LARGE ARRAY SYNTHESIZING

• US 3,591,252 A
• Filed: 10/21/1968
• Issued: 07/06/1971
• Est. Priority Date: 10/21/1968
• Status: Expired due to Term

• Current Assignee: Lu Sun
• Original Assignee: Lu Sun
• Inventors: LU SUN
• Application Number:
  US04/769,103
• Time in Patent Office: 988 Days
• US Class Current: 359/9
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03B 27/44 for multiple copying of the same original at the same time G03B27/34, G03B27/53 take precedence
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G06V 10/895 the filter being related to phase processing, e.g. phase-only filters
• CPC Class Codes: Y10S 359/90 Methods

Abstract

An array of similar images may be synthesized by holographic reconstruction techniques. To produce a large array of similar images, a hologram is constructed that contains the spatial frequency spectrum of the desired array. This frequency spectrum may be generated by usual holographic procedures wherein an object wave and a reference wave are made to interfere on an energy sensitive surface. Since the information contained on the hologram represents an array of points which synthesizes the spatial frequency spectrum, the hologram must be produced by sequentially exposing the energy sensitive surface to a series of interference patterns. To control the amplitude and phase distribution of each point representing the spatial frequency spectrum, both the exposure time and phase displacement between the interfering beams are uniquely determined from a mathematical model of the spatial frequency spectrum.

Claims

1. A method of producing a relatively large array of images on a display surface by synthesizing the spatial frequency spectrum of said large array with a relatively small array of pOint sources, comprising the steps of:

determining said synthesized spatial frequency spectrum of said large array of images in accordance with the relationship delta (v-qR lambda /T) and delta (u-pR lambda /T) are delta functions at u pR lambda /T, v qR lambda /T, where T the periodicity of the periodic array, lambda the wavelength, p and q are integers, and R is the distance between the surface and the plane of the spatial frequency spectrum said synthesized spatial frequency spectrum comprising a relatively small array of point sources with respect to said large array of images, each of said point sources having a different spatial position, amplitude and phase angle with respect to the remaining points;

recording said relatively small array of point sources on an energy sensitive surface;

reconstructing an image of said relatively small array of point sources; and

forming a diffraction pattern of said reconstructed image, thereby producing said relatively large array of similar images on said display surface.

2. The method of producing a relatively large array of similar images as set forth in claim 1 wherein the step of recording said relatively small array of point sources on an energy sensitive surface comprises the steps of:

generating a first energy wave;

splitting said first energy wave into a reference wave and an object wave;

directing said reference wave to impinge upon said energy sensitive surface;

directing said object wave through a phase cell to control the phase angle between said object wave and said reference wave;

sequentially controlling said phase cell to produce different phase controlled object waves corresponding to the phase angle of respective point sources of said relatively small array of point sources;

directing respective phase controlled object waves to impinge upon a mask having an aperture therein;

controlling the spatial position of said aperture to sequentially produce each point of said relatively small array of point sources; and

sequentially controlling the exposure of said energy sensitive surface to respective phase angle controlled and spatial position controlled object waves to produce a series of interference patterns in said energy sensitive surface, said interference patterns respectively having amplitudes corresponding to respective points of said relatively small array of point sources.

3. The method as set forth in claim 2 wherein said energy sensitive surface comprises a photographic emulsion and wherein said energy wave comprises a beam of monochromatic coherent light.

4. The method as set forth in claim 1 wherein the step of reconstructing an image of said relatively small array of point sources comprises:

generating a beam of monochromatic coherent light; and

positioning said energy sensitive surface having said interference patterns corresponding to said relatively small array of point sources recorded thereon in said beam to reconstruct an image of said array of point sources thereby producing said synthesized spatial frequency spectrum.

5. Apparatus for producing a relatively large array of similar images by synthesizing the spatial frequency spectrum of said large array with a relatively small array of point sources, comprising in combination:

a source of monochromatic coherent light;

a hologram positioned within said light, said hologram comprising a series of interference patterns, each interference pattern recording the relative phase angle, amplitude and spatial position of a discrete point of said relatively small array of point sources that synthesizes the spatial frequency spectrum of said relatively large array of images, said source of coherent light being operative to reconstruct an image of said relatively small array of point sources; and

means for generating the diffraction pattern of said Image of said relatively small array of point sources to thereby produce said relatively large array of similar images.

6. Apparatus for producing a relatively large array of images as set forth in claim 5 wherein said means for generating the diffraction pattern of said relatively small array of point sources includes a semiconductor wafer coated with a photoresist emulsion.

7. Apparatus for synthesizing the diffraction pattern of a relatively large array of similar images on an energy sensitive surface comprising:

means for producing a first coherent energy wave;

means for producing a second energy wave having coherence with said first wave and interfering therewith at said energy sensitive surface;

means for varying the exposure time of the energy sensitive surface to the interference pattern of said energy waves to record the amplitude of respective points of said diffraction pattern;

means for varying the phase difference between said energy waves at the energy sensitive surface to record the phase angle of respective points of said diffraction pattern; and

means for sequentially positioning one of said energy waves at different locations to sequentially record on said energy sensitive surface each point of said diffraction pattern in a different spatial location.