Holographic exposure system for computer generated holograms

• US 4,960,311 A
• Filed: 08/31/1989
• Issued: 10/02/1990
• Est. Priority Date: 08/31/1989
• Status: Expired due to Term

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Moss, Gaylord E., Wreede, John E.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): RYAN, JAY
• Application Number:
  US07/401,394
• Time in Patent Office: 397 Days
• Field of Search: 350/3.6, 350/3.66, 350/3.67, 350/3.69, 350/3.81, 350/3.83
• US Class Current: 359/9
• CPC Class Codes: G03H 1/20 Copying holograms by holographic , i.e. optical means
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A computer generated diffraction grating which exhibits multiple order scattering noise is illuminated by a point source to generate a first wavefront which is intersected with a second wavefront to form a desired interference pattern in a recording medium. The point source is moved relative to the recording medium during exposure in order to reduce multiple order scattering noise.

Claims

1. A system for exposing a recording medium with a computer generated diffraction grating which exhibits multiple order scattering noise when illuminated comprising:

a point source of illumination positioned to direct light at the diffraction grating for exposing the recording medium;

means for relatively moving the point source during the exposure to reduce the multiple order scattering noise;

means for interacting with the point source to form a desired interference pattern; and

means for varying the wavelength of the point source to compensate for any variation in formation of fringe spacing in the recorded interference pattern.

2. A system for exposing a hologram comprising:

a recording medium;

a computer generated diffraction means for providing a first wavefront when illuminated, said diffraction grating being positioned next to the recording medium;

means for directing a point source of illumination at the diffraction grating and for relatively moving said point source during the exposure of the recording medium;

means for providing a second wavefront to the recording medium whereby the respective first and second wavefronts interact to form the desired interference pattern in the recording medium; and

means for varying the wavelength of the point source to compensate for any variations in formation of fringe spacing in the recorded interference pattern.

3. The invention of claim 2 wherein the wavelength of the point source is varied during exposure of the recording medium.

4. A method of exposing a hologram comprising of the recording medium

providing a recording medium;

providing a computer generated diffraction grating providing a first wavefront when illuminated;

illuminating the computer generated diffraction grating with a point source of illumination to direct the first wavefront at the recording medium;

forming a second wavefront from a reference object;

directing the second wavefront at the recording medium to interact with the first wavefront to form the desired interference pattern in the recording medium; and

relatively moving the point source of illumination during exposure of the recording medium, wherein the wavelength of the point source is varied to compensate for any variations in formation of the fringe spacing in the recorded interference pattern.

5. The method of claim 4 wherein the wavelength of the point source is varied during exposure of the recording mediums.