METHOD FOR PRODUCING HOLOGRAM LENS, METHOD FOR PRODUCING HOLOGRAM COLOR FILTER, AND SPACE LIGHT MODULATING APPARATUSES USING THE HOLOGRAM LENS AND THE HOLOGRAM COLOR FILTER RESPECTIVELY

• US 20010049061A1
• Filed: 12/04/1998
• Published: 12/06/2001
• Est. Priority Date: 12/05/1997
• Status: Active Grant

• Current Assignee: Rakuten, Inc. (Rakuten Group, Inc.)
• Original Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Inventors: SHIMIZU, SHIGEO, NAKAGAKI, SHINTARO, IMAOKA, HIROFUMI
• Granted Patent: US 6,492,065 B2
• Time in Patent Office: Days
• US Class Current: 430/1
• CPC Class Codes: G02B 5/203 having holographic or diffractive elements diffraction gratings per se G02B5/18; holographic elements per se G02B5/32; generating the spectrum using diffraction elements G01J3/18
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses

Abstract

A thickness of each hologram lens for forming a hologram color filter is set so as to be smaller as the wavelength of light to be diffracted by each hologram lens is shorter. A thin plate glass layer is bonded to a surface of the hologram color filter such that it is in a firm contact therewith by adhesive agent and a sum of the thickness of the thin plate glass layer and thickness of the adhesive agent is smaller than the shortest focal length of the focal lengths in glass of a plurality of the hologram lenses. As a result, light diffracted and divided by the hologram color filter is focused on a picture element electrode of a corresponding color properly thereby eliminating deterioration of color reproduction due to mixing of colors. Further, upon production of the hologram color filter from hologram recording material, an influence of a fringe rotation is compensated.

Claims

1. A hologram color filter having two or more hologram lenses, wherein the thickness of each layer of the hologram lenses having two or more layers is smaller as the wavelength of light to be diffracted by each layer is shorter.

2. A hologram color filter according to

claim 1

, wherein the thickness of each of the hologram lenses having two or more layers accurately corresponds to a ratio of the wavelength of light to be diffracted by each layer.

3. A space light modulating apparatus comprising:

the hologram color filter according to

claim 1

; and

a space light modulating element for modulating light diffracted by the hologram color filter.

4. A space light modulating apparatus comprising:

the hologram color filter according to

claim 2

; and

a space light modulating element for modulating light diffracted by the hologram color filter.

5. A space light modulating apparatus comprising:

a hologram color filter formed by overlaying a plurality of different hologram lenses relating to the three primary colors or carrying out multiple exposures on a single layer hologram light sensitive film by the plurality of the hologram lenses, the hologram color filter diffracting incident white reading light to a plurality of light beams having each different wavelength and focusing each thereof onto a picture element electrode of each corresponding color;

a thin plate glass layer provided in a firm contact with reading light emission side of the hologram color filter; and

a space light modulating element for modulating light diffracted by the hologram color filter,

the space light modulating apparatus being so constructed that the thickness of the thin plate glass layer is smaller than the shortest focal length of the focal lengths in glass of each of the plurality of the hologram lenses.

6. A space light modulating apparatus according to

claim 5

, wherein the thin plate glass layer is bonded to a reading light emission side surface of the hologram color filter via adhesive agent and a sum of the thickness of the adhesive agent and thickness of the thin plate glass layer is smaller than the shortest focal length of the focal lengths in glass of each of the plurality of the hologram lenses.

7. A method for producing a hologram color filter comprising the steps of:

forming a fringe pattern on a hologram recording material;

creating a one-layer hologram lens by heat-development of the hologram recording material;

providing a further hologram recording material on the one-layer hologram lens; and

repeating the above procedure so as to create a multiple layer hologram lens,

wherein the fringe pattern to be formed on the hologram recording material is formed at a recording angle for compensating for a fringe rotation such that light having a desired wavelength is emitted in a desired direction.

8. A method for producing a hologram color filter according to

claim 7

, wherein the desired direction is a normal direction of the hologram color filter.

9. A space light modulating apparatus comprising:

a hologram color filter produced according to the production method of

claim 7

; and

a space light modulating element for modulating light diffracted by the hologram color filter.

10. A space light modulating apparatus comprising:

a hologram color filter produced according to the production method of

claim 8

; and

a space light modulating element for modulating light diffracted by the hologram color filter.