Adaptive optical filter

• US 8,531,753 B1
• Filed: 05/09/2011
• Issued: 09/10/2013
• Est. Priority Date: 05/09/2011
• Status: Active Grant

• Current Assignee: TRIAD National Security, LLC
• Original Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Inventors: Whittemore, Stephen Richard
• Primary Examiner(s): CHOI, WILLIAM C
• Application Number:
  US13/103,846
• Time in Patent Office: 855 Days
• Field of Search: 359237-239, 359/245, 359/246
• US Class Current: 359/245
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02F 2203/12 spatial light modulator

Abstract

Imaging systems include a detector and a spatial light modulator (SLM) that is coupled so as to control image intensity at the detector based on predetermined detector limits. By iteratively adjusting SLM element values, image intensity at one or all detector elements or portions of an imaging detector can be controlled to be within limits. The SLM can be secured to the detector at a spacing such that the SLM is effectively at an image focal plane. In some applications, the SLM can be adjusted to impart visible or hidden watermarks to images or to reduce image intensity at one or a selected set of detector elements so as to reduce detector blooming.

Claims

1. An imaging system, comprising:

a lens situated to receive a light flux from an object and form a real image of the object;

an imaging detector situated so as to receive the real image of the object from the lens, wherein the imaging detector is a detector array that includes a plurality of detector elements;

a lens aperture situated to establish a lens f-number; and

a spatial light modulator situated proximate the lens so as to receive and transmit the light flux associated with the real image to the detector array and to selectively attenuate at least some portion of the received flux, wherein the spatial light modulator includes a plurality of light modulator elements, and the imaging detector and the spatial light modulator are situated so that one or more of the detector elements correspond to one or more of the light modulator elements, wherein the spatial light modulator is secured to the lens or the imaging detector and the plurality of light modulator elements define a modulator plane that is parallel to a detector plane.

2. The imaging system of claim 1, wherein the light modulator elements are situated so as to align with one or more corresponding detector elements.

3. The imaging system of claim 1, wherein the spatial light modulator is a liquid crystal spatial light modulator.

4. The imaging system of claim 1, wherein the imaging detector is a charge-coupled device array.

5. An imaging system, comprising:

a lens situated to receive a light flux from an object and form a real image of the object;

an imaging detector situated so as to receive the real image of the object from the lens, wherein the imaging detector is a detector array that includes a plurality of detector elements;

a lens aperture situated to establish a lens f-number;

a spatial light modulator situated proximate the lens so as to receive and transmit the light flux associated with the real image to the detector array and to selectively attenuate at least some portion of the received flux, wherein the spatial light modulator includes a plurality of light modulator elements; and

a spatial light modulator controller that is configured to establish a transmissivity of the light modulator elements based on a light intensity received by at least a portion of the imaging detector and to establish a transmissivity of at least one modulator element based on a light intensity at one or more detector elements, wherein the spatial light modulator controller is configured to adjust the transmissivity of the at least one light modulator element of the spatial light modulator iteratively based on a detected light intensity at one or more corresponding detector elements.

6. The imaging system of claim 5, wherein the spatial light modulator controller is coupled to the lens aperture and configured to selectively establish an f-number or a spatial light modulator transmission based on the light intensity received by the imaging detector.

7. The imaging system of claim 5, wherein the spatial light modulator controller is configured to estimate a center of an illuminated area on the imaging detector, and establish a transmission of at least one light modulator associated with the estimated center.

8. The imaging system of claim 5, wherein the spatial light modulator controller is configured to reduce the transmissivity of the at least one modulator element of the spatial light modulator based on the magnitude of a detected light intensity.

9. The imaging system of claim 5, wherein the at least one light modulator element of the spatial light modulator is configured to reduce a received intensity at least one detector element so as to be less than a predetermined limit.

10. The imaging system of claim 5, wherein the plurality of light modulator elements are situated so as to align with one or more corresponding detector elements.

11. The imaging system of claim 5, wherein the spatial light modulator is a liquid crystal spatial light modulator.

12. The imaging system of claim 5, wherein the imaging detector is a charge-coupled device array.

13. An imaging system, comprising:

a lens situated to receive a light flux from an object and form a real image of the object;

an imaging detector situated so as to receive the real image of the object from the lens, wherein the imaging detector is a detector array that includes a plurality of detector elements;

a lens aperture situated to establish a lens f-number;

a spatial light modulator situated proximate the lens so as to receive and transmit the light flux associated with the real image to the detector array and to selectively attenuate at least some portion of the received flux, wherein the spatial light modulator includes a plurality of light modulator elements; and

a spatial light modulator controller configured to establish a transmissivity of the light modulator elements based on a light intensity received by at least a portion of the imaging detector and to establish a transmissivity of at least one modulator element based on a light intensity at one or more detector elements, wherein the spatial light modulator controller is configured to adjust the transmissivity of the at least one light modulator element based on a detected light intensity and a color component associated with the detected light intensity.

14. An imaging system, comprising:

a lens situated to receive a light flux from an object and form a real image of the object;

an imaging detector situated so as to receive the real image of the object from the lens, wherein the imaging detector is a detector array that includes a plurality of detector elements;

a lens aperture situated to establish a lens f-number;

a spatial light modulator situated proximate the lens so as to receive and transmit the light flux associated with the real image to the detector array and to selectively attenuate at least some portion of the received flux, wherein the spatial light modulator includes a plurality of light modulator elements; and

a spatial light modulator controller configured to establish a transmissivity of the light modulator elements based on a light intensity received by at least a portion of the imaging detector, wherein the spatial light modulator is secured to the lens or the imaging detector and the plurality of light modulator elements define a modulator plane that is parallel to a detector plane.