LIQUID CRYSTAL OPTICAL PROCESSOR

• US 3,744,879 A
• Filed: 10/26/1971
• Issued: 07/10/1973
• Est. Priority Date: 10/26/1971
• Status: Expired due to Term

• Current Assignee: Terry D. Beard, William P. Bleha Jr
• Original Assignee: Terry D. Beard, William P. Bleha Jr
• Inventors: Bleha, William P. Jr., Beard, Terry D.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Stern, Ronald J.
• Application Number:
  US05/192,406
• Time in Patent Office: 623 Days
• Field of Search: 350/3.5,162SF,16LC
• US Class Current: 349/17
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G02F 1/135 Liquid crystal cells structurally associated with a photoconducting or a ferro-electric layer, the properties of which can be optically or electrically varied G02F1/133348 takes precedence

Abstract

The optical processor employs a photoconductor-activated liquid crystal as a spatial filter to control transmissivity of coherent light through the processor. The liquid crystal filter pattern determines the pattern input to Fourier transform and can optionally also define the transmissivity of a Fourier processing filter. This permits near real time transform.

Claims

2. The optical processor of claim 1 wherein said filter is sensitive to illumination by light having a wavelength in a second range, and said second illumination means illuminates said filter with said image with light having a wavelength in said second range, and said collimated source of illumination for directing light along said axis has a wavelength in a first range substantially outside of said second range.

3. The optical processor of claim 2 wherein said liquid crystal filter comprises first and second spaced filter cover plates, each carrying a substantially transparent electric conductive layer, a photoconductor between said filter plate and adjacent one of said cover plates, and a liquid crystal between said photoconductor and the other of said cover plates, so that application of voltage between said electrically conductive layers applies an electric field across said photoconductor and said liquid crystal.

4. The optical processor of claim 3 wherein said photoconductor in said liquid crystal filter has reduced resistivity when illuminated by light of wavelength in said second range so that a portion of the liquid crystal adjacent the illuminated photoconductor has a higher electric field applied thereto.

5. The optical processor of claim 4 wherein said liquid crystal is a nematic liquid crystal.

6. The optical processor of claim 5 wherein a direct current electric field with a superimposed alternating current electric field is applied across said electrically conductive layer.

7. The optical processor of claim 4 wherein said liquid crystal is a liquid crystal of mixed nematic and cholesteric liquid crystal materials.

8. The optical processor of claim 7 wherein a source of direct current electrical potential is applied to said electrically conductive layers.

9. The optical processor of claim 1 further including a spatial filter at said transform plane, a retransform lens downstream from said transform plane and means for observing the retransformed image along the axis downstream from said retransform lens, said spatial filter at said transform plane being a second liquid crystal filter.

10. The optical processor of claim 9 further including second illumination means for illuminating a second image and projection means for projecting said second illuminated image onto said spatial filter at said transform plane, separately from said laser source of illumination so that said second liquid filter can be addressed by said second illuminated image.

11. The optical processor of claim 10 wherein said second liquid crystal filter comprises first and second spaced filter cover plates, each carrying a substantially transparent electric conductive layer, a photoconductor between said cover plates and adjacent one of said cover plates, and a liquid crystal between said photoconductor and the other of said cover plates so that application of voltage between said electrically conductive layers applies an electric field across said photoconductor and said liquid crystal.

12. The optical processor of claim 11 wherein said photoconductor in said second liquid crystal filter has reduced resistivity when illuminated by light of wavelength to which it is sensitive so that a portion of the liquid crystal adjacent the illuminated photoconductor has a higher electric field applied thereto.

13. The optical processor of claim 12 wherein said liquid crystal in said second liquid crystal filter is a nematic liquid crystal.

14. The optical processor of claim 13 wherein a direct current electric field with a superimposed alternating current electric field is applied across said electrically conductive layer.

15. The optical processor of claim 11 wherein said liquid crystal in said second liquid crystal filter is a liquid crystal of mixed nematic and cholesteric liquid crystal materials.

16. The optical processor of claim 15 wherein a source of direct current electrical potential is applied to said electrically conductive layers.