Computer generated hologram optical element

• US 20070008597A1
• Filed: 07/05/2006
• Published: 01/11/2007
• Est. Priority Date: 07/06/2005
• Status: Abandoned Application

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Watanabe, Masachika, Kitamura, Mitsuru, Eto, Koji
• Application Number:
  US11/481,263
• Publication Number:
  US 20070008597A1
• Time in Patent Office: Days
• US Class Current: 359/3
• CPC Class Codes: G03H 1/02 Details of features involved during the holographic process; Replication of holograms without interference recording
• CPC Class Codes: G03H 1/0244 Surface relief holograms replicating hologram without interference recording G03H1/0276
• CPC Class Codes: G03H 1/0252 Laminate comprising a hologram layer
• CPC Class Codes: G03H 1/0486 Improving or monitoring the quality of the record, e.g. by compensating distortions, aberrations
• 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 2001/2234 Transmission reconstruction
• CPC Class Codes: G03H 2250/36 Conform enhancement layer
• CPC Class Codes: G03H 2250/37 Enclosing the photosensitive material
• CPC Class Codes: G03H 2250/39 Protective layer

Abstract

A main object of the present invention is to provide a computer-generated hologram optical element with little decline of the image converting function even when a pollutant such as oil and water is adhered to the surface. To achieve the object, the present invention provides a computer-generated hologram optical element comprising: a transmission type Fourier transform hologram comprising a substrate, and an image converting layer formed on the substrate and having a function as a Fourier transform lens; a diffraction function layer disposed on the image converting layer of the transmission type Fourier transform hologram and having a certain refractive index difference with respect to the image converting layer; and a protection layer formed on the diffraction function layer.

Claims

1. A computer-generated hologram optical element comprising:

a transmission type Fourier transform hologram comprising a substrate, and an image converting layer formed on the substrate and having a function as a Fourier transform lens;

a diffraction function layer disposed on the image converting layer of the transmission type Fourier transform hologram and having a certain refractive index difference with respect to the image converting layer; and

a protection layer formed on the diffraction function layer.

2. The computer-generated hologram optical element according to claim 1, wherein the diffraction function layer is made of air.

3. The computer-generated hologram optical element according to claim 1, wherein the diffraction function layer and the protection layer are formed integrally with a same resin.

4. The computer-generated hologram optical element according to claim 1, wherein the refractive index difference between the diffraction function layer and the image converting layer is in a range of 0.75×

(λ

₀/D)×

(N−

1)/N to 1.25×

(λ

₀/D)×

(N−

1)/N,

(in which the λ

₀ is a reference wavelength, the D is a maximum depth of a minute concavo-convex shape formed on a surface of the image converting layer, and the N is number of steps of the minute concavo-convex shape formed on the surface of the image converting layer).

5. The computer-generated hologram optical element according to claim 2, wherein the refractive index difference between the diffraction function layer and the image converting layer is in a range of 0.75×

(λ

₀/D)×

(N−

1)/N to 1.25×

(λ

₀/D)×

(N−

1)/N,

(in which the λ

₀ is a reference wavelength, the D is a maximum depth of a minute concavo-convex shape formed on a surface of the image converting layer, and the N is number of steps of the minute concavo-convex shape formed on the surface of the image converting layer).

6. The computer-generated hologram optical element according to claim 3, wherein the refractive index difference between the diffraction function layer and the image converting layer is in a range of 0.75×

(λ

₀/D)×

(N−

1)/N to 1.25×

(λ

₀/D)×

(N−

1)/N,

(in which the λ

₀ is a reference wavelength, the D is a maximum depth of a minute concavo-convex shape formed on a surface of the image converting layer, and the N is number of steps of the minute concavo-convex shape formed on the surface of the image converting layer).

7. The computer-generated hologram optical element according to claim 1, wherein printing is applied to the protection layer.

8. The computer-generated hologram optical element according to claim 2, wherein printing is applied to the protection layer.

9. The computer-generated hologram optical element according to claim 3, wherein printing is applied to the protection layer.

10. The computer-generated hologram optical element according to claim 1, wherein the optical element comprises an anti-reflection layer.

11. The computer-generated hologram optical element according to claim 2, wherein the optical element comprises an anti-reflection layer.

13. The computer-generated hologram optical element according to claim 3, wherein the optical element comprises an anti-reflection layer.