JP2803377B2 - How to make a rainbow hologram - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to Rainbow holograms creating a single white light reproduction type display hologram, without any particular viewing area is limited,
It relates creating a rainbow hologram as a plurality of images without blurring other than the stereoscopic image may play continuously and clearly.

[0002]

2. Description of the Related Art In recent years, in the publishing or printing industries, holograms have been used as a means for preventing forgery of books, magazine covers, illustrations, gifts, novelties, or securities, credit cards, and IC cards. Is often used. There are various types of holograms of this type, and one of them is a white light reproducing rainbow hologram in which an image sequentially changes when the hologram is moved in one direction.

[0003] When a plurality of images are sequentially displayed with this kind of conventional rainbow hologram, one of the applied techniques is a technique of applying a holographic stereogram.

That is, a person sees an object and feels that it is three-dimensional because the left eye and the right eye look at the object at different positions (angles), and the images seen by both eyes are different. Therefore, if a two-dimensional image (two-dimensional image) when the subject is viewed from the position of the left and right eyes enters each eye, the subject image is perceived as a three-dimensional image (three-dimensional image). For this reason, if planar images obtained by photographing the subject from various positions can be observed from the corresponding positions, a display can be created in which the subject appears to exist at the original position. A display hologram that creates a three-dimensional image from a two-dimensional image by using the parallax of both eyes is called a holographic stereogram.

[0005] A normal holographic stereogram is composed of a vertically strip-shaped hologram recording a planar image of an object viewed from a different position, and a horizontal hologram corresponding to the position when the object is viewed. It is arranged in. Each strip-shaped hologram at this time is called an element hologram. When the holographic stereogram is reproduced and the image is viewed, the left and right eyes observe a planar image of the subject as viewed from each position through the element hologram. Therefore, the subject image is observed as a stereoscopic image. Observation with white light is made possible by creating a rainbow hologram from this holographic stereogram.

Hereinafter, a method for producing a rainbow hologram reproducible with white light using a holographic stereogram as a master hologram will be described.

FIG. 9 is a diagram showing a configuration example of an optical system for producing a rainbow hologram. That is, FIG.
, The laser beam output from the laser oscillator 20 is divided into a total reflection mirror 21 and a beam
The splitter (may be a half mirror) 22
Split into two laser beams. Then, one of the laser beams is reflected by the total reflection mirror 23, enters the lenses 24A and 24B, is sufficiently enlarged to be parallel light, and then has a slit 2 having a positional relationship as shown in FIG.
5, a part is selected and a master hologram (eg, holographic stereogram HS) 2
6 is incident. The other laser beam is reflected by the total reflection mirror 27, and the lenses 28A and 28B
And is sufficiently enlarged to become parallel light, and thereafter is incident on the photosensitive material 29 as reference light. In this case, of the light incident on the master hologram 26, the light diffracted here is also incident on the photosensitive material 29 as object light. As a result, interference fringes are formed on the photosensitive material 29 by the reference light and the light (object light) of the reproduced image formed as an image. By developing the photosensitive material on which the interference fringes are formed, a white light reproducing type is obtained. A rainbow hologram is obtained.

The rainbow hologram created by the above-described method is reproduced as shown in FIG. That is, as shown in FIG. 12, for example, when an eye is brought to the position of the slit reproduced by the green (G) wavelength, a reproduced image of the green (G) wavelength (color) is observed. This reconstructed image is an image recorded on the master hologram. Here, when the master hologram records a plurality of images as element holograms using the method of creating a holographic stereogram, the movement of the viewpoint in the horizontal direction in FIG.
Since the strip-shaped element hologram at the corresponding position is observed, an effect that the reproduced image is sequentially changed is brought about. On the other hand, the movement of the viewpoint in the vertical direction in FIG. 11 is a movement of the continuously reproduced slit image, and appears as a change in the observed wavelength. For example, if the eyes are shifted slightly downward in FIG. 11, the reproduced image observed at the wavelength (color) of green (G) gradually becomes longer in color, and the wavelength (color) of red (R) is gradually increased. ).

In summary, when observing a rainbow hologram, the movement of the viewpoint in the horizontal direction is perceived as a change in the observed image, and the movement of the viewpoint in the vertical direction is perceived as a change in the observed color. It is. Further, if the parallax images are recorded in the element holograms of the master hologram, the images reproduced differ depending on the positions of the left and right eyes of the observer, and can be recognized as a stereoscopic image.

[0010]

However, if a completely different image or moving image is recorded on each element hologram by using such a holographic stereogram creating method, the left eye of the observer can be obstructed. And the image observed with the right eye, ie, different images enter the eyes of the observer, the image is recognized as a blur (the image is doubled) and the desired image cannot be observed .

One solution to this problem is to make sure that the image always enters only one eye of the observer. As an example, while keeping the conventional rainbow hologram, it is possible to considerably limit the lateral direction of the slit, but this limits the viewing area to the distance between the left and right eyes of the observer. And
The viewing zone is so narrow that it is not practical.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and its object is to continuously and without blurring a plurality of images other than stereoscopic images without limiting the viewing area. Rainbow hologram that can be reproduced clearly
It is to provide a how to create.

[0013]

In order to achieve the above object, first, a laser beam output from a laser light source is split into two laser beams by an optical path splitting unit, and one of the laser beams is converted into parallel light. A part is selected by the rear slit, a master hologram is reproduced as reproduction light, the reproduced image is formed on a photosensitive material, and the other laser beam is made parallel light and then incident on the photosensitive material as reference light. Accordingly, an interference fringe is formed on the photosensitive material by the reference light and the light (object light) of the reproduced image formed as an image, and the white light reproducing type rainbow / rainbow obtained by developing the photosensitive material on which the interference fringe is formed is obtained. Ray in the hologram, which is the way the visible spectral region of reproducing the slit image, the viewer's left eye or the illumination light so that only one enter of the right eye is diffracted Create the baud hologram as follows:
To achieve .

That is, according to the invention described in claim (1), the laser beam output from the laser light source is split into two laser beams by the optical path splitting means, and one of the laser beams is converted into parallel light by the slit. By selecting a part to reproduce a master hologram as reproduction light and forming the reproduced image on a photosensitive material, converting the other laser beam into parallel light, and then making the other laser beam incident on the photosensitive material as reference light, An interference fringe is formed on the material by the reference light and the light (object light) of the reconstructed image formed, and the photosensitive material on which the interference fringe is formed is developed to form a reproduction slit.
In the visible spectral region S of the image, the left eye of the observer or
Illumination light is diffracted so that only one of the right eyes enters. <br/> A method for creating a white light reproducing rainbow hologram
A is, as a slit, reproduction slit images for the slit image which is reproduced at one particular wavelength range line, permeable to the direction inclined at the viewer's left eye and the tilt angle θ greater than or equal to the preset line connecting the right eye An optical part is formed and the tilt is
Angle θ, the visible spectral region S, and the left eye
From the pupil distance r of the right eye and θ = arctan (S /
The slit used in r) is used, and a master hologram in which a plurality of element holograms are arranged in a line is used as the master hologram.

In particular, in the invention described in claim ( 1 ), as the slit, a slit having a light-transmitting portion formed continuously is used, or the light-transmitting portion is intermittently corresponding to each element hologram. And a master hologram is formed from a series of element holograms created using a holographic stereogram creation method.

[0016]

Therefore, in the present invention, since the reconstructed image from the rainbow hologram can always be observed only by one eye of the observer, blurring of the image due to binocular parallax is eliminated. In addition, since the number of slits is unlimited in principle, the viewing zone is not limited.

As a result, a plurality of images other than a stereoscopic image without blur can be continuously and sharply reproduced, and a rainbow hologram which is extremely easy to see can be obtained.

[0018]

EXAMPLES In the present invention, when creating a white light reproduction type rainbow hologram in the case other than the target recognizing a stereoscopic binocular disparity, as a slit, against the one particular wavelength range line reproduction slit image Te, the use of slit light transmitting portion is formed in a direction inclined at an inclination angle θ as to incline the line connecting the viewer's left and right eyes, as a master hologram, a plurality of element holograms are arranged in a row When a rainbow hologram is observed, the rainbow hologram is diffracted so that only one of the left eye and the right eye of the observer enters the visible spectral region of the reconstructed slit image. -To obtain a hologram.

Hereinafter, an embodiment of the present invention based on the above concept will be described in detail with reference to the drawings.

As shown in FIG. 5, the rainbow hologram according to the present embodiment has only one of the left eye and the right eye of the observer (only the left eye in the figure) within the visible spectral region S of the reconstructed slit image. The illumination light is diffracted so as to enter.

Next, a specific method for producing a rainbow hologram according to this embodiment will be described.

First, an elementary hologram sequence (master hologram) is created by using a holographic stereogram optical system as shown in FIG. That is, FIG.
In, the laser beam output from the laser light source 1 is split into two laser beams by a total reflection mirror 2 and a beam splitter (may be a half mirror) 3 serving as an optical path splitting unit. Then, one of the laser beams is reflected by the total reflection mirror 4 and the total reflection mirror 5, enters the lenses 6A and 6B, is sufficiently enlarged to be parallel light, and then is partially selected by the slit 7, and is selected as reference light. Light is incident on the photosensitive material 8. The other laser beam enters the lenses 9A and 9B and is sufficiently enlarged to become parallel light, and as object light, a film of a 35 mm camera (any spatial modulation element may be used).
A two-dimensional image is projected on a screen 12 through 10 and a lens 11, and an element hologram is photographed on a photosensitive material 8 through a slit 7 to obtain a master hologram.

FIG. 3 is an enlarged schematic view showing the positional relationship among the slit 7, the photosensitive material 8, and the screen 12 in FIG. Here, the slit 7 is only required to select a part of the light, that is, only to shield unnecessary light. In this example, as shown in the figure, a slit having a light transmitting portion formed in the vertical direction is used. Used. Further, in FIG. 3, the slit 7 and the photosensitive material 8 are shown as being separated from each other, but actually, they are arranged in a state of being very close to each other.

Next, a method for producing a rainbow hologram reproducible with white light will be described.

That is, in this embodiment, an element hologram array 13 as a master hologram created by the above optical system and a slit 14 having a positional relationship as shown in FIG. Using the optical system in which the master hologram 26 and the slit 25 of the optical system are replaced with the element hologram row 13 and the slit 14,
A rainbow hologram is created in exactly the same way as in the case described above.

Here, the features of this embodiment are as follows.
As the slit 14, as shown in FIG. 5, an inclination angle θ that inclines a line connecting the left eye and the right eye of the observer (r indicates a distance between pupils) with respect to a specific wavelength band line of the reproduced slit image. In addition to using slits whose light transmitting portions are intermittently formed in correspondence with each element hologram, a plurality of strip-shaped element holograms are formed as master holograms with respect to a line connecting the left and right eyes of the observer. This is to use element hologram rows that are arranged in a row at predetermined intervals in a direction (vertical direction in the drawing) orthogonal to the above. In addition, each small translucent part in the slit shown in FIG.
This is equivalent to a light-transmitting part in a conventional slit.

Next, in the rainbow hologram created by the above-described optical system, the color of the slit image changes with respect to the movement of the viewpoint in the vertical direction. Further, the movement of the viewpoint in the horizontal direction involves both the movement from one slit to another slit and the change in color. That is, FIG. 1 shows the reproduced slit image as
Three typical wavelengths of R, G, and B are illustrated as examples (the dotted line in the drawing is the visible spectrum, the area where the slit is reproduced). For example, when an eye is placed on the R slit position, a reproduced image of the hologram can be observed at the R wavelength (color). Actually, slit images of all wavelengths are continuously formed, and when the observation direction is moved in the vertical direction in the figure, the reproduced image of the hologram can be observed while the color changes like a rainbow.

Accordingly, in such a rainbow hologram, if the inclination angle θ of the light-transmitting portion of the slit 14 is set appropriately, the image of the slit always enters only one eye of the observer, that is, the image from the hologram. Since the reconstructed image can always be observed only by one eye of the observer, blurring of the image due to binocular parallax is eliminated. In addition, since the number of slits is unlimited in principle, the viewing zone is not limited. As a result, it is possible to continuously and sharply reproduce a plurality of images having no blur other than the stereoscopic image, and to obtain a rainbow hologram that is extremely easy to see.

Next, the inclination angle θ of the light transmitting portion of the slit 14 will be described more specifically with reference to FIGS.

Generally, the angle of incidence of light on the diffraction grating is α,
Assuming that the first-order diffraction angle is β, the lattice constant is d, and the wavelength of light is λ, λ = d (sin α + sin β) (1) (α and β are ± as shown in FIG. 6).
Value). If this is solved for β, β = arcsin {(λ / d) −sinα} (2) Here, the time of reproducing the rainbow hologram of the present embodiment will be considered. Now, let the longest wavelength of the visible spectrum be λ _R ,
If the diffraction angle is β _R , the shortest wavelength is λ _B , and the diffraction angle is β _B , then from equation (2), β _R = arcsin ｛(λ _R / d) -sin α｝ (3) β _B = arcsin ｛(λ _B / d) −sin α｝ (4)

On the other hand, as shown in FIG. 7, consider the case where observation is made at a position L from the hologram surface. Now, assuming that the range of the visible spectrum at the eye position is S,

[0032]

(Equation 1) By substituting equations (3) and (4) into equation (5),

[0033]

(Equation 2) Becomes Further, assuming that the distance between the pupils of the observer is r, the inclination angle θ of the translucent portion of the slit is as follows: θ = arctan (S / r) (7)

[0034]

(Equation 3) Becomes From the equation (8), it is possible to calculate an appropriate inclination angle θ of the light transmitting portion of the slit.

For example, if the visible spectrum is 400 to 750
nm, the angle α of incident white light is 45 °, the lattice spacing d of the hologram is 2 μm, and the distance L from the hologram surface to the eye is L.
= 200 mm and the interpupillary distance r = 70 mm, the inclination angle θ of the translucent portion of the slit is obtained as follows: θ = 34.0 degrees. In other words, under this condition, if the slit is inclined at 34.0 degrees or more, the image is not reproduced at both eyes of the observer at the same time, and the blur is eliminated.

[0036] As described above, in the present embodiment, when creating a rainbow hologram of the white light reproduction type, as a slit, for the one particular wavelength range line reproduction slit image, the observer's left eye A plurality of strip-shaped element holograms are observed as a master hologram while using a slit 14 in which a light-transmitting portion is intermittently formed corresponding to each element hologram at an inclination angle θ that inclines a line connecting the right eye. By using element hologram rows 13 arranged in a row at predetermined intervals in a direction substantially orthogonal to the line connecting the left and right eyes of the observer, the observer's left eye or The illumination light is diffracted so that only one of the right eyes enters.

Therefore, by appropriately setting the inclination angle θ of the light transmitting portion of the slit 14, the image of the slit always enters only one eye of the observer, that is, the reproduced image from the hologram is always observed. Since the image can be observed only by one eye of the person, blurring of the image due to binocular parallax can be eliminated.

In principle, the number of the slits 14 is unlimited, so that the viewing zone can be prevented from being limited. This makes it possible to continuously and sharply reproduce a plurality of images other than a stereoscopic image without blurring, and to obtain a rainbow hologram that is extremely easy to see.

In addition, the intermittent slits 14 allow the master hologram to be used more efficiently during rainbow hologram creation, and thus the rainbow hologram created is more efficient than the linear case described above. A bright and easy-to-see one can be obtained.

It should be noted that the present invention is not limited to the above-described embodiment, and can be similarly implemented, for example, as follows.

(A) In the above embodiment, a method for producing a rainbow hologram reproducible with white light using the element hologram array produced by the production method of the present invention as a master hologram has been described. May be used as a master hologram to create a rainbow hologram that can be reproduced with white light.

(B) In the above embodiment, the case where a transparent type substrate is used and a rainbow hologram is formed from a series of transparent element holograms has been described. However, the present invention is not limited to this, and a reflective type substrate may be used. It is also possible to create a rainbow hologram from a reflective holographic stereogram. In this case, a part of the configuration of the optical system shown in FIG. 8 may be rearranged so that light diffracted by reflection from the reflection type holographic stereogram is incident on the photosensitive material.

(C) In the above embodiment, a case was described in which the slit 7 was a slit whose light transmitting portion was formed intermittently in correspondence with each element hologram. For example, as shown in FIG. 8, it is also possible to create a rainbow hologram from a holographic stereogram using a slit in which a light-transmitting portion is formed continuously. Such a linearly continuous slit is extremely easy to install and adjust when creating a rainbow hologram.

[0044]

According to the present invention described above, according to the present invention, when creating a master hologram white light reproduction type rainbow hologram, as a slit, for the one particular wavelength range line reproduction slit image, A slit formed with a light-transmitting portion in a direction inclined at a preset inclination angle θ of a line connecting the left eye and the right eye of the observer,
As the master hologram, a master hologram in which a plurality of element holograms are arranged in a line is used, and the illumination light is diffracted so that only one of the left eye and the right eye of the observer enters the visible spectral region. Therefore, it is possible to provide a method for producing a rainbow hologram capable of continuously and clearly reproducing a plurality of images without blurring other than a stereoscopic image without limiting the viewing zone.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a rainbow hologram according to the present invention.

FIG. 2 is a schematic diagram showing a configuration example of an optical system for creating a master hologram (element hologram row) in the embodiment.

FIG. 3 is an enlarged schematic view showing a positional relationship between a slit, a photosensitive material, and a screen in FIG. 2;

FIG. 4 is a schematic diagram showing a configuration example of a slit in the embodiment.

FIG. 5 is a view showing, as an example, three representative R, G, and B wavelengths of a slit image reproduced in the rainbow hologram of the embodiment.

FIG. 6 is a conceptual diagram for explaining the operation in the embodiment.

FIG. 7 is a conceptual diagram for explaining the operation in the embodiment.

FIG. 8 is a schematic diagram showing another configuration example of the slit according to the present invention.

FIG. 9 is a schematic diagram showing a configuration example of an optical system for creating a rainbow hologram.

FIG. 10 is a schematic diagram showing a configuration example of a conventional slit in FIG. 9;

FIG. 11 is a schematic view showing an example of a conventional rainbow hologram.

FIG. 12 is a diagram showing a slit image reproduced in the rainbow hologram of FIG. 11 using three typical R, G, and B wavelengths as an example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser light source 2 total reflection mirror 3 beam splitter 4 total reflection mirror 5 total reflection mirror 6
A, 6B: lens, 7: slit, 8: photosensitive material, 9
A, 9B: lens, 10: film, 11: lens, 1
2 ... Screen, 13 ... Master hologram, 14 ...
Slit, 20: laser oscillator, 21: total reflection mirror,
22: beam splitter, 23: total reflection mirror, 2
4A, 24B: lens, 25: slit, 26: master hologram, 27: total reflection mirror, 28A, 28B
... Lens, 29 ... Photosensitive material.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03H 1/26 G03H 1/04

Claims (4)

(57) [Claims] 1. A laser beam output from a laser light source is split into two laser beams by an optical path splitting means.
After making one laser beam a parallel light, a part is selected by a slit, a master hologram is reproduced as a reproduction light, and the reproduced image is formed on a photosensitive material. By making the light incident on the photosensitive material, an interference fringe is formed on the photosensitive material by the reference light and light (object light) of a reproduced image formed as an image, and the photosensitive material on which the interference fringe is formed is formed. By developing, within the visible spectrum region S of the reproduced slit image
Only one of the observer's left or right eye
A method of sea urchin illumination light to create a rainbow hologram of the white light reproduction type that is diffracted, as the slit, for the one particular wavelength range line reproduction slit images, connecting the viewer's left and right eyes line Are formed in a direction inclined at an angle equal to or greater than a preset inclination angle θ , and the inclination angle θ is set to the visible spectrum.
Area S, and the distance r between the pupils of the left eye and the right eye
A rainbow hologram is produced, wherein a slit having θ = arctan (S / r) is used, and a master hologram in which a plurality of element holograms are arranged in a line is used as the master hologram. Method. 2. The method for producing a rainbow hologram according to claim 1, wherein a slit having a light transmitting portion formed continuously is used as said slit. 3. A rainbow hologram according to claim 1, wherein said slit is a slit having a light-transmitting portion intermittently formed corresponding to each of said element holograms. Method. 4. The rainbow hologram creation according to claim 1, wherein an element hologram row created using a holographic stereogram creation method is used as the master hologram. Method.