JPH10340038A - Hologram duplicating method and volume hologram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a hologram image display which is lighter than an original plate by irradiating a duplicated hologram at a specific assumed lighting angle and making duplication illumination light at such an angle of incidence that a fringe having such an assumed slant angle that an observation can be made at a specific assumed observation center angle can be duplicated and recorded. SOLUTION: The duplicated volume hologram 4 is irradiated with illumination light 7 at an angle θ of incidence (assumed lighting angle) and observed from a direction centering on an angle γ (assumed observation center angle). For the purpose, a fringe 8 having at least a slant angle Sg should be duplicated in the volume hologram 4. When duplication is performed with illumination light having an angle of incidence meeting conditions of the duplication of the fringe 8, a fringe having at least the specific slant angle Sg among many fringes having various slant angles formed with light scattered by a body in many directions at the time of recording is duplicated as a fringe 8 having the same slant angle Sg finally in a postprocessed hologram 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram duplication method and a volume hologram, and more particularly to diffraction of unnecessary light (such as zero-order light) when a volume hologram recording an image of a scattering object is duplicated by a hologram duplication method. The present invention relates to a hologram duplication method and a volume hologram capable of displaying a brighter image than an original by limiting a viewing range (viewing angle range) in which a recorded image can be observed to a desired range.

[0002]

2. Description of the Related Art It is well known that a hologram reproducible under white illumination light is recorded by causing scattered light from a scattering object and reference light to interfere in a volume hologram photosensitive material. In addition, another volume hologram photosensitive material is superimposed on a reflection type or transmission type volume hologram, a laser beam is made incident from the other photosensitive material side or original plate side, and the incident light and the diffracted light diffracted by the volume hologram are separated. A method (hologram duplication method) of duplicating the same hologram as the original volume hologram by causing interference in the other light-sensitive material is also well known.

[0003]

However, conventionally,
When duplicating a volume hologram recorded with a scattering object by the hologram duplication method, the angle of incidence of the laser beam for duplication should be selected near the angle of incidence of the reference beam when recording the original, or no special consideration was given Was. Therefore, in the duplicated hologram, unnecessary interference fringes based on the specular reflection light (0th order light) from the scattering object are still recorded, or the visual field in which the recorded image can be observed is as wide as that of the original. Unnecessary fringes (interference fringes) caused unnecessary diffracted light, and as a result, a very bright display could not be obtained.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to reproduce a volume hologram in which an image of a scattering object is recorded by a hologram duplication method based on regular reflection. By providing a hologram duplication method and volume hologram capable of restricting diffraction of unnecessary light due to zero-order light and the like, and restricting a viewing range in which a recorded image can be observed to a desired range and displaying an image brighter than the original. is there.

[0005]

According to the hologram duplication method of the present invention which achieves the above object, when a volume hologram recording an image of a scattering object is duplicated by a hologram duplication method,
In replicated replicated holograms, and illuminating a predetermined assumed illumination angle theta, incident replication illumination light at an incident angle I ₁ of the fringe of the assumed slant angle S _g as can be observed in a predetermined estimated observation central angle φ can be replicated records It is a method characterized by making it.

In this case, it is desirable that the incident angle I ₁ satisfies the following equation (6). I ₁ = sin ⁻¹ << n ₁ / n ₀ × sin <± cos ⁻¹ [λ ₁ / (ν ₀ λ ₀ ) × cos ｛sin ⁻¹ (n ₀ / n ₁ × sin I ₀ ) − ｛sin ⁻¹ (N ₀ / n ₁ × sin θ) + sin ⁻¹ (n ₀ / n ₁ × sin φ)｝ / 2−τ ₀ ｝] + {sin ⁻¹ (n ₀ / n ₁ × sin φ) + sin ⁻¹ (n ₀ / n ₁ × sin θ)｝ / 2 −τ ₁ 〉>> (6) where I ₀ : original recording reference light incident angle λ ₀ : original recording wavelength ν ₀ : original photosensitive material contraction rate τ ₀ : original fringe slant Angle change λ ₁ : Duplicate wavelength τ ₁ : Duplicate fringe slant angle change n ₀ : Refractive index outside photosensitive material n ₁ : Refractive index inside photosensitive material

[0007] Further, a first image recording an image of the first scattering object.
Volume hologram and an image of the second scattering object
When replicating an original obtained by superimposing the volume hologram on the same volume hologram photosensitive material, the duplicated hologram is illuminated at a predetermined assumed illumination angle θ with respect to the hologram image of the first scattering object. Illuminating a fringe of a first assumed slant angle S _g1 that can be observed at a _first assumed observation center angle φ ₁ and a hologram image of a second scattering object at a predetermined assumed illumination angle θ; First assumed observation center angle φ ₁
Fringe having an assumed slant angle S _g2 that can be observed at a _second predetermined assumed observation center angle φ ₂ different from the above, or an incident angle I at which three or more different fringes can be similarly recorded.
_{In step 1} , duplicate illumination light can be incident.

In addition, a first volume hologram recording an image of a first scattering object at a first wavelength and a second volume hologram recording an image of a second scattering object at a second wavelength are superimposed. When the original master is duplicated in the same volume hologram light-sensitive material, a third duplicated hologram in which the first wavelength and the wavelength ratio have a fixed relationship with respect to the hologram image of the first scattering object is obtained. the illumination light is irradiated at a predetermined assumed illumination angle theta, and a fringe of assumed slant angle S _g as can be observed in supposed observation center angle phi, the second wavelength and the wavelength ratio to the hologram image of the second scattering objects Are in the same constant relationship
Incident angle illumination light irradiated at a predetermined assumed illumination angle theta, fringe same assumed slant angle S _g as can be observed in the same supposed observation center angle phi, or that three or more fringe different similarly be replicated records it can be made to be incident replication illumination light I _1.

According to another hologram duplication method of the present invention, when a volume hologram in which an image of a scattering object is recorded is duplicated by a two-stage hologram duplication method, the hologram surface is duplicated in the first stage. Of an assumed slant angle S _gx that can be illuminated with a predetermined assumed illumination angle component θ _x in one of two directions orthogonal to each other along the direction and can be observed with a predetermined assumed observation center angle component φ _x in that direction. Duplicate illumination light is incident at an incident angle I _1x at which fringes can be duplicated and recorded, and in a duplicate hologram duplicated in the second stage, a predetermined assumed illumination angle component in the other of the two orthogonal directions along the hologram surface Illumination is performed at θ _y , and duplicate illumination light is incident at an incident angle I _1y at which a fringe having an assumed slant angle S _gy that can be observed at a predetermined assumed observation center angle component φ _y in the other direction can be copied. It is a method characterized by making it.

[0010] The volume hologram of the present invention, there is provided a volume hologram that records the image of a scattering object, illuminated with a predetermined illumination angle theta, the slant angle S _g as can be observed at a predetermined observation center angle φ the slant angle S _g at the center of the fringe
Only the fringes of the slant angle within a predetermined width ΔS before and after are recorded.

Another volume hologram of the present invention is a volume hologram in which an image of a scattered object is recorded. The volume hologram is illuminated at a predetermined illumination angle θ and can be observed at a predetermined observation center angle φ _{1. g1} and fringe slant angle of the slant angle S _g1 within a predetermined range [Delta] S ₁ before and after the center of the fringe, said illuminated with a predetermined illumination angle theta, can be observed another of different predetermined observation center angle phi ₂ another fringe of another different slant angle slant angle of the slant angle S _g2 within the width [Delta] S ₂ given before and after the center of the fringe of S _g2 like, or only three or more fringe different in the same manner is recorded It is characterized by having.

Still another volume hologram of the present invention is a volume hologram recording an image of a scattering object,
The illumination light of the first wavelength irradiated at a predetermined illumination angle theta, the first slant angle S _g as can be observed at a predetermined observation center angle φ
And fringe slant angle of the slant angle S _g within the predetermined range [Delta] S ₁ before and after the center of the fringe of the illumination light of the second wavelength is irradiated at the same predetermined illumination angle theta, the same predetermined observation center angle φ A predetermined width ΔS around the slant angle S _g around the second fringe having the same slant angle S _g as can be observed at
₂ is characterized in that only the fringes of the slant angle in ₂ , or similarly three or more different fringes are recorded.

In these cases, it is desirable that the hologram image is recorded so as to be reproduced near the hologram surface.

In the present invention, the copied hologram is illuminated at a predetermined assumed illumination angle θ, and the assumed slant angle S _g can be observed at a predetermined assumed observation center angle φ.
Fringe the since the incident replication illumination light at an incident angle I ₁ that can replicate records, limit the diffraction of the unnecessary light, 0 order light or the like based on specular reflection, and a viewing zone that can observe the recorded image in a desired range The hologram image is displayed brighter than the original.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of a hologram duplication method and a volume hologram according to the present invention and some embodiments will be described below with reference to the drawings. It is considered that a scattering object is recorded as a volume hologram (Denishook hologram), and that is used as an original, and another recording material is superimposed on the original to duplicate the hologram.

First, as shown in FIG. 1, an illuminating light 2 is applied to an object O, and a scattered light 3 from the illuminating light 2 and a reference light 2 serving as the illuminating light interfere with each other in a volume hologram photosensitive material 1 such as a photopolymer. Record the hologram master. At this time, the object O
May be performed not by the 0th-order light 2 transmitted through the volume hologram photosensitive material 1 but by a branched light different from the light 2. The incident angle of the reference light 2 at the time of recording the original is I ₀ , and its wavelength is λ ₀ .

The contraction rate of the volume hologram photosensitive material 1 due to post-processing of the original recorded in this manner is ν ₀ , and the slant angle of the fringe (interference fringe) recorded therein (the normal to the fringe surface is the volume hologram sensitivity). Angle with respect to the normal to one surface)
Is assumed to be τ ₀ .

As shown in FIG. 2, another volume hologram sensitive material 4 is closely adhered to the original 1 'recorded and post-processed as shown in FIG. Illumination light 5 having a wavelength λ ₁ is incident from the side at an incident angle I ₁ , and a diffracted light 6 diffracted from the original 1 ′ interferes in the volume hologram photosensitive material 4 to perform hologram replication. In addition,
When the original 1 ′ is a transmission type, the illumination light 5 is incident from the original 1 ′ side.

The shrinkage ratio of the volume hologram photosensitive material 4 due to the post-processing of the hologram thus duplicated is ν ₁ , and the change in the slant angle of the fringe recorded therein is τ ₁ .

The average refractive index of the volume hologram photosensitive materials 1 and 4 is n ₁ , and the external refractive index is n ₀ .

Now, as shown in FIG. 3, the volume hologram 4 'duplicated in this manner is irradiated with illumination light 7 at an incident angle θ.
(Assumed illumination angle), and observation is performed from a direction centered on the angle φ (assumed observation center angle). Such a in order to allow observation, fringe 8 of at least slant angle S _g is must be replicated in a volume hologram 4 '.

[0022] Hereinafter, such a fringe 8 seeks condition of the angle of incidence I ₁ of the illumination light 5 during replication to be replicated, but will be summarized before that, the symbols below.

I ₀ : Original recording reference light incident angle λ ₀ : Original recording wavelength ν ₀ : Original photosensitive material shrinkage ratio τ ₀ : Original fringe slant angle change I ₁ : Duplicate illumination light incident angle λ ₁ : Duplicate wavelength ν ₁ : Duplicated photosensitive material contraction rate τ ₁ : Duplicate fringe slant angle change n ₀ : Refractive index outside photosensitive material n ₁ : Refractive index inside photosensitive material θ: Assumed illumination angle φ: Assumed observation center angle S _g : Assumed slant angle For simplicity, When "'" is added to the angle in photosensitive materials 1 and 4,
The slant angle S _g is given by: S _g = (θ ′ + φ ′) / 2 = {sin ⁻¹ (n ₀ / n ₁ × sin θ) + sin ⁻¹ (n ₀ / n ₁ × sin φ)} 1) must be satisfied.

[0024] Now, the original plate 1 'hologram 4, which was copied or post-processing the fringe of the slant angle S _g of the previous post-processing at the time of recording'
When copying as a fringe with the same slant angle S _g during copying, the pitch (distance between fringes) P _t0 at the time of copying (FIG. 2) the fringe with the slant angle S _g during recording in the master 1 ′ is P _t0 = ν ₀ n ₀ λ ₀ / {2n ₁ cos (I ₀ ′ −S _g −τ ₀ )} (2)

Further, the pitch P _t1 (slant angle S _{g-tau 1)} at the time of replication of the fringe slant angle S _g of the hologram 4 'in duplicating-aftertreatment (FIG. 2), P _t1 = n ₀ λ ₁ / {2n ₁ cos (I ₁ ′ −S _g + τ ₁ )} (3)

The refractive indices of both photosensitive materials 1 and 4 are equal to n ₁ , and the fringe to be duplicated of the original 1 ′ and the fringe to be duplicated and recorded in the photosensitive material 4 are duplicated while satisfying the Bragg condition. From the condition, P _t0 = P _t1 (4) From the above (1) to (4), the incident angle I ₁ of the illumination light 5 at the time of duplication.
Ν ₀ n ₀ λ ₀ / {2n ₁ cos (I ₀ ′ −S _g −τ ₀ )} = n ₀ λ ₁ / {2n ₁ cos (I ₁ ′ −S _g + τ ₁ )} ·· _{· (5) ν 0 λ 0} / cos (I 0 '-S g -τ 0) = λ 1 / cos (I 1' -S g + τ 1) cos (I 1 '-S g + τ 1) = λ 1 / (Ν ₀ λ ₀ ) × cos (I ₀ ′ −S _g −τ ₀ ) I ₁ ′ = ± cos ⁻¹ ｛λ ₁ / (ν ₀ λ ₀ ) × cos (I ₀ ′ −S _g −τ ₀₎ )｝ + S _g −τ ₁ sin ⁻¹ (n ₀ / n ₁ × sin I ₁ ) = S _g −τ ₁ ± cos ⁻¹ [λ ₁ / (ν ₀ λ ₀ ) × cos ｛sin ⁻¹ (n ₀ / _{n 1 × sinI 0) -S g} -τ 0}] I 1 = sin -1 "n 1 / n 0 × sin <± cos -1 [λ 1 / (ν 0 λ 0) × cos {sin -1 ( n ₀ / n ₁ × sin I ₀ ) − {sin ⁻¹ (n ₀ / n ₁ × sin θ) + sin ⁻¹ (n ₀ / n ₁ × sin φ)} / 2 −τ ₀ }] + {sin ⁻¹ (n _{0 / n 1 × sinφ) +} sin -1 (n 0 / n 1 × sinθ)} / 2 -τ 1>"= f (I 0, _{, Φ, ν 0, λ 1} / λ 0, n 1 / n 0, τ 0, τ 1) ··· (6) i.e., when replicated in the illumination light 5 incident angle I ₁ satisfying the expression (6), In the post-processed hologram 4 ', a number of fringes having various slant angles formed by the light 3 scattered in multiple directions from the object O during recording (FIG. 1)
A fringe having at least a specific slant angle S _g will eventually be replicated as a fringe 8 having the same slant angle S _g . In the above study, the slant angle changes τ ₀ and τ ₁ have been considered, but can be ignored in an actual volume hologram photosensitive material.

As apparent from the above calculation, P
I ₁ satisfying _t0 = P _t1 exists two. In equation (5), the cosine variable 両 sin ^-1 (n ₀ / n ₁ × sin
I ₀ ) −S _g −τ ₀ } and {sin ⁻¹ (n ₀ / n ₁ · sin I)
₁₎ -S _g + tau or _1} is the same sign, it is distinguished by whether the different signs, the I ₁ in the case of the same sign I ₁ ^A, the I ₁ in the case of different signs is defined as I ₁ ^B , Around expected slant angle S _g +
Attention is paid to a change in pitch at ΔS.

In the case of I ₁ ^A , as shown schematically in FIG. 4A, the directions of change of P _t0 and P _t1 due to the increase and decrease of ΔS coincide. On the other hand, in the case of I ₁ ^B , as shown schematically in FIG. 4B, the directions of change of P _t0 and P _t1 due to the increase and decrease of ΔS do not match. This means that the slant angle change ΔS for a fringe that satisfies the Bragg condition of a fringe whose incident light diffracted while satisfying the Bragg condition at the slant angle S _g is diffracted at, for example, half its efficiency is reproduced at I ₁ ^A. Is larger than that in the case of duplication by I ₁ ^B. That is, better to duplicate an original 1 'at an incident angle I ₁ ^A can replicate fringe wide slant angle range than replicate in I ₁ ^B. From this, when replicating at the incident angle I ₁ ^A , a replicated hologram having a wide viewing area (viewing angle range) around the assumed slant angle S _g is obtained, and the incident angle I
When replicating in ₁ ^B would duplicate hologram having a narrow viewing zone about the assumed slant angle S _g (viewing angle range) is obtained.

Specific numerical examples will be given. I ₀ = 45 °,
λ ₀ = 514.5 nm, ν ₀ = 0.99, λ ₁ = 51
4.5 nm, n ₀ = 1, n ₁ = 1.52, θ = 40 °,
If φ = 0 ° and τ ₀ = τ ₁ = 0, S _g = 12.51
° (0.218 rad), and I ₁ ^A = 40.74 °
(0.71 rad), I ₁ ^B = −0.62 ° (−0.0
1 rad). FIG. 5 shows the relationship between the fringe pitch and slant angle during recording in the original and the pitch and slant angle in the duplicated and post-processed hologram.

As described above, according to the hologram duplication method of the present invention, when a volume hologram recording an image of a scattering object is duplicated by the hologram duplication method, the duplicated hologram is illuminated at a predetermined assumed illumination angle θ. In order to enable observation at a predetermined assumed observation center angle φ, the incident angle I ₁ of the duplicate illumination light when the duplicate hologram is duplicated from the volume hologram of the original is determined based on the above equation (6). It is. Alternatively, when the volume hologram recording the image of the scattering object is copied by the hologram duplication method, the copied hologram is illuminated at a predetermined assumed illumination angle θ and can be observed at a predetermined assumed observation center angle φ. Incident angle I at which fringe with assumed slant angle S _g can be duplicated and recorded
_{In step 1} , duplicate illumination light is incident. By using such a hologram duplication method, diffraction of unnecessary light due to 0th-order light or the like based on regular reflection is limited, and a viewing range in which a recorded image can be observed is limited to a desired range, so that an image brighter than the original can be obtained. A hologram that can be displayed can be duplicated.

FIG. 6 shows a volume hologram recording an image of a conventional scattered object or a volume hologram copied therefrom by a conventional hologram duplication method (FIG. 6A) and an image of a scattered object obtained by the hologram duplication method of the present invention. FIG. 3 is a diagram qualitatively comparing a recorded volume hologram with a replicated volume hologram (FIG. 2B), assuming both reflection-type volume holograms. In the case of a conventional volume hologram or a volume hologram 10 duplicated therefrom, an image O 'of a scattering object O is recorded. In addition to the diffracted light 11 emitted, the diffracted light 12 emitted in other scattering directions is also diffracted. In addition, the diffracted light 13 corresponding to the regular reflection light from the scattering object O at the time of recording is diffracted in a direction other than the observation direction. Since such fringes for diffracting the diffracted lights 12 and 13 are multiplexed and recorded on the volume hologram 10, the refractive index modulation of the fringe for diffracting the diffracted light 11 contributing to the actual observation becomes smaller, and the diffracted light is correspondingly reduced. 11 is weak. On the other hand, in the case of the volume hologram 4 'copied from the volume hologram in which the image O' of the scattering object O is recorded by the hologram duplication method of the present invention, the fringe for diffracting the diffracted light 11 within the limited viewing zone α is used. Only the diffracted light 12 emitted in the other direction is recorded, and the scattering object O at the time of recording is recorded.
Since the fringe for diffracting the diffracted light 13 corresponding to the specular reflection light from the light source is removed and not recorded at the time of duplication, the refractive index modulation of the fringe for diffracting the diffracted light 11 contributing to actual observation increases. Accordingly, the intensity of the diffracted light 11 is increased, and an object image O ′ brighter than the original can be observed. That is, in the present invention, at the time of duplication, the incident angle I ₁ of the duplicate illumination light is selected so as to limit the viewing zone,
The intensity of the diffracted light 11 in the divided viewing area α whose viewing area is restricted is increased, and a brighter object image O ′ can be observed.

Therefore, for example, when the hologram duplication method of the present invention is applied to manufacture a hologram diffusion plate by recording a hologram using the light diffusion plate as the scattering object O, the hologram duplication method according to the present invention is applied to the regular reflection light from the light diffusion plate during recording. Since the corresponding fringe is removed and not recorded at the time of duplication, in a liquid crystal display device or the like incorporating such a hologram diffusion plate, no diffracted light corresponding to the regular reflection component of the illumination light is emitted. Therefore, a hologram capable of bright display can be obtained by sorting light diffracted in the regular reflection direction in the past into diffracted light directed to a direction related to observation, for example, from an irradiation angle of 30 ° to an observation angle of 0 ° (from the normal). A diffusion plate can be obtained.

In the above discussion, the angle of incidence of the duplicated illumination light is selected so as to limit the viewing zone in a one-dimensional direction, for example, the x direction, at the time of duplication, but y is orthogonal to the direction. The viewing area is not limited in the direction (assuming that the plane of the hologram is parallel to the xy plane), and in that direction, not only the diffracted light emitted in the predetermined observation direction but also the other scattering directions Diffracted light is also diffracted. In addition, diffracted light corresponding to regular reflection light from a scattering object at the time of recording is also diffracted in directions other than the observation direction. In the y direction, the amount of diffracted light that contributes to actual observation becomes weaker.

Then, the same duplication method as described above is applied to the y direction, and the incident angle of the duplicate illumination light is adjusted so as to limit the viewing zone in any two directions perpendicular to the hologram plane. select. This method will be described on the assumption that a reflection hologram is used. As shown in FIG. 7A, first, the volume hologram photosensitive material 1 is arranged in front of the object O and the illumination light 2
And scattered light from the object O and the volume hologram photosensitive material 1
The first hologram master 1 ′ is recorded by causing interference in the inside.
Here, it is assumed that the volume hologram photosensitive material 1 is arranged in parallel to the xy plane, and the component (x direction component) of the incident angle of the illumination light 2 projected on the xz plane is I _0x , yz plane The component (y-direction component) projected to is _defined as I _0y .

Next, as shown in FIG.
And to record as (a), superimposed at a slight distance or close contact with another volume hologram photosensitive material 4 ₁ to the first hologram master 1 'workup, the volume hologram photosensitive material 4 ₁
From the side, the x-direction component incidence angle I _0x and the y-direction component incidence angle I _1y
In is incident illumination light 5 _first wavelength lambda _1, the first hologram master 1 diffracted light and the volume hologram photosensitive material 4 diffracted from '
The second hologram is duplicated by causing interference in ₁ . At this time, the y direction component incident angle I _1y is represented by θ _y as an assumed illumination angle component in the y direction and φ as an assumed observation center angle component in the y direction.
_{When y} is assumed, illumination is performed at an assumed illumination angle component θ _y in the y direction, and an incident angle at which a fringe of an assumed slant angle S _gy that can be observed with an assumed observation center angle component φ _y in the y direction can be duplicated and recorded. That is, the angle satisfies the expression (6).

Next, as shown in FIG.
Recorded way of (b), superimposed at a slight distance or close contact with another volume hologram photosensitive material 4 ₂ in the second hologram master 4 ₁ 'workup, the volume hologram photosensitive material 4
_{From the second} side, the x-direction component incident angle I _1x , the y-direction component incident angle I
It is incident illumination light 5 _second wavelength lambda ₁ in _1y, performing a second hologram replication and diffracted light diffracted by the interference in the volume hologram photosensitive material 4 ₂ from the second hologram master 4 ₁ '. At this time, when the assumed illumination angle component in the x direction is θ _x and the assumed observation center angle component in the x direction is φ _x , the assumed illumination angle component in the x direction is the x direction component incident angle I _1x. illuminated by theta _x, the incident angle of the fringe of the assumed slant angle S _gx as can be observed in the x-direction of the supposed observation center angle component phi _x can duplicate recording is an angle that satisfies the above equation (6).

Thus, in the first stage duplication,
While maintaining the x-direction component incident angle of the illumination light 5 ₁ the same as the first illumination light 2 during hologram master 1 'recording x-direction component I _0x, angle satisfying the expression (6) and the y-direction component incident angle I _1y
To, in the replication of the second stage, while maintaining the y-direction component incident angle of the illumination light 5 ₂ the same as the second illumination light 5 ₁ during hologram master 4 ₁ 'replication y-direction component incident angle I _1y, That x
By setting the direction component incident angle to an angle I _1x that satisfies the expression (6), only fringes that diffract diffracted light within the restricted viewing zone in both the x and y directions are recorded, and other directions are recorded. The fringes that diffract the diffracted light that exits and the diffracted light that corresponds to the specularly reflected light from the scattering object O during recording are removed during both duplications and are not recorded, diffracting the diffracted light that contributes to actual observation. The refractive index modulation of the fringe to be made increases accordingly, and the intensity of the diffracted light increases accordingly. Therefore, when illumination is performed from the direction of θ _x in the component of the x direction and θ _y in the component of the _y direction, the observation center angle is φ _x in the component of the x direction and φ _x in the component of the _y direction. , In the two-dimensional limited viewing area in the y direction, an object image brighter than the original can be observed. Note that FIG.
The step of (b) and the step of FIG. 7C may be performed in reverse.

The volume hologram duplicated by the hologram duplication method of the present invention as described above is a volume hologram recording an image of a scattering object, illuminated at a predetermined illumination angle θ, and set at a predetermined observation center angle φ. only the fringe slant angle of the slant angle in S _g before and after the predetermined width ΔS around the fringe slant angle S _g as can be observed in which are recorded. Such a volume hologram is observed only from a direction within a predetermined viewing zone α centered on the observation center angle φ, and is transparent when observed from other directions. Therefore, in the present invention, various images can be synthesized by freely controlling the viewing zone. FIG. 8 is a view showing one example of the same. According to the present invention, for example, a normal printed matter is formed under the volume hologram 20 in which the viewing zone is set in the narrow direction 23 using the above-mentioned duplicated illumination light incident angle I ₁ ^B. Underlying patterns 21 are superimposed on each other, and the viewing direction 23 of the volume hologram 20 is selected so that the underlying pattern 21 is not observed. With this setting, when the superimposed body is illuminated with the illumination light 22, only the ground pattern 21 can be observed when viewed from the front direction 24, and the object recorded on the volume hologram 20 can be observed when viewed from the direction 23. Base pattern 21
And the object image recorded on the volume hologram 20 can be separately recognized.

FIG. 9 shows a first volume hologram 25 in which the viewing area is set to a specific range α ₁ in _one volume hologram 25.
And a second fringe recording a second image which partially overlaps the viewing zone α ₁ and is set in a viewing zone α ₂ in another direction range. duplicate records in the method of the invention that follows, when illuminating the volume holograms 25 in the illumination light 22, when viewed from the direction 26 in the viewing area alpha ₁ looks first hologram image is different in the viewing zone alpha ₂ When viewed from the direction 27, the second hologram image can be seen, and the viewing zones α ₁ and α
_When viewed from the direction 28 in the range where ₂ overlaps, the first and second hologram images are observed and visible. That is, the hologram image that can be observed is switched by changing the viewing direction. Of course, three or more hologram images can be recorded with different viewing zones.

Such an observation image switching hologram 25
Is produced by the method of the present invention, the first object image is converted to a wavelength λ.
₀ , recording on the first volume hologram at the original recording reference light incident angle I ₀₁ . At this time, based on the equation (6), the duplicate illumination light incident angle is I ₁ , the assumed illumination angle is θ, and the assumed observation center angle is φ.
₁ determines the master recording reference beam angle of incidence I ₀₁ so that (the angle of the center of the viewing zone alpha _1). Further, the second object image is recorded on the second volume hologram at the same wavelength λ ₀ and the original recording reference light incident angle I ₀₂ . At this time, based on the above equation (6), the incident angle of the duplicated illumination light is the same as I ₁ as the first volume hologram, the assumed illumination angle is the same θ as the first volume hologram, and the assumed observation center angle is φ _2. determining the original recording reference beam angle of incidence I ₀₂ so that (the angle of the center of the viewing zone alpha _2). Thereafter, the first volume hologram and the second volume hologram are superimposed to form an original. By duplicating the original using illumination light having an incident angle I ₁ , the first fringe and the second fringe having the assumed observation center angles φ ₁ and φ ₂ are multiplex-recorded in one volume hologram 25. You.

The observation image switching hologram 25 shown in FIG. 9 can be used as the volume hologram 20 shown in FIG. Further, as the first object image and the second object image recorded on the observation image switching hologram 25, one can be a character or a symbol such as a logo, and the other can be a subject such as an object.

Next, a method for producing a multicolor recording Lippmann hologram by the method of the present invention will be described. As shown in FIG. 10, the B (blue) light scattering unit 31 and the R (red) light scattering unit 3
A multicolor recording Lippmann hologram of the object 30 composed of 2 is considered. First, as shown in FIG. 10A, a B volume hologram photosensitive material 33 is arranged above an object 30, and illumination light 34 having a wavelength λ _0B in the B wavelength band is incident on the object 30 at an incident angle I.
_{At 0} , the light is incident on the B volume hologram photosensitive material 33, and the transmitted light is reflected by the light scattered by the B light scattering portion 31 of the object 30 and the incident light 3
4 is made to interfere with a B volume hologram sensitive material 33 to record a B volume hologram, and as shown in FIG. 10B, an R volume hologram sensitive material 35 is superimposed thereon, and the wavelength in the R wavelength band is The illumination light 36 of λ _0R is irradiated with R at the same incident angle I ₀ as before.
The light is made incident from the side of the volume hologram photosensitive material 35, and the transmitted light is reflected by the R light scattering portion 32 of the object 30 and the incident light 36.
Are made to interfere with each other by an R volume hologram photosensitive material 35 to record an R volume hologram, and the both 33 and 35 are post-processed, and a superimposed body thereof is used as an original plate 37.

Next, as shown in FIG. 10C, another volume hologram light-sensitive material 3 sensitive to both the B and R wavelength regions is located at the position where the object 30 was located at the time of recording below the original plate 37.
8 is arranged in parallel with the master 37, and the wavelength λ _1B in the B wavelength band is set.
And the duplicate illumination light 39 which is superimposed on the light of the wavelength λ _1R in the R wavelength band or separately incident on the original 37 at an incident angle I _1.
, The image 30 ′ of the object 30 is reproduced in the vicinity of the surface of the volume hologram sensitive material 38, and the original 37 is copied to the volume hologram sensitive material 38. The hologram replicated and recorded in the volume hologram photosensitive material 38 is a Lippmann-type multicolor image hologram (image plane hologram). The wavelengths λ _1B and λ _{1R at} the time of this duplication are λ _1B / λ _0B = the wavelengths λ _0B and λ _{0R at} the time of recording the master 37.
It is assumed that λ _1R / λ _0R = C (for example, 1 is assumed to be the same). Then, from the form of equation (6), the same applies to λ ₁ / λ ₀ = C for B and R, and I ₁ does not depend on the wavelength. Therefore, in the case where the same θ and φ are provided for both B and R, the recording is performed with the same I ₀ for both B and R, and the same duplicate illumination light incident angle I ₁ is used for the duplication. Of course, it is also possible to similarly produce a multicolor recording Lippmann hologram with three or more colors.

In the multicolor recording Lippmann hologram thus manufactured, only the fringes having the required slant angle components are recorded with emphasis on each color, so that a bright multicolor hologram image can be obtained. In addition, in the arrangement of FIG.
By arranging the multicolor recording Lippmann hologram apart from the hologram, the produced multicolor recording Lippmann hologram becomes an image hologram, and even if illuminated with non-parallel white light during reproduction, a bright multicolor hologram image without blur can be observed.

Although the hologram duplication method and volume hologram of the present invention have been described based on the principle and the embodiments, the present invention is not limited to these, and various modifications are possible.

[0046]

As is apparent from the above description, according to the hologram duplication method and volume hologram of the present invention, a predetermined assumed illumination angle θ
In illuminated, since the incident replication illumination light at an incident angle I ₁ of the fringe of the assumed slant angle S _g as can be observed in a predetermined estimated observation central angle φ can replicate records, 0 based on the specular reflection
The diffraction of unnecessary light due to the next light or the like is limited, and the viewing range in which the recorded image can be observed is limited to a desired range. Therefore, a hologram image brighter than the original can be displayed.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method of recording a volume hologram master.

FIG. 2 is a diagram for explaining a hologram duplication method from a volume hologram master according to the present invention.

FIG. 3 is a diagram for explaining an assumed illumination angle and an assumed observation center angle of a copied volume hologram;

FIG. 4 is a diagram showing a relationship between a slant angle and a pitch of a fringe in comparison with a case of two duplicate illumination light incident angles.

FIG. 5 is a diagram showing a relationship between a slant angle of a fringe and a pitch in a specific numerical example.

FIG. 6 is a diagram qualitatively comparing a conventional volume hologram with a volume hologram by the hologram duplication method of the present invention.

FIG. 7 is a diagram for explaining a hologram duplication method when the hologram duplication method of the present invention is two-dimensionally extended.

FIG. 8 is a diagram for explaining one application example of a volume hologram duplicated by the hologram duplication method of the present invention.

FIG. 9 is a diagram for explaining another application example.

FIG. 10 is a diagram for explaining still another application example.

[Explanation of symbols]

O: Object O ': Object image 1 ... Volume hologram sensitive material 1' ... Original (first hologram original) 2 ... Illumination light (reference light) 3 ... Scattered light 4 ... Volume hologram sensitive material 4 '... Volume hologram 4 ₁ ... Volume hologram sensitive material 4 ₁ '... Second hologram master 4 ₂ ... Volume hologram sensitive material 5 ... Illumination light 5 ₁ ... Illumination light 5 ₂ ... Illumination light 6 ... Diffraction light 7 ... Illumination light 8 ... Fringe 10 ... Conventional Volume hologram, replicated volume hologram 11 ... diffracted light emitted in a predetermined observation direction 12 ... diffracted light emitted in a scattering direction 13 ... diffracted light equivalent to specularly reflected light 20 ... volume hologram 21 ... ground pattern 22 ... illumination light 23 ... Narrow viewing zone direction 24 Front direction 25 Volume hologram 26 Direction in viewing zone α ₁ 27 Direction in viewing zone α ₂ 28 Direction in range where viewing zone α ₁ and viewing zone α ₂ overlap 30 ... object 30 '... object image 31 B light scattering portion 32 ... R light scattering portion 33 ... B volume hologram photosensitive material 34 ... B illumination light 35 ... R volume hologram photosensitive material 36 ... R illumination light 37 ... original 38 ... BR volume hologram photosensitive material 39 ... BR replication illumination light

Claims (9)

[Claims] When replicating a volume hologram recording an image of a scattering object by a hologram duplication method, the duplicate hologram is illuminated at a predetermined assumed illumination angle θ.
Hologram replicating method for causing incident replication illumination light fringe assumed slant angle S _g as can be observed in a predetermined estimated observation center angle φ at an angle of incidence I ₁ which can be replicated recording. 2. The hologram duplication method according to claim 1, wherein said incident angle I ₁ satisfies the following equation (6). I ₁ = sin ⁻¹ << n ₁ / n ₀ × sin <± cos ⁻¹ [λ ₁ / (ν ₀ λ ₀ ) × cos ｛sin ⁻¹ (n ₀ / n ₁ × sin I ₀ ) − ｛sin ⁻¹ (N ₀ / n ₁ × sin θ) + sin ⁻¹ (n ₀ / n ₁ × sin φ)｝ / 2−τ ₀ ｝] + {sin ⁻¹ (n ₀ / n ₁ × sin φ) + sin ⁻¹ (n ₀ / n ₁ × sin θ)｝ / 2 −τ ₁ 〉>> (6) where I ₀ : original recording reference light incident angle λ ₀ : original recording wavelength ν ₀ : original photosensitive material contraction rate τ ₀ : original fringe slant Angle change λ ₁ : Duplicate wavelength τ ₁ : Duplicate fringe slant angle change n ₀ : Refractive index outside photosensitive material n ₁ : Refractive index inside photosensitive material 3. An original obtained by superimposing a first volume hologram recording an image of a first scattering object and a second volume hologram recording an image of a second scattering object in the same volume hologram photosensitive material. In the duplicated hologram, the hologram image of the first scattering object is illuminated at a predetermined assumed illumination angle θ, and a first predetermined assumed observation center angle φ
The fringe of the first assumed slant angle S _g1 that can be observed in ₁ and the hologram image of the second scattering object are illuminated at the predetermined assumed illumination angle θ, which is different from the _first assumed observation center angle φ _{1 Inject} duplicate illumination light at an incident angle I ₁ at which a fringe having an assumed slant angle S _g2 that can be observed at a _second predetermined assumed observation center angle φ ₂ , or similarly, three or more different fringes can be duplicated and recorded. The hologram duplication method according to claim 1 or 2, wherein: 4. A first volume hologram recording an image of a first scattering object at a first wavelength and a second volume hologram recording an image of a second scattering object at a second wavelength. When the original master is duplicated in the same volume hologram light-sensitive material, a third duplicated hologram in which the first wavelength and the wavelength ratio have a fixed relationship with respect to the hologram image of the first scattering object is obtained. the illumination light is irradiated at a predetermined assumed illumination angle theta, and a fringe of assumed slant angle S _g as can be observed in supposed observation center angle phi, the second wavelength and the wavelength ratio to the hologram image of the second scattering objects Are illuminated at a predetermined assumed illumination angle θ with a fourth illumination light having the same fixed relationship, and the same assumed observation center angle φ
In fringe same assumed slant angle S _g as can be observed, or, according to claim 1 or 2, characterized in that for entering a copy illumination light at an incident angle I ₁ that can replicate record three or more fringe different similarly Hologram duplication method. 5. When duplicating a volume hologram recording an image of a scattering object by a two-stage hologram duplication method,
In the duplicated hologram duplicated in the stage, the illumination is illuminated with a predetermined assumed illumination angle component θ _x in one of two directions orthogonal to each other along the hologram surface, and a predetermined assumed observation center angle component φ in that direction. _In the duplicate hologram replicated in the second stage, two orthogonal holograms are incident on the duplicate hologram replicated in the second stage, with duplicate illumination light being incident at an incident angle I _1x capable of replica recording a fringe having an assumed slant angle S _gx that can be observed at _x. Illuminate with a predetermined assumed illumination angle component θ _y in the other direction of the direction,
Hologram replicating method for causing incident replication illumination light fringe assumed slant angle S _gy as can be observed in its other direction of the predetermined estimated observation center angle component phi _y at an angle of incidence I _1y able to replicate record. 6. A volume hologram recording an image of a scattering object, which is illuminated at a predetermined illumination angle θ and has a slant angle around a fringe having a slant angle S _g that can be observed at a predetermined observation center angle φ. A volume hologram characterized in that only fringes having a slant angle within a predetermined width ΔS around S _g are recorded. 7. A volume hologram was recorded image of a scattering object, illuminated with a predetermined illumination angle theta, the slant around a fringe slant angle S _g1 as can be observed at a predetermined observation center angle phi ₁ Illuminating with a fringe of a slant angle within a predetermined width ΔS ₁ around the angle S _g1 and the predetermined illumination angle θ,
Another fringe of the slant angle S _g2 slant angle in the range [Delta] S ₂ given before and after the center of the another different fringe slant angle S _g2 as can be observed another of different predetermined observation center angle phi ₂ or, Similarly, only three or more different fringes are recorded. 8. A volume hologram in which an image of a scattering object is recorded, wherein a slant angle S _g illuminated with a first wavelength of illumination light at a predetermined illumination angle θ and observed at a predetermined observation center angle φ. Irradiating the fringe of the slant angle within a predetermined width ΔS ₁ around the slant angle S _g around the _first fringe and the illumination light of the second wavelength at the same predetermined illumination angle θ and the same predetermined observation Same slant angle S _g that can be observed at central angle φ
Characterized in that only a fringe of a slant angle within a predetermined width ΔS ₂ around the slant angle S _g around the _second fringe or only three or more different fringes are recorded. . 9. The hologram image is recorded so as to be reproduced near the hologram surface.
9. The volume hologram according to any one of items 1 to 8.