed in the second face defining a second aperture;

a first mask having a diffusely reflective surface facing the first aperture and spaced a predetermined distance from the first aperture;

a first baffle disposed in a region between the first aperture and the diffusely reflective surface of the first mask for subdividing the region into first sections;

a second mask having a diffusely reflective surface facing the second aperture and spaced a predetermined distance from the second aperture;

a second baffle disposed in a region between the second aperture and the diffusely reflective surface of the second mask for subdividing the region between the second aperture and the diffusely reflective surface of the second mask into second sections; and

a sensor mechanism optically coupled to the first and second sections capable of detecting intensity of light in each of the first and second sections.

14. A light detector as in claim 13, wherein the sensor mechanism comprises:

a plurality of first photodectectors mounted on the first mask, each first photodetector positioned to receive light directed toward the diffusely reflective surface of the first mask through a respective one of the first sections for generating a signal representative of intensity of incident light received by the first photodetector through the respective first section; and

a plurality of second photodectectors mounted on the second mask, each second photodetector positioned to receive light directed toward the diffusely reflective surface of the second mask through a respective one of the second sections for generating a signal representative of intensity of incident light received by the second photodetector through the respective second section.

15. A light detector as in claim 14, wherein the first and second cavities are substantially hemispherical.

16. An arrangement for detecting direction of incoming light, comprising:

a base having a defined diffusely reflective region for receiving and reflecting incoming light;

a mask positioned to occlude a portion but not all of the diffusely reflective region with respect to a sector from which the arrangement may receive the incoming light, the mask having a diffusely reflective surface facing the diffusely reflective region;

a diffusely reflective cavity formed in one of the diffusely reflective region and the diffusely reflective surface, the cavity forming an aperture;

a baffle dividing the aperture into predefined sections;

a sensor mechanism optically coupled to the predefined sections capable of detecting intensity of light in each of the predefined sections; and

a processor coupled to the sensor mechanism, for determining the direction of the incoming light with respect to the arrangement in response to the detected intensity of light in each of the predefined sections.

17. An arrangement as in claim 16, wherein the processor generates signals representing the direction of the incoming light in two directions in response to the detected intensity of light in each of the predefined sections.

18. An arrangement as in claim 17, further comprising a display for displaying the direction of the incoming light based on the signals representing the direction of the incoming light in two directions from the processor.

19. An arrangement as in claim 16, wherein the baffle divides the aperture into at least four of the predefined sections.

20. An arrangement as in claim 16, wherein the sensor mechanism comprises a plurality of light detectors, wherein each of the light detectors is coupled to receive light from one of the predefined sections.

21. An arrangement as in claim 20, wherein each of the light detectors is mounted on the mask so as to receive and detect light directed toward the diffusely reflective surface of the mask.

22. An arrangement as in claim 16, wherein the cavity is formed in the base.

23. An arrangement as in claim 22, wherein the cavity is substantially hemispherical.