Optical-digital hologram recording

• US 4,701,006 A
• Filed: 02/20/1985
• Issued: 10/20/1987
• Est. Priority Date: 02/20/1985
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Stanford University
• Inventors: Perlmutter, Robert J.
• Primary Examiner(s): Arnold, Bruce Y.
• Application Number:
  US06/703,521
• Time in Patent Office: 972 Days
• Field of Search: 350/3.66, 350/3.6, 350/3.67
• US Class Current: 359/9
• CPC Class Codes: G03H 1/0248 Volume holograms
• CPC Class Codes: G03H 1/08 Synthesising holograms, i.e. holograms synthesized from objects or objects from hologramsusing electric digital computers G06F; G06T
• CPC Class Codes: G03H 1/0891 Processes or apparatus adapted to convert digital holographic data into a hologram G03H1/2294 takes precedence
• CPC Class Codes: G03H 2001/0415 for recording reflection holograms
• CPC Class Codes: G03H 2001/0478 Serial printer, i.e. point oriented processing
• CPC Class Codes: G03H 2001/0482 Interference based printer
• CPC Class Codes: G03H 2210/454 into planes
• CPC Class Codes: G03H 2225/33 Complex modulation
• CPC Class Codes: G03H 2240/13 Amplitude and phase complex modulation
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A hologram is formed of an object by calculating a two dimensional complex field distribution for a diffraction pattern of the object, and then modulating a first coherent light beam with amplitude and phase values of the two-dimensional complex field distribution as the first coherent light beam is scanned across a recording medium. A second reference coherent light beam is scanned across the recording medium and intersects the first modulated coherent light beam in the recording medium as the two beams are scanned. A reflection hologram is synthesized in the recording medium by directing the two beams from opposite sides of the film recording medium.

Claims

1. A method of recording a hologram in a recording medium comprising the steps of

calculating samples of a two-dimensional complex field distribution for a diffraction pattern of a three-dimensional object based on a computer model of the object,

providing a recording medium,

providing a first reference coherent light source and

providing a second object coherent light source through use of a laser-visible light source and optics to split light from said laser source into two beams, and expander and collimator means to expand and collimate the two light beams,

modulating a light beam from said second object coherent light source in response to amplitude and phase values of said two-dimensinal complex field distribution samples, and

scanning said recording medium with a reference light beam from said first reference coherent light source and with a modulated object beam from said second object coherent light source by providing opaque plates with apertures therein and moving said apertures, said light beams intersecting in said recording medium as said beams are scanned.

2. The method as defined by claim 1 wherein the frequencies of said first and second beams and the angle of inclination of said reference beam with respect to the surface of said recording medium are established by said calculated two dimensional complex field distribution.

3. The method as defined by claim 2 wherein said object light beam and said reference light beam are directed onto said film recording medium from opposite sides of said film recording medium.

4. The method as defined by claim 1 wherein said diffraction pattern is a Fresnel diffraction pattern.

5. Means for recording a hologram in a medium comprising

means for calculating a two-dimensional complex field distribution for a diffraction pattern of an image based on a computer model of the object,

means for providing a first reference coherent light source and means for providing a second object coherent light source comprising a visible light laser source, a beam splitter to obtain an object beam and a reference beam, and expander and collimator means for expanding and collimating the reference beam and the object beam,

means for amplitude and phase modulating a light beam from said second object coherent light source in response to amplitude and phase values of said two-dimensional complex field distribution, and

means for directing a reference light beam from said first reference coherent light source and a modulated light beam from said second object coherent light source onto a recording medium including first and second opaque plates with apertures therein, said light beams scanning said recording medium and intersecting in said recording medium.

6. Means as defined by claim 5 wherein said means for directing directs said reference light beam and said modulated light beam from opposite sides of said film recording medium.

7. Means as defined by claim 5 wherein said diffraction pattern is a Fresnel diffraction pattern.

8. Means as defined by claim 5 wherein said apertures are moved by electronically controlled electro-optic crystals.