JPH07225546A - Production fo reflection type hologram - Google Patents

Abstract

PURPOSE:To prevent incidence of noise light on a dry plate for hologram copying by improving a process for producing a reflection type hologram to be used for a head up display. CONSTITUTION:A master hologram 11 is formed by bringing a prism 12 which is plane in a position to be placed with a dry plate 13 for hologram copying at the time of copying and is formed of a transparent material having a refractive index approximately equal to the refractive index of the dry plate 11 for master hologram recording into tight contact with the front surface of the dry plate 11 for master hologram recording which records the hologram of the master and making recording light incident thereon from the rear surface of the plane of the prism 12 and the dry plate 11 for master hologram recording in the process for producing the reflection type hologram which forms the copy hologram copied from the master hologram 11 by using reflection diffracted light 232. The prism 12 is inserted between the formed master hologram 11 and the dry plate 13 for hologram copying in tight contact therewith respectively and copying light 231 is made incident thereon from the dry plate side 13 for hologram copying, by which the copyhologram is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a reflection type hologram used in a head-up display.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field, there is a head-up display described below. FIG. 10 is a diagram for explaining the outline of the head-up display. As shown in the figure, the head-up display includes a windshield combiner 200 and a hologram optical element 2 for projecting a display image on the windshield combiner 200.
01 and a display unit 202 including, for example, a CRT. According to the present head-up display, Bragg reflection is performed on the arbitrary light of the fluorescence emission spectrum from the display unit 202 by the hologram optical element 201, and a part of the light of the display unit 202 is reflected.
This is reflected by the windshield combiner 200 and made incident on the eyes of the driver. further. Hologram optical element 2
The image displayed on the display unit 202, for example, “80 k
"m / h" can be displayed at any distance. A conventional method for manufacturing the hologram optical element 201 will be described below.

FIG. 11 is a diagram for explaining a two-beam method for manufacturing an optical element using a conventional reflection hologram. As shown in the figure, the reflection hologram is generally a two-beam method in which one laser beam is divided into two and the two are exposed by irradiating them from the front and back of a hologram dry plate. But,
According to this two-beam method, since the optical path length to the dry plate is long, it is easily affected by fluctuations and vibrations of air, and it is necessary to wait for a long time until these are settled, which is not suitable for mass production. The solution to this is described below.

FIG. 12 is a diagram for explaining a hologram copy method for manufacturing an optical element using a conventional reflection hologram. A reflection hologram produced by the two-beam method is used as a master hologram 11, and another hologram copying dry plate 13 is placed in front of it as shown in this figure, and laser light is irradiated from the front side, and the laser light is used for hologram copying. There is a hologram copy method in which interference fringes generated by the diffracted light that has passed through the dry plate 13 and is diffracted by the master hologram 11 are recorded.

[0005]

However, the hologram copying method has the following problems. FIG. 13 is a diagram for explaining FIG. 12 in detail. As shown in the figure, the master hologram 11 is a master base glass 1
1a, a hologram surface 11b formed on it, and a master cover glass 11c for protecting it. The hologram copy dry plate 13 is the cover glass 1 of the master.
It is composed of a dry plate base glass 13a in contact with 1c and a gelatin film 13b on which a copy is formed. When laser light is emitted from the front surface for copying, reflected light at each interface and surface in addition to the diffracted light by the hologram is generated as noise light, which causes formation of a ghost image. Among the noise light shown in FIG. 3, the back surface reflected light a can be taken as a countermeasure for forming a ghost image by coating the back surface of the base glass 11a with black. In addition, the interface reflected light b due to the interface between the air gap between the master cover glass 11c, which is the substrate, and the dry plate base glass 13a, should be index-matched with silicon oil having a refractive index in combination with the glass. This makes it possible to take measures against the formation of ghost images. However, the hologram surface 11b on which the interference fringes are recorded is formed of a hologram photosensitive agent such as gelatin or photopolymer, and the refractive index is usually between the cover glass 11c of the master and the base glass 13a of the dry plate. There is a difference. Moreover, since it is difficult to adjust the refractive index, it is difficult to take measures against the reflected light c from the interface between the hologram surface 11b and the cover glass 11c.

Therefore, in view of the above problems, the present invention provides a hologram hologram surface 11b and a cover glass 1 in a reflection hologram manufacturing method for copying a master hologram 11 onto a hologram copy dry plate 13 using reflected diffracted light.
An object of the present invention is to provide a reflection hologram manufacturing method capable of preventing noise light due to reflection from the interface with 1c from entering the hologram copying dry plate.

[0007]

In order to solve the above problems, the present invention provides a method for producing a reflection hologram having the following constitution. In a reflection hologram manufacturing method for forming a copy hologram by copying a master hologram using reflected diffracted light, a hologram copy for forming a copy hologram at the time of copying on the front surface of a master hologram recording dry plate for recording a master hologram The dry plate is placed on a flat surface, and a prism made of a transparent material having a refractive index substantially equal to that of the dry plate is brought into close contact, and recording light is incident from the flat surface of the prism and the back surface of the master hologram recording dry plate. Form a hologram.

Next, the prisms are brought into close contact with each other between the formed master hologram and the hologram copy dry plate, and copy light is made incident from the hologram copy dry plate side to form a copy hologram. Further, on the front surface of the master hologram recording dry plate for recording the master hologram, the position for placing the hologram copy dry plate at the time of copying is a flat surface and is formed of a transparent material having a refractive index substantially equal to that of the master hologram recording dry plate. And a second prism identical to the first prism on the rear surface of the master hologram recording dry plate.
Alternatively, the master hologram may be formed by arranging the prism opposite to the arrangement of the prism and injecting the recording light from the planes of the first and second prisms.

Along with this, the first prisms are brought into close contact with each other between the formed master hologram and the hologram copy dry plate, and copy light is made incident from the hologram copy dry plate side to form a copy hologram. . Furthermore, even when noise light due to the interface between the master hologram and the prism is incident on the hologram copy dry plate during the production of the copy hologram, the direction of the diffracted light from the master hologram and the direction of the noise light are a predetermined amount. The apex angle of the prism may be determined so as to deviate by just that amount.

[0010]

According to the method of manufacturing the reflection type hologram of the present invention,
A prism is closely attached to the front surface of the master hologram recording dry plate to form the master hologram. A hologram of the master hologram is formed by bringing the prisms into close contact with each other between the master hologram formed in this way and the hologram copy dry plate, and forming copy holograms by entering copy light from the hologram copy dry plate side. The direction of the noise light due to reflection from the interface between the glass surface and the glass surface can be changed. Therefore, it is possible to prevent the noise light from entering the hologram copying dry plate, and it is possible to copy the hologram without being affected by the noise light, that is, without forming a ghost.

Further, when the direction in which the image reproduced by the copy hologram is viewed is limited, even if a ghost image formed by noise light is not visible, it is possible to reduce the apex angle of the prism. Therefore, the aberration due to the prism can be reduced, and the image distortion can be reduced. In addition, when the direction in which the image reproduced by the copy hologram is viewed is not limited and even a small ghost image is not allowed,
A first prism is closely attached to the front surface of the master hologram recording dry plate, and a second prism is arranged on the rear surface of the master hologram recording dry plate, which is opposite to the arrangement of the first prism,
Recording light enters from the planes of the first and second prisms to form a master hologram. Along with this, the first prisms are brought into close contact with each other between the master hologram and the hologram copy dry plate, and copy light is incident from the hologram copy dry plate side to form a copy hologram. A ghost image due to noise light can be removed without aberration.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an optical system for recording a master hologram in a reflective hologram manufacturing method according to an embodiment of the present invention. As shown in this figure, the prism 12
Has a front surface 12a and a rear surface 12b. Master hologram recording dry plate 11 for recording a master hologram
Is closely attached to the rear surface 12b of the prism 12. Laser diffused light 1 is emitted from the front surface 12a and the rear surface 12b of the prism 12.
31 and 132 (recording light) are incident, and the master hologram 11 in which the master hologram is recorded is formed.

FIG. 2 is a diagram showing an optical system for producing the copy hologram 13 by using the master hologram 11 in the reflective hologram production method according to the embodiment of the present invention. As shown in the figure, in the copy hologram production optical system, the master hologram 11 is brought into close contact with the rear surface 12b of the prism 12 having the same shape as when the master hologram was produced.
Next, on the front surface 12a of the prism 12, the master hologram 1
A large number of 1 can be copied by adhering a dry plate 13 for hologram copy. Laser diffused light 231 (copy light) is emitted from the front surface of the hologram copy dry plate 13, and the laser diffused light 231 that has passed through the hologram copy dry plate 13 is diffracted by the master hologram 11 to become diffracted light 232, which again becomes the hologram copy dry plate 13. Incident from the back side of. The incident diffracted light 232 from the back surface is the incident diffused light 23 from the front surface.
1 interferes with each other, whereby a copy hologram 13 is formed. In this case, the reflected light (noise light) at the interface between the hologram surface of the master hologram 11 and the glass surface travels in the direction indicated by the dotted line 233, and the hologram copy dry plate 13 is formed.
Does not enter. That is, the master hologram 11 is
By arranging them in a tilted manner with respect to the hologram copying dry plate 13 that is manufactured in large quantities, and filling the gap between them with the prism 12, the direction of noise light due to reflection from the interface between the hologram surface of the master hologram 11 and the glass surface can be changed.
Therefore, the noise light can be prevented from entering the hologram copy dry plate 13, and the hologram can be copied without being affected by the noise light, that is, without forming a ghost. Next, further improvement of this embodiment will be described.

First, problems to be improved will be described with reference to FIG. The diffracted light 232 of FIG. 2 passes through the prism 12 and then enters the hologram copying dry plate 13. For this reason, the prism 12 is provided on the hologram copying dry plate 13.
A hologram with the above aberration will be recorded. Therefore, when the apex angle α of the prism 12 is large, there is a problem that the reproduced image is distorted. In the above-described embodiment, the inclination of the hologram copy dry plate 13 with respect to the master hologram 11 is set so that noise light does not enter the hologram copy dry plate 13. However, when the normal reproduction image (reproduction image of the hologram recorded by the diffracted light) is viewed in a limited direction when reproducing the copied hologram, the ghost image of the noise light must be seen from that direction. In some cases, noise light may enter the hologram copy dry plate 13. Taking these points into consideration, the solution means will be described next.

FIG. 3 is a diagram showing a first modification of the optical system for recording the master hologram in the method of manufacturing a reflection hologram according to the embodiment of the present invention. In the recording optical system shown in this figure, the rear surface 12 of the prism 12 having a small apex angle α
The master hologram recording dry plate 11 is brought into close contact with b to record the master hologram. FIG. 4 is a diagram showing a first modification of the optical system for producing the copy hologram 13 using the master hologram 11 in the reflective hologram manufacturing method according to the embodiment of the present invention. As shown in the figure, at the time of copying, the master hologram 11 is brought into close contact with the rear surface 12b of the prism 12 having the same shape, and the hologram copying dry plate 13 is brought into close contact with the front surface 12a thereof. In this state, the front side is irradiated with laser diffused light 231 and the hologram is stored in the hologram copy dry plate 13. At that time, the noise light 233 due to the reflection from the interface between the hologram surface and the glass surface of the master hologram 11 enters the hologram copying dry plate 13 and forms a hologram on it. The reproduced image formed by the noise light will be described below.

FIG. 5 is a diagram showing reproduction of a ghost image formed by the copy hologram 13 of FIG. As shown in the figure, the reproduction direction of a ghost image generated by noise light during use is different from the reproduction direction of a normal image. Therefore, the ghost reproduction image cannot be seen from the position where the normal reproduction image is observed. FIG. 6 is a diagram showing an example of adjusting the arrangement of the display unit 202 and the hologram optical element 201 to prevent reproduction of a ghost image. As shown in FIG. 6, contrary to FIG. 5, the display unit 202 and the hologram optical element 20 are arranged in the traveling direction of the diffracted light.
With the configuration in which 1 is set, the reproduction light is incident from a direction different from the maximum efficiency incident direction of the copy hologram 13 formed on the noise light, so that a ghost reproduction image is hardly formed. As described above, according to the present method, the hologram copying dry plate 13 can be exposed with little influence of noise light and without causing the prism 12 to have an aberration because the apex angle α of the prism 12 is small. it can.

The above method cannot be applied when the viewing direction is not limited or when the generation of a slight ghost reproduction image is not permitted. For such a case, another improvement method will be described below. FIG. 7 is a diagram showing a second modification of the optical system for recording the master hologram in the reflective hologram manufacturing method according to the embodiment of the present invention, and FIG. 8 is a three-dimensional view of the optical system of FIG. As shown in FIGS. 7 and 8, when recording the master hologram, the first prism 1
The dry plate 11 for master hologram recording is brought into close contact with the rear surface 12b of 2. Further, the rear surface 14b of the second prism 14 having the same shape as that of the first prism 12 is brought into close contact with the dry side of the master hologram recording dry plate 11 opposite to the close contact surface. And FIG.
, The laser diffused light 131, 132 from the front surfaces 12a and 14a of the first and second prisms 12 and 14 is shown in FIG.
And the master hologram is stored in the master hologram recording dry plate 11.

FIG. 9 is a diagram showing a second modification of the optical system for producing the copy hologram 13 by using the master hologram 11 in the method for producing a reflection hologram according to the embodiment of the present invention. Next, when the copy hologram 13 is produced, as shown in FIG. 9, the hologram copy dry plate 13 is formed on the front surface 12a of the first prism 12 having the same shape as when the master hologram is recorded on the master hologram record dry plate 11. Put on. Furthermore, the first prism 1
The master hologram 11 is mounted on the rear surface 12b of the second lens 12. When the laser diffused light for copying is irradiated from the surface of the hologram copy dry plate 13, the hologram copy dry plate 13 is irradiated.
The laser light transmitted through is diffracted by the master hologram 11 and enters from the back surface of the hologram copy dry plate 13,
A hologram is recorded on the hologram copy dry plate 13. At the time of copying, the laser light diffracted by the master hologram 11 passes through the first prism 12 and then enters the hologram copy dry plate 13. This diffracted light passes through the second prism 14 during master recording. Since it is recorded on the master hologram 11 later, the chain line 13 in FIG.
It is equal to the ray indicated by 2 '. Therefore, the diffracted light can be regarded as light that has passed through the second prism 14 and the first prism 12. On the other hand, a surface 14a which is incident on the second prism 14 when recording the master hologram,
Surface 1 which is incident on the hologram copying dry plate 13 during copying
It is parallel to 2a. Therefore, after all, the diffracted light only passes through the flat plate sandwiched by the planes 13a and 12a, and the aberration of the prism hardly occurs. Thus, by using this method, even if a prism having a large apex angle α is used, almost no aberration occurs, so that noise light can be removed without aberration of the prism. When noise light may be incident, the influence of aberration can be further reduced by combining with the above method.

As described above, according to the present invention, it is possible to expose the hologram copying dry plate without generating a ghost image due to noise light.

[0020]

As described above, according to the present invention, the master hologram is formed by closely adhering the prism to the master hologram recording dry plate. By forming a copy hologram by using the master hologram thus formed with the prism interposed, the direction of noise light due to reflection from the interface between the hologram surface of the master hologram and the glass surface can be changed. Therefore, it is possible to prevent the noise light from entering the hologram copying dry plate, and the hologram can be copied without being affected by the noise light, that is, without forming a ghost image. Further, the aberration due to the prism can be reduced and the distortion of the image can be reduced, and the invention is not limited to this, and further, a ghost image due to noise light can be removed without the aberration of the prism.

[Brief description of drawings]

FIG. 1 is a diagram showing an optical system for recording a master hologram in a reflective hologram manufacturing method according to an embodiment of the present invention.

FIG. 2 is a diagram showing an optical system for producing a copy hologram 13 by using a master hologram 11 in a method for producing a reflection hologram according to an embodiment of the present invention.

FIG. 3 is a diagram showing a first modification of the optical system for recording the master hologram in the reflective hologram manufacturing method according to the embodiment of the present invention.

FIG. 4 is a diagram showing a first modification of the optical system for producing the copy hologram 13 by using the master hologram 11 in the method for producing a reflection hologram according to the embodiment of the present invention.

5 is a diagram showing reproduction of a ghost image formed by the copy hologram 13 of FIG.

FIG. 6 is a display unit 202 and a hologram optical element 2 in FIG.
It is a figure which shows the example which adjusts arrangement | positioning of 01 and prevents reproduction | regeneration of a ghost image.

FIG. 7 is a diagram showing a second modification of the optical system for producing the copy hologram 13 by using the master hologram 11 in the method for producing a reflection hologram according to the embodiment of the present invention.

8 is a three-dimensional view of the optical system of FIG.

FIG. 9 is a diagram showing a second modification of the optical system for producing the copy hologram 13 using the master hologram 11 in the method for producing a reflection hologram according to the embodiment of the present invention.

FIG. 10 is a diagram showing an outline of a head-up display.

FIG. 11 is a diagram illustrating a two-beam method for manufacturing an optical element using a conventional reflection hologram.

FIG. 12 is a diagram illustrating a hologram copy method for manufacturing an optical element using a conventional reflection hologram.

FIG. 13 is a diagram illustrating the details of FIG. 12;

[Explanation of symbols]

 11 ... Master hologram, master hologram recording dry plate 12 ... Prism, first prism 13 ... Copy hologram, hologram copy dry plate 14 ... Second prism 131, 132, 132 '... Recording light 200 ... Windshield combiner 201 ... Hologram Optical element 202 ... Display unit 231 ... Copy light 232 ... Diffracted light 233 ... Noise light

Claims (6)

[Claims] 1. A reflection hologram manufacturing method for forming a copy hologram by copying a master hologram using reflected diffracted light, wherein a copy hologram is formed at the time of copying on the front surface of a master hologram recording dry plate for recording a master hologram. A hologram copy dry plate for placing a flat plate, and a prism formed of a transparent material having a refractive index substantially equal to that of the dry plate is brought into close contact with the flat plate of the prism and the back surface of the master hologram recording dry plate to record light. To form a master hologram, the prisms are brought into close contact with each other between the formed master hologram and the hologram copy dry plate, and copy light is entered from the hologram copy dry plate side to form a copy hologram. A method of manufacturing a reflection hologram, which is characterized by the above. 2. A reflection hologram manufacturing method for forming a copy hologram by copying a master hologram using reflected diffracted light, wherein the copy hologram is formed at the time of copying on the front surface of a master hologram recording dry plate for recording a master hologram. A dry plate for hologram copying is placed on a flat surface, and a first prism formed of a transparent material having a refractive index substantially equal to that of the dry plate is closely attached to the rear surface of the dry plate for master hologram recording. The second prism, which is the same as the first prism, is arranged in the reverse of the arrangement of the first prism, and recording light is incident from the planes of the first and second prisms to form a master hologram. The first prism is closely adhered between the master hologram and the hologram copy dry plate for hologram copy. Reflection hologram manufacturing method characterized by forming a copy hologram is incident copying light from the plate side. 3. The method of manufacturing a reflection hologram according to claim 1, wherein the prism is formed of a transparent solid of at least glass and resin. 4. The direction of diffracted light from the master hologram and the direction of the noise light even when noise light due to the interface between the master hologram and the prism is incident on the hologram copy dry plate during the production of the copy hologram. The method of manufacturing a reflection hologram according to claim 1, wherein the apex angle of the prism is determined so as to shift by a predetermined amount. 5. The direction of the diffracted light from the master hologram and the noise light even when noise light due to the interface between the master hologram and the first prism is incident on the hologram copy drying plate during the production of the copy hologram. 3. The method of manufacturing a reflection hologram according to claim 2, wherein the apex angles of the first and second prisms are determined so as to deviate from the direction of 1. by a predetermined amount. 6. A hologram optical element for projecting a display image in a traveling direction of diffracted light when the copy hologram is used, and a display section are provided.
The method for producing a reflective hologram according to [4].