Method and apparatus for holographic recording

Patent metadata

Field	Value
Publication number	US-12468257-B2
Application number	US-202218062965-A
Country	US
Kind code	B2
Filing date	Dec 7, 2022
Priority date	Dec 1, 2022
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

Abstract

The present invention relates to a method and apparatus for holographic recording based on holographic printing technology, and more specifically, to a method and apparatus for holographic recording, in which the hologram is recorded after the deviation in diffraction efficiency for each hogel is pre-compensated for by varying the intensity (luminance) of the object beam for each hogel during the hologram recording in response to a deviation in diffraction efficiency (reconstruction efficiency) for each hogel of a holographic recording surface that occurs when the hologram is reproduced. Accordingly, the reproduction imbalance of a near-eye display (NED) using a holographic optical element (HOE) is resolved by controlling the diffraction efficiency uniform on the entire holographic recording surface when the hologram is reproduced.

First claim

What is claimed is:

1 . A method of hologram recording, in which holograms are recorded in a method of tiling an entire recording surface of a holographic recording medium by interfering with an object beam and a reference beam for each divided hogel on the holographic recording medium divided in units of hogels and recording the holograms using holographic printing technology,
analyzing, by a control computer, deviations in diffraction efficiency for each hogel according to a recording angle for each hogel when holograms are recorded on the holographic recording medium for each hogel, wherein the recording angle refers to a crossing angle formed by the object beam and the reference beam when the holograms are recorded by interference of the object beam and the reference beam on the holographic recording medium; pre-compensating, by the control computer, the deviations in diffraction efficiency by varying an intensity of the object beam for each hogel according to the deviations in diffraction efficiency; and recording, by an object beam optical unit, holograms by varying the intensity of the object beam for each hogel in accordance with the pre-compensated intensity and allowing the varied object beam to be incident on the holographic recording medium.

2 . The method of hologram recording of claim 1 , wherein, in the pre-compensating the deviations in diffraction efficiency, the intensity of the object beam is increased so that brightness increases from a central portion to an edge of the holographic recording medium, or decreased so that the brightness decreases from the edge to the central portion of the holographic recording medium.

3 . The method of hologram recording of claim 1 , wherein, in the pre-compensating the deviations in diffraction efficiency, a computer-generated hologram (CGH) fringe pattern is generated for modulation of the object beam.

4 . The method of hologram recording of claim 3 , wherein, in the pre-compensating the deviations in diffraction efficiency, the CGH fringe pattern is generated using the Rayleigh-Sommerfeld diffraction integral (RSD).

5 . The method of hologram recording of claim 4 , wherein, in the pre-compensating the deviations in diffraction efficiency, the generated CGH fringe pattern is divided into n×m pieces (here, n and m are natural numbers) corresponding to the number of hogels, and the object beam is modulated using each of the divided pieces of the CGH fringe pattern.

6 . An apparatus for hologram recording, in which holograms are recorded in a method of tiling an entire recording surface of a holographic recording medium by interfering with an object beam and a reference beam for each divided hogel on the holographic recording medium divided in units of hogels and recording the holograms using holographic printing technology, the apparatus comprising:
a laser configured to output a laser beam; a beam splitter configured to split the laser beam into an object beam and a reference beam; a control computer configured to generate a computer-generated hologram (CGH) fringe pattern; an object beam optical unit configured to transmit the object beam to the holographic recording medium and record the object beam; a reference beam optical unit configured to allow the reference beam to be incident on the holographic recording medium,
wherein the control computer analyzes deviations in diffraction efficiency for each hogel according to a recording angle for each hogel when holograms are recorded on the holographic recording medium for each hogel, and
wherein the recording angle refers to a crossing angle formed by the object beam and the reference beam when the holograms are recorded by interference of the object beam and the reference beam on the holographic recording medium; and
pre-compensates the deviations by varying an intensity of the object beam for each hogel according to the deviations in diffraction efficiency, wherein the object beam optical unit comprises:
a spatial light modulator configured to modulate the incident object beam using the CGH fringe pattern provided by the control computer, and vary the intensity of the object beam for each hogel in accordance with the pre-compensated intensity, and
a condensing lens configured to condense the object beam modulated by the spatial light modulator onto the holographic recording medium.

7 . The apparatus for hologram recording of claim 6 , wherein the control computer increases the intensity of the object beam so that brightness increases from a central portion to an edge of the holographic recording medium, or decreases the intensity of the object beam so that the brightness decreases from the edge to the central portion of the holographic recording medium.

8 . The apparatus for hologram recording of claim 6 , wherein the control computer generates the CGH fringe pattern using the Rayleigh-Sommerfeld diffraction integral (RSD) and then divides the generated CGH fringe pattern into n×m pieces horizontally and vertically (here, n and m are natural numbers) corresponding to the number of hogels to provide the divided pieces of the CGH fringe pattern to the spatial light modulator.

Assignees

• Univ Kwangwoon Ind Acad Collab

Inventors

• Lee Seung Hyun
• Hwang Lee Hwan
• Kwon Soon Chul
• Kim Jungho
• Gentet Philippe

Classifications

• G03H2222/12

  Single or narrow bandwidth source, e.g. laser, light emitting diode [LED] · CPC title

• G03H1/0402

  Recording geometries or arrangements (G03H1/0443, G03H1/0476, G03H1/16 take precedence) · CPC title

• G02B2027/0109

  comprising details concerning the making of holograms · CPC title

• G02B2027/0174

  holographic · CPC title

• G02B27/0172

  characterised by optical features · CPC title