JP4127429B2 - Hologram production method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hologram manufacturing method, and more particularly to a Denniske hologram imaging method for imaging a subject with a single beam.
[0002]
[Prior art]
Conventionally, as a holographic imaging method, a single light beam is used, the light beam is once passed through a volume hologram light-sensitive material, and a subject placed behind the volume hologram light-sensitive material is illuminated, and scattered light and illumination light from the subject are volumetrically emitted. There is a hologram imaging method called a Denniske method that images a reflection type volume hologram by causing interference in a hologram sensitive material. Unlike the two-beam imaging method that uses object light and illumination light separately, this method has a feature in that the imaging optical system is simple.
[0003]
As a problem of this Denisuku method, the shape of the subject may be limited. For example, in the case of a subject with large unevenness, it is difficult to perform good hologram imaging with this imaging method. This problem will be specifically described with reference to FIG. In the Dennishoek hologram photographing method, a subject O is placed behind a volume hologram sensitive material 1 such as a photopolymer, and one light beam 2 is incident from the volume hologram sensitive material 1 side, and the light beam that has passed through the volume hologram sensitive material 1 is obtained. 2 illuminates the subject O. Then, by reflecting the light 3 scattered from the subject O and the incident light 2 in the volume hologram sensitive material 1, a reflection type volume hologram is photographed.
[0004]
[Problems to be solved by the invention]
In this Denniske method, the illumination light 2 is normally incident obliquely from above in order to enable observation at a natural angle during reproduction. However, when the subject O has large irregularities, the concave portion becomes a shadow, and the shape of the subject O in that portion is not recorded.
[0005]
In the example of FIG. 3, when photographing a doll with a hat in the eye as the subject O, when the illumination light 2 is incident obliquely from above, the face of the doll becomes a shadow portion A due to the eaves a of the hat and scattered from there. Since the light 3 is not generated, the portion A is not recorded as a hologram.
[0006]
The present invention has been made in view of such problems of the prior art, and an object of the present invention is to make it possible to record the surface shape of a subject with unevenness in the Denniske hologram imaging method.
[0007]
[Means for Solving the Problems]
The hologram production method of the present invention that achieves the above object includes disposing a hologram sensitive material on the illumination light side of the subject, making the illumination light incident from the hologram sensitive material side, and causing interference between the illumination light and the diffused light from the subject. In the method of photographing a hologram, a transmission hologram is arranged between the hologram sensitive material and the subject.
[0008]
In this case, the transmission hologram is desirably a volume hologram.
[0009]
Further, it is desirable that the transmission type hologram is to convert the object illumination angle of the illumination light transmitted through the hologram sensitive material.
[0010]
Further, it is desirable that the transmission hologram has a characteristic of transmitting part of the illumination light as 0th order diffracted light without diffracting it.
[0011]
In the present invention, since the transmission hologram is arranged between the hologram sensitive material and the subject, even if the subject has large irregularities, the whole can be illuminated without shadow to record the hologram. Therefore, in the Denniske hologram photographing method, even when the subject is illuminated from an oblique direction, it is possible to eliminate the deterioration of the hologram quality and the limitation of the shape of the subject itself due to the shadow on the subject.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the hologram manufacturing method of the present invention will be described with reference to the drawings.
In the present invention, in order to solve the problem that the shadow portion A of the subject O described with reference to FIG. 3 is not recorded as a hologram, a transmission type is provided between the subject O and the volume hologram sensitive material 1 as shown in FIG. By disposing the hologram 4 and changing the illumination light 2 that has passed through the volume hologram sensitive material 1 to illumination light 6 that is substantially perpendicular to the subject O by the transmission hologram 4, for example, the shadow A (FIG. 3) is eliminated. Is the method. By doing so, even when the subject O has large unevenness as described above, the entire object can be illuminated without shadow and recorded on a hologram.
[0013]
This will be described in detail with reference to FIG. Similar to the case of FIG. 3, a subject O is placed behind a volume hologram sensitive material 1 such as a photopolymer, and one light beam 2 is incident from the volume hologram sensitive material 1 side. At this time, the transmission hologram 4 is arranged between the subject O and the volume hologram sensitive material 1 as described above.
[0014]
Here, the transmission hologram 4 is a transmission hologram composed of a uniform Bragg grating recorded in the volume hologram sensitive material 10 in the arrangement as shown in FIG. That is, light 11 having the same wavelength as the illumination light 2 in FIG. 1 is incident at the same incident angle θ as that in FIG. 1 from the same side of the volume hologram sensitive material 10 such as a photopolymer, and another coherent light. By making 12 incident on the hologram sensitive material 10 at an angle θ ′ close to perpendicular, a transmission hologram 4 made of a uniform Bragg grating is recorded.
[0015]
This transmission hologram 4 converts the illumination light 2 incident at an incident angle θ into illumination light 6 emitted at an emission angle θ ′ on the transmission side, and is a volume hologram. It has the characteristic of allowing the scattered light 3 that is incident at angles other than the incident angle θ ′ to pass directly.
[0016]
Therefore, the illumination light 2 that has passed through the volume hologram sensitive material 1 is converted into, for example, illumination light 6 in a substantially vertical direction with respect to the subject O by the transmission hologram 4. Illuminated by a substantially vertical illumination light 6, no shadow is produced. Most of the light 3 scattered from the subject O passes through the transmission hologram 4 without being diffracted, enters the volume hologram sensitive material 1 from the back side and interferes with the incident light 2, thereby reflecting the entire subject O. A volume hologram is recorded.
[0017]
Here, when it is desired to emphasize the stereoscopic effect by adding a shadow to the subject O to the extent that there is no problem, it can be easily handled by changing the angle θ ′ of the diffracted light 6 from the transmission hologram 4 to a direction other than the vertical direction.
[0018]
In this way, in the Denniske method, by using the transmission hologram 4 that converts the angle of the illumination light 2, even when the subject O is illuminated at a natural illumination angle θ during reproduction, for example, 30 to 40 ° from the vertical, It is possible to eliminate the deterioration of the hologram quality caused by the shadow on the subject O and the limitation on the shape of the subject O itself.
[0019]
By the way, as described above, the light 3 that once hits the subject O and returns to the rear is already scattered light, so that there is little possibility of being diffracted again by the volume-type transmission hologram 4. However, when the surface shape of the subject O is close to a mirror surface and there are many components that are reflected substantially vertically, the ratio at which the scattered light 3 is diffracted again by the transmission hologram 4 and that portion cannot be recorded increases. In such a case, the problem can be addressed by suppressing the diffraction efficiency of the transmission hologram 4 and increasing the 0th-order light 5.
[0020]
The hologram manufacturing method of the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.
[0021]
【The invention's effect】
As is clear from the above description, according to the hologram manufacturing method of the present invention, since the transmission hologram is arranged between the hologram photosensitive material and the subject, even if the subject has large unevenness, the whole is illuminated without shadow. Hologram recording. Therefore, in the Denniske hologram photographing method, even if the subject is illuminated from an oblique direction, it is possible to eliminate the deterioration in the quality of the hologram and the limitation on the shape of the subject itself due to the shadow on the subject.
[Brief description of the drawings]
FIG. 1 is a diagram showing one optical arrangement for carrying out a hologram production method of the present invention.
2 is a diagram showing an optical arrangement for recording a transmission hologram used in FIG. 1; FIG.
FIG. 3 is a diagram for explaining a conventional method for photographing a hologram of Denniskek.
[Explanation of symbols]
O ... Subject A ... Shadow a ... Cap eaves 1 ... Volume hologram sensitive material 2 ... Illumination light 3 ... Scattered light 4 ... Transmission hologram 5 ... 0th order light 6 ... Illumination light after angle conversion (diffracted light)
10 ... Volume hologram sensitive material 11, 12 ... Light flux

Claims (3)

In a method of photographing a hologram by interference of illumination light and diffused light from a subject by placing a hologram sensitive material on the illumination light side of the subject, causing the illumination light to enter from the hologram sensitive material side, A hologram production method comprising: arranging a transmission hologram for converting the object illumination angle of the illumination light transmitted through the hologram sensitive material in between.   The hologram production method according to claim 1, wherein the transmission hologram is a volume hologram. The hologram production method according to claim 1 or 2 , wherein the transmission hologram has a characteristic of transmitting a part of the illumination light as zero-order diffracted light without diffracting part of the illumination light.

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