Hologram device and method for producing the same

• US 6,111,670 A
• Filed: 12/19/1997
• Issued: 08/29/2000
• Est. Priority Date: 12/20/1996
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kanda, Tomoyuki, Nishii, Katsuyoshi, Takada, Kenichiro, Matsumoto, Tooru, Hattori, Hidekazu
• Primary Examiner(s): Schuberg, Darren E.
• Application Number:
  US08/994,361
• Time in Patent Office: 984 Days
• Field of Search: 359/1, 359/15, 359/16, 359/28
• US Class Current: 359/15
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03H 1/0486 Improving or monitoring the quality of the record, e.g. by compensating distortions, aberrations
• CPC Class Codes: G03H 1/26 Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
• CPC Class Codes: G03H 2001/0473 Particular illumination angle between object or reference beams and hologram
• CPC Class Codes: G03H 2001/2236 Details of the viewing window
• CPC Class Codes: G03H 2001/306 Tiled identical sub-holograms
• CPC Class Codes: G03H 2210/20 2D object
• CPC Class Codes: G03H 2223/14 Diffuser, e.g. lens array, random phase mask
• CPC Class Codes: G03H 2250/12 Special arrangement of layers
• CPC Class Codes: G03H 2250/32 Antireflective layer
• CPC Class Codes: G03H 2250/39 Protective layer

Abstract

A hologram of an increased size using a single color laser, capable of executing a full color regeneration in a desired view angle and a method for producing the hologram. A plurality of photo-sensitive members are independently exposed to obtain respective holograms, which are connected by using an adhesive layer 80 constructing a connecting means, in order to obtain an integrated hologram expanded in two-dimensional direction. The holograms are obtained by an interference of a reference light 22 and an object light passed through a light diffusing body 24 in order to cause the light diffusing body 24 to be recorded on the photo-sensitive member. The size of the light diffusing body 24 is such that the spectral characteristic of the diffused light from the hologram can attain a desired efficiency at least over the entire wavelength range of the visible light.

Claims

1. A method for producing a hologram comprising:

generating a reference light;

generating an object light passed through a light diffusing body;

and exposing a photo-sensitive member by the reference light and the object and the object light so that interference occurs so that a diffraction grating corresponding to the light diffusing body is recorded on the photo-sensitive member;

the size of the light diffusing body being such that the hologram has a spectral characteristic of a diffused light from the hologram such that, in at least the wavelength range of visible light, a desired efficiency is obtained;

wherein the desired size of the light diffusing body which allows the hologram to have a spectral characteristic of a diffused light is of such a size that a difference m between the length S of a side of the light diffusing body and the length M of a side of the photo-sensitive member satisfies the following equation;

space="preserve" listing-type="equation">m=S-M=S.sub.1 +S.sub.2 ;

space="preserve" listing-type="equation">S.sub.1 ≧

L×

tan(sin.sup.-1 ((sin θ

.sub.1 -sin θ

c)×

(λ

.sub.0 /λ

.sub.c2)+sin θ

r)-M.sub.1, and

space="preserve" listing-type="equation">S.sub.2 ≧

L×

tan(sin.sup.-1 ((sin θ

.sub.1 -sin θ

c)×

(λ

.sub.0 /λ

.sub.c1)+sin θ

r)-M.sub.2,

Where;

θ

r is an incident angle of the reference light to the photo-sensitive member;

θ

₀ is an incident angle of the object light from the light diffusing body introduced into the photo-sensitive member;

θ

c is an incident angle of the regenerating light introduced into the hologram as produced;

θ

_I is an exit angle of the diffraction light from the hologram

λ

₀ is a wavelength of the laser beam during the recording;

λ

c is a wavelength in the diffracted direction θ

_i, where λ

c is in a range λ

_c1 to

λ

_c2 and λ

_c1 is 380 nm and λ

_c2 is 780 nm;

L is a distance between the light diffusing body and photo-sensitive member during a recording to the photo-sensitive member;

S₁ is a difference in length between the light diffusing body and the photo-sensitive member on the side adjacent the inlet side of the reference beam;

S₂ is a difference in length between the light diffusing body and the photo-sensitive member on the side opposite the inlet side of the reference beam;

M₁ is a distance between an end of the photo-sensitive member adjacent the inlet side of the reference light and a point A on one of the photo-sensitive member and the hologram where the reference light is introduced, and;

M₂ is a distance between an end of the photo-sensitive member opposite to the inlet side of the reference light and the point A.

2. A method according to claim 1, wherein a plurality of holograms on which the light diffusing body is recorded are integrally arranged in a two dimensional area.

3. A method according to claim 1, further comprising;

partially overlapping the holograms which are adjacent to each other; and

cutting the overlapped portions, so that the holograms are integrated.

4. A method for producing a hologram comprising:

generating a reference light;

generating an object light passed through a light diffusing body; and

exposing a photo-sensitive member by the reference light and the object light so that interference occurs so that a diffraction grating corresponding to the light diffusing body is recorded on the photo-sensitive member;

wherein the exposure of the photo-sensitive member is done by rotating, in a system for exposing the photo-sensitive member, the photo-sensitive member and the light diffusing body about an axis transverse to and passed through the center of the photo-sensitive member by the same angle in such a manner that the optical system for an exposure of the photo-sensitive member is kept horizontal.

5. A method according to claim 4, wherein the rotating movement of the photo-sensitive member and the light diffusing body is done independently about the each of three axes which are orthogonal to each other and which are transverse to and passed through the center of the photo-sensitive member.

6. A method according to claim 5, wherein a plurality of holograms on which the light diffusing body is recorded are integrally arranged in a two dimensional area.

7. A method according to claim 5, further comprising:

partially overlapping the holograms which are adjacent to each other; and

cutting the overlapped portions, so that the holograms are integrated.

8. A method according to claim 4, wherein an exposure of the photo-sensitive member is done in such a manner that an unnecessary part of at least the light diffusing body is made to be opaque.

9. A method according to claim 4, wherein a plurality of holograms on which the light diffusing body is recorded are integrally arranged in a two dimensional area.

10. A method according to claim 4, further comprising:

partially overlapping the holograms which are adjacent to each other; and

cutting the overlapped portions, so that the holograms are integrated.