Chromatic aberration correction for display systems

• US 5,889,625 A
• Filed: 05/21/1997
• Issued: 03/30/1999
• Est. Priority Date: 05/21/1997
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Chen, Chungte W., Yaffe, Roger E., Bentley, Kris E.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US08/861,143
• Time in Patent Office: 678 Days
• Field of Search: 359/637, 359/634, 348/806, 348/807
• US Class Current: 359/637
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: H04N 9/28 Arrangements for convergence or focusing

Abstract

A full color display optical system with chromatic aberration correction. The system includes a wide spectral band image source such as a cathode ray tube or Ferroelectric liquid crystal array, a field sequential Red-Green-Blue shutter, and an optical module for projection. The optical module corrects longitudinal chromatic aberration and higher order monochromatic and chromatic aberrations. Lateral chromatic aberration and chromatic distortion are compensated electronically by the color sequential shutter and the image source with a pre-distorted image.

Claims

1. A color optical display system with chromatic aberration correction, comprising:

a wide spectral band image source for generating an image for display;

a color sequential shutter for dividing an image frame period into three sub-frame intervals, a first interval for passing a first color image component comprising the image to be projected, a second interval for passing a second color image component comprising the image to be projected, and a third sub-frame interval for passing a third color image component comprising the image to be projected, said image source and said color sequential shutter comprising an apparatus for lateral chromatic aberration and chromatic distortion compensation; and

a projection optical module adapted to provide correction for longitudinal chromatic aberration, and wherein said projection optical module does not provide correction for lateral chromatic aberration or chromatic distortion.

2. The system of claim 1 wherein the projection optical module includes an achromatic doublet comprising a positive lens fabricated from a crown glass, and a negative lens fabricated from a flint glass.

3. The system of claim 1 wherein said wide spectral image source comprises first, second and third distortion correction functions corresponding to said first, second and third colors for electronically compensating said lateral chromatic aberration and chromatic distortion.

4. The system of claim 1 wherein said wide spectral image source comprises a cathode ray tube.

5. The system of claim 1 wherein said wide spectral image source comprises a ferroelectric liquid crystal array.

6. The system of claim 1 wherein said first color is red, said second color is green, and said third color is blue.

7. The system of claim 1 wherein said system is a helmet mounted display, said image source, said color sequential shutter and said projection optical module mounted on a helmet, said helmet mounted display further comprising a visor for reflecting images passed through said projection optical module toward a helmet wearer'"'"'s eye.

8. A color optical display system with chromatic aberration correction, comprising:

a wide spectral band image source for generating an image for display in response to electronic image signals;

a color sequential shutter responsive to electronic shutter control signals for dividing an image frame period into three sub-frame intervals, a first interval for passing a first color image component comprising the image to be projected, a second interval for passing a second color image component comprising the image to be projected, and a third sub-frame interval for passing a third color image component comprising the image to be projected;

first, second and third distortion correction functions corresponding to said first, second and third colors for electronically compensating lateral chromatic aberration and chromatic distortion of said display system;

a display controller and image generator for generating said electronic image signals and said shutter control signals, said display controller and image generator for mapping first, second and third color components of an image to be displayed into a pre-distorted image, wherein said pre-distortion compensates for lateral chromatic aberration and chromatic distortion of said display system; and

a projection optical module adapted to provide correction for longitudinal chromatic aberration, and wherein said projection optical module does not provide correction for lateral chromatic aberration or chromatic distortion.

9. The system of claim 8 wherein the projection optical module includes an achromatic doublet comprising a positive lens fabricated from a crown glass, and a negative lens fabricated from a flint glass.

10. The system of claim 8 wherein said wide spectral image source comprises a cathode ray tube.

11. The system of claim 8 wherein said wide spectral image source comprises a ferroelectric liquid crystal array.

12. The system of claim 8 wherein said first color is red, said second color is green, and said third color is blue.

13. The system of claim 8 wherein said system is a helmet mounted display, said image source, said color sequential shutter and said projection optical module mounted on a helmet, said helmet mounted display further comprising a visor for reflecting images passed through said projection optical module toward a helmet wearer'"'"'s eye.