APPARATUS AND METHOD FOR A LIGHT DIRECTION SENSOR

• US 20100208245A1
• Filed: 02/19/2009
• Published: 08/19/2010
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Leviton, Douglas B.
• Granted Patent: US 7,924,415 B2
• Time in Patent Office: Days
• US Class Current: 356/139.20
• CPC Class Codes: B64G 1/363 using sun sensors
• CPC Class Codes: G01C 21/025 with the use of startrackers
• CPC Class Codes: G01D 5/363 Direction discrimination
• CPC Class Codes: G01S 3/7835 using coding masks
• CPC Class Codes: G01S 3/7862 mounted on a moving platform, e.g. space vehicle

Abstract

The present invention provides a light direction sensor for determining the direction of a light source. The system includes an image sensor; a spacer attached to the image sensor, and a pattern mask attached to said spacer. The pattern mask has a slit pattern that as light passes through the slit pattern it casts a diffraction pattern onto the image sensor. The method operates by receiving a beam of light onto a patterned mask, wherein the patterned mask as a plurality of a slit segments. Then, diffusing the beam of light onto an image sensor and determining the direction of the light source.

Claims

1. A light direction sensor, comprising:

a image sensor;

a spacer attached to said image sensor; and

a pattern mask having a plurality of slits, and is attached to said spacer, wherein said pattern mask has a slit pattern that as light passes through the slit pattern the light casts a diffraction pattern onto the image sensor.

2. The light direction sensor of claim 1, further comprising an interface substrate.

3. The light direction sensor of claim 1, wherein said pattern mask is a perforated metal foil.

4. The light direction sensor of claim 1, wherein said slit pattern further comprises an arrangement of slits which form a Cartesian grid.

5. The light direction sensor of claim 4, wherein said slits has a width in a range between 3 and 20 μ

m.

6. The light direction sensor of claim 5, wherein said slits have the width that is approximately 10 μ

m.

7. The light direction sensor of claim 4, wherein said slits have spacing between the slits in the range of 100 to 800 μ

m.

8. The light direction sensor of claim 1, wherein said spacing provides a gap between said image sensor and said pattern mask in the range of 1 to 10 mm.

9. The light direction sensor of claim 4, wherein said Cartesian grid intentionally dims the light from some of the slits by alternatively skipping placement of slits in the Cartesian grid.

10. The light direction sensor of claim 4, wherein said slits are arranged such that the patterns they produce on said image sensor do not interfere with each other.

11. A method for determining the direction of a light source, comprising:

receiving a beam of light onto a patterned mask, wherein said patterned mask as a plurality of a slit segments;

diffusing the beam of light onto a image sensor; and

determining the direction of the light source.

12. The method of claim 11, wherein the determining step further comprising computing the direction of the light source based on geometry of similar triangles.

13. The method of claim 11, wherein the plurality of slits on said patterned mask are in a Cartesian grid.

14. The method of claim 13, wherein said Cartesian grid intentionally dims the light from some of the slits by alternatively skipping placement of some of the slits in the Cartesian grid.

15. The method of claim 11, wherein said slit are arranged such that the patterns they produce on said image sensor do not influence each other.