Dynamic optical filtration

• US 6,864,473 B2
• Filed: 12/07/2000
• Issued: 03/08/2005
• Est. Priority Date: 12/07/2000
• Status: Expired due to Fees

• Current Assignee: United States Administrator of National Aeronautics and Space Administration
• Original Assignee: United States Administrator of National Aeronautics and Space Administration
• Inventors: Lu, Edward T., Chretien, Jean-Loup
• Primary Examiner(s): Luu, Thanh X.
• Application Number:
  US09/988,855
• Publication Number:
  US 20020071185A1
• Time in Patent Office: 1,552 Days
• Field of Search: 250/201.1, 250/204, 250/206, 250/229, 349/13, 349/14, 351/44, 351/45, 396/276, 359/738
• US Class Current: 250/201.1
• CPC Class Codes: G02B 5/20 Filters polarising elements G02B5/30
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/75 by influencing optical camera components
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation

Abstract

A dynamic optical filtration system and method effectively blocks bright light sources without impairing view of the remainder of the scene. A sensor measures light intensity and position so that selected cells of a shading matrix may interrupt the view of the bright light source by a receptor. A beamsplitter may be used so that the sensor may be located away from the receptor. The shading matrix may also be replaced by a digital micromirror device, which selectively sends image data to the receptor.

Claims

1. A method for adjusting the opacity of a matrix comprising a plurality of cells, the method comprising:

receiving incident light intended for a receptor;

receiving the incident light into a beamsplitter;

refracting part of the incident light to a sensor;

identifying a portion of the incident light that exceeds a predetermined threshold intensity;

identifying a bright light source in the incident light;

identifying a direction of the bright light source;

identifying a direction of sight of the receptor;

determining an angle from the direction of the bright light source and the direction of sight of the receptor;

defining an active zone equivalent to a first predetermined range of angles associated with the direction of the bright light source and the direction of sight of the receptor;

defining a passive zone equivalent to a second predetermined range of angles associated with the direction of the bright light source and the direction of sight of the receptor;

determining whether the angle falls within the active zone or the passive zone; and

adjusting the opacity of at least one cell of the matrix based on the identified portion, the identified bright light source, and the determination as to whether the angle falls within the active zone or the passive zone.

2. The method of claim 1, identifying a portion of the incident light that exceeds a predetermined threshold intensity further comprising:

associating a first intensity value to the incident light; and

comparing the first intensity value to the predetermined threshold intensity.

3. A system comprising:

a light deflector to redirect incident light of an image being received by a dynamically moving receptor;

a first sensor to receive the redirected incident light, to track the intensity of the redirected incident light, and to track the direction of the image;

a second sensor to track a direction of sight of the receptor, wherein the direction of sight is a function of the dynamic movement of the receptor;

a matrix disposed between the light deflector and the receptor, the matrix comprising a plurality of cells, wherein the opacity of each of the cells may selectively be adjusted; and

a controller coupled to the matrix, wherein the controller;

receives the intensity of the redirected incident light information and the direction of the image information from the first sensor;

receives the direction of sight information from the second sensor;

calculates an angle formed by the direction of the image information and the direction of sight information;

defines an active zone based on a predetermined range of values of the angle;

defines a passive zone based on a predetermined range of values of the angle;

determines if the angle corresponds to the active zone or the passive zone; and

adjusts the opacity of one or more cells of the matrix based upon the intensity of the redirected incident light information and whether the angle corresponds to the active zone or the passive zone.

4. The system of claim 3, wherein the matrix comprises a plurality of two-dimensional transmissive liquid crystal display cells.

5. The system of claim 3, wherein the first sensor comprises a plurality of photoreceptor cells.

6. The system of claim 3, wherein the controller comprises a processor-based system including a software program.

7. The system of claim 3, wherein the deflector comprises a beamsplitter.

8. The system of claim 7, wherein the beamsplitter passes about 90% of the incident light while deflecting about 10% of the incident light to the first sensor.

9. The system of claim 7, wherein the beamsplitter passes about 60% of the incident light while deflecting about 40% of the incident light to the first sensor.

10. The system of claim 7, wherein the beamsplitter passes about 50% of the incident light while deflecting about 50% of the incident light to the first sensor.

11. The system of claim 3, wherein the first sensor comprises a charge-coupled device located inside a camera body.

12. The system of claim 11, wherein the controller further includes parameter adjustment controls.

13. The system of claim 3, further comprising an adjustable lens which receives the incident light and focuses the incident light on the matrix.

14. A method of operating a general purpose data processor of known type to enable the data processor to execute an object program, wherein the object program stores a predetermined first range and a predetermined second range, wherein the object program uses inputs from a first sensor and a second sensor, wherein the object program controls a shading matrix comprising a plurality of cells, the method comprising the steps of:

receiving light intensity information and direction of light information from the first sensor;

receiving direction of sight information from the second sensor;

measuring a third angle from the direction of light information and the direction of sight information;

defining an active zone based on the predetermined first range;

defining a passive zone based on the predetermined second range;

determining whether the third angle is within the active or passive zone;

comparing the light intensity information to a predetermined threshold intensity value; and

adjusting the opacity of one or more cells of the shading matrix based on the light intensity information as compared to the predetermined threshold intensity value and whether the third angle is within the active or passive zone.

15. A method for dynamic optical filtration of a matrix, said matrix comprising a plurality of cells, said method comprising:

identifying a source of bright light in incident light, said incident light to be received by a receptor wherein a direction of sight is associated with said receptor;

determining an angle between said source of bright light and said direction of sight;

defining an active zone range and passive zone range for said angle;

determining whether said angle is in said active zone or said passive zone; and

adjusting the opacity of at least one cell in the matrix based whether said angle is within said active zone or said passive zone.