Image capture with spatial light modulator and single-cell photosensor

• US 5,212,555 A
• Filed: 12/17/1991
• Issued: 05/18/1993
• Est. Priority Date: 12/17/1991
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Stoltz, Richard A.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Powell, Mark R.
• Application Number:
  US07/809,607
• Time in Patent Office: 518 Days
• Field of Search: 358/206, 358/225, 358/63, 358/55, 358/233, 358/199, 358/209
• US Class Current: 348/203
• CPC Class Codes: H04N 3/08 having a moving reflector

Abstract

An apparatus and method for capturing an image, using a spatial light modulator (SLM) 11 and a single-element sensor 15. The SLM 11 is an array of individually switchable pixel elements, which reflect light toward the sensor if switched to an "on" position. As each pixel element is switched on, light from that pixel element is directed to the sensor 15. For each pixel element, the sensor 15 generates a signal proportional to the light associated with that pixel element, the result being a series of signals representing at least one image frame. The process may be repeated for a number of image frames for generating moving pictures.

Claims

1. An optics unit for capturing an image, comprising:

a means for directing image-reflected light to a spatial light modulator;

a spatial light modulator (SLM) comprised of an array of reflective pixel elements, which are individually addressable and switchable, such that a series of pixel-reflected light beams are reflected from said SLM as different pixels are switched;

a control circuit for addressing and switching said SLM;

a means for focussing said pixel-reflected light to a photosensor; and

a photosensor for detecting a single pixel-reflected light beam and for generating an electrical signal proportional to the intensity of said pixel-reflected light.

2. The optics unit of claim 1, and further comprising a plurality of sensors, each for detecting a beam of pixel-reflected light from a different pixel element of said SLM.

3. The optics unit of claim 1, where said sensor is color-sensitive.

4. The optics unit of claim 1, and further comprising a plurality of color-sensitive sensors for detecting the same pixel-reflected beam.

5. The optics unit of claim 1, and further comprising an analog to digital converter for converting said electrical signal to a series of digital codes.

6. The optics unit of claim 1, and further comprising a capacitor circuit for transforming said electrical signal into an analog signal usable by conventional image generating equipment.

7. The optics unit of claim 1, and further comprising timing means for switching said SLM, such that a number of pixel elements representing an image frame are addressed in series.

8. The optics unit of claim 1, wherein said SLM is a deformable mirror device.

9. A method of using a spatial light modulator and at least one single-cell sensor to capture an image in the form of an electrical signal, comprising the steps of:

directing image-reflected light from an image to a spatial light modulator (SLM);

switching a pixel element of said SLM to an on position, such that said image-reflected light is reflected by said pixel element as a pixel-reflected beam;

focussing said pixel-reflected beam onto a single-cell photosensor;

detecting said pixel-reflected beam with said single-cell photosensor;

generating an electrical signal proportional to said pixel-reflected light, using the output of said sensor; and

repeating said switching and detecting steps for a series of said pixel elements until a number of said pixel elements, representing an image frame containing said image, have been switched.

10. The method of claim 9, and further comprising the step of timing said switching step so that said pixel elements of said image frame are switched in near real-time.

11. The method of claim 9, wherein said detecting step is performed with a number of color-sensitive sensors simultaneously.

12. The method of claim 9, and wherein said switching step is modified so that more than one additional pixel element is switched on at the same time to generate and number of pixel-reflected beams, and said detecting step is modified so that a sensor associated with each pixel-reflected beam detects that beam.

13. The method of claim 9, and further comprising the step of capturing a succession of image frames.

14. The method of claim 9, and further comprising the step of converting said electrical signal into a digital signal.

15. The method of claim 9, and further comprising the step of delivering said electrical signal to capacitor circuitry for generating a conventional analog image signal.

16. An image capturing system, comprising:

an optics unit for capturing an image having a means for directing image-reflected light to a spatial light modulator (SLM), a SLM comprised of an array of reflective pixel elements, which are individually addressable and switchable, such that a series of pixel-reflected light beams are reflected from said SLM as different pixels are switched, a means for focussing said pixel-reflected light to a photosensor, and a photosensor for detecting a single pixel-reflected light beam and for generating an electrical signal proportional to the intensity of said pixel-reflected light;

an analog to digital converter for converting said electrical signal to a digital signal; and

a processor for performing image processing operations on said digital signal.

17. The system of claim 16, wherein said spatial light modulator is a deformable mirror device.