JPH09319289A - Exposure method for hologram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of the shadow of an object with irregularities by arranging a photosensitive material in the vicinity of the aperture part of a reflection mirror, arranging the object on the mirror surface side of the reflection mirror, irradiating the side of the object opposite to the reflection mirror side with light and reflecting the light by the reflection mirror, and irradiating the object with the reflected light and forming the object light. SOLUTION: The mirror surface side of the reflection mirror 20 has concave shape, which is formed by a rotary elliptical surface and on whose top the aperture part 22 is formed. The hologram photosensitive material 16 a little smaller than the aperture part 22 is arranged in the vicinity of the aperture part 22. Then, a subject 18 and an objective lens 11 are arranged on a focal point side nearly on the same axis linking two focal points of the rotary elliptical surface of the mirror 20. The hologram is exposed by the object light obtained by irradiating the side of the subject 18 opposite to the mirror 20 with the light, reflecting the light by the mirror 20 and irradiating the subject 18 with the reflected light. Thus, the light irradiating the subject 18 is radiated from nearly all the periphery in the forward direction of the subject 18, so that the object light having little shadow is obtaind even in the case the subject is very rugged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of exposing a hologram.

[0002]

2. Description of the Related Art Usually, in order to produce an image type Lippmann hologram, a Fresnel hologram to be a master hologram is produced as a first step, and then a conjugate reproduction is performed in a second step to produce a hologram. Often take the method of.

FIG. 2 is a conceptual diagram showing an optical system for producing a conventional master hologram. Here, 1 is a laser, 2 is a shutter, 4, 5 are beam splitters, 6, 7, 8 are mirrors, 11, 12, 13 are objective lenses, 15 are collimator lenses, 16 is a hologram photosensitive material, and 18 is It is a subject. The laser beam emitted by the laser 1 is split by the beam splitters 4 and 5, and the predetermined mirrors 6, 7 and 8 and the objective lenses 11 and 12,
The laser beam is expanded or collimated by using a collimator lens 13 and a collimator lens 15, and the hologram photosensitive material 16 and a subject 18 which is an object are irradiated with a spherical wave or a plane wave to produce a master hologram.

Next, FIG. 3 is a conceptual diagram showing an optical system for producing an image type Lippmann hologram based on this master hologram. Here, as in FIG. 2, 1 is a laser, 2 is a shutter, 6 is a beam splitter, 7, 10 are mirrors, 12 and 14 are objective lenses, 15
Is a collimator lens, 19 is a master hologram, 17
Is a hologram photosensitive material, and 20 is a reproduced image by a master hologram. The laser beam emitted by the laser 1 is split by the beam splitter 6, and the laser beam is expanded or made parallel by using predetermined mirrors 7, 10 and objective lenses 12, 14 and collimator lens 15, and the master hologram 19 and hologram Photosensitive material 17
Irradiate with spherical wave or plane wave. The master hologram 19 produced according to FIG. 2 is a reflection type, and the hologram photosensitive material 17 is conjugate-reproduced, the hologram photosensitive material 17 is placed near the center of the reproduced image 20, and the hologram photosensitive material 17 is irradiated with the reference light from one side. An image type hologram is produced.

When a master hologram is produced by this two-step production method, the laser light to be applied to the object may be from one direction, but the laser light is applied to the concave portion or the shadowed portion of the uneven subject. Therefore, illumination is often performed from two directions as shown in FIG.
However, it cannot be said that two directions are sufficient, and it is conceivable to further divide the beam and irradiate the object with laser light from multiple directions, but a large number of optical components such as beam splitters, mirrors, and lenses are required, and space is also required. Therefore, it was necessary to devise a method for producing a master hologram with such an uneven subject.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems existing in the prior art, and to provide a novel method of exposing and manufacturing a hologram which has not been known. is there.

This is a novel hologram exposure method which is particularly effective when an image-type Lippmann hologram is produced using an object having irregularities.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and irradiates a hologram photosensitive material with a reference beam from a first direction, and a second direction different from the first direction. In the method of exposing a hologram by irradiating the object light reflected from the object to expose the hologram, the photosensitive material is arranged in the vicinity of the opening of a reflecting mirror having a concave shape on the mirror surface side and having an opening at the top of the concave shape. Then, the object is arranged on the mirror surface side of the reflecting mirror, and light is radiated from the opposite side of the reflecting mirror side of the object to be reflected by the reflecting mirror, and the light reflected by the reflecting mirror is radiated to the object to illuminate the object light. The present invention provides a hologram exposure method characterized by forming the hologram.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the drawings. FIG. 1 is a conceptual diagram showing an optical system for producing a master hologram in the present invention.
Here, 1 is a laser, 2 is a shutter, 3 is a beam splitter, 6, 7 and 9 are mirrors, 11 and 12 are objective lenses, 15 is a collimator lens, 16 is a hologram photosensitive material, and 18 is a subject (object). , 20 are reflecting mirrors. In FIG. 1, the reflecting mirror 20 is represented by its cross section. The reflecting mirror 20 has a concave shape on the mirror surface side, and the concave shape is formed by a spheroidal surface. An opening 22 is formed at the top of the concave shape. Then, in the vicinity of the opening 22, the hologram photosensitive material 1 which is slightly smaller than the opening 22.
6 are arranged. The reflecting mirror 20 and the hologram photosensitive material 16 are fixed on a surface plate by jigs (not shown) so as not to be affected by disturbance such as vibration.

The reflecting mirror 20 in this example has a major axis length of 20c.
m is a spheroid with a minor axis length of 15 cm and the opening is about φ
It is formed to 17 cm. The reflecting mirror 20 is a PMMA base material that is mirror-finished by aluminum vapor deposition, but the base material may be glass and is not limited to this.

Further, the subject 18 is a letter or pattern indicating a company emblem of a manufacturing company, a name of a vehicle, and a vehicle class attached to an automobile or the like, which is a so-called ornament and has a long side of 55 mm and a short side of 45 mm. The elliptical shape was used. Then, its surface was coated with silver, and fixed on a disk-shaped aluminum plate to which a so-called non-reflective paper, which is hard to reflect, was attached, and fixed on a surface plate by a jig (not shown).

The spheroidal surface of the reflecting mirror 20 is 2
The object 18
And the objective lens 11 are arranged. One of the lights emitted from the laser 1 and split by the beam splitter 3 is reflected by the mirror 9 and irradiated toward the objective lens 11. Of the spherical waves emitted from the objective lens 11,
The central portion is blocked by the subject 18, and the outer peripheral portion is a reflecting mirror 20.
Head in the direction. Then, the light on the outer peripheral portion is reflected by the reflecting mirror 20 and is applied to the subject 18, and the reflection on the surface of the subject 18 becomes object light and is applied to the hologram photosensitive material 16. The other split light is reflected by the mirrors 6 and 7 and is applied to the hologram photosensitive material as reference light via the objective lens 12 and the collimator lens 15. Thus, due to the interference between the object light and the reference light,
Recording is performed on the hologram photosensitive material 16.

The light emitted to the subject 18 is emitted from almost the entire circumference in the front direction of the subject 18 except for the interruption by the jig for holding and fixing the subject 18, so that the object light has little shadow even in the subject having a lot of irregularities. Is obtained.

The positions of the subject 18, the objective lens 11 and the reflecting mirror 20 are appropriately set in consideration of the size of the subject 18 and the divergence of the laser beam by the objective lens 11. This reflecting mirror is an elliptic mirror. It is often set at a position other than the focal point of 20.

In this example, as the hologram photosensitive material 16, a hologram photosensitive material made of an acrylic photopolymer having a thickness of 20 μm, a length of 60 mm and a width of 80 mm was used.

As the hologram light-sensitive material, various light-sensitive materials such as other photopolymers, dichromated gelatin, and silver salts can be used. Especially when used as a master hologram, a material having a high sensitivity is used. It is preferable in that it is unlikely to be affected by the property and vibration.

In this example, a spheroidal reflecting mirror is used as a concave mirror surface, but not limited to an ellipsoidal surface, a parabolic surface, a spherical surface, or a cone-shaped conical body having an inner surface mirror-finished. The concave shape is not particularly limited as long as it is a concave shape capable of receiving light emitted from the back of the object and reflecting it toward the front surface of the object. Then, an opening is formed on the top of these so that the hologram photosensitive material can be arranged. Furthermore, three or more trapezoidal reflecting mirrors may be combined and joined to form a polygonal pyramid. In any case, the arrangement of the optical system is determined in consideration of the sizes and positional relationships of the object: the subject 18, the objective lens 11, the reflecting mirror 20, and the reflection of unnecessary light by the reflecting mirror.

It is also possible to partially change the reflectance of the reflecting mirror or roughen the surface of the reflecting mirror to produce a hologram having a soft feeling.

Using the master hologram produced by the above method, an image hologram made of an acrylic photopolymer was produced by the second step method shown in FIG. By attaching the hologram to the glass, it was possible to make a decorative decoration.

[0020]

According to the present invention, this method is suitable for producing an image hologram using an object having irregularities, and an excellent image hologram having less shadows on an object having irregularities is produced. can do.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of an optical system for exposing a master hologram in the present invention.

FIG. 2 is a conceptual diagram showing a conventional master hologram exposure optical system.

FIG. 3 is a conceptual diagram showing an optical system for exposing an image type hologram using a conventional master hologram.

[Explanation of symbols]

 1: Laser 2: Shutter 3, 4, 5: Beam splitter 6, 7, 8, 9, 10: Mirror 11, 12, 13, 14: Objective lens 15: Collimator lens 16, 17: Holographic photosensitive material 18: Subject 19 : Master hologram 20: Reconstructed image 21: Reflector

Claims (2)

[Claims] 1. A method of exposing a hologram by irradiating a hologram photosensitive material with reference light from a first direction and irradiating object light reflected by an object from a second direction different from the first direction. In the above, the photosensitive material is arranged in the vicinity of the opening of a reflecting mirror having a concave shape on the mirror surface side and having an opening at the top of the concave shape, and the object is arranged on the mirror surface side of the reflecting mirror to reflect the object. A method for exposing a hologram, which comprises irradiating light from a side opposite to the side, reflecting the light by a reflecting mirror, and irradiating the object with the light reflected by the reflecting mirror to form object light. 2. The hologram exposure method according to claim 1, wherein the concave mirror surface is formed of a cone, a paraboloid of revolution, or a spheroid of revolution.