JPS5831371A - Production for hologram - Google Patents

Abstract

PURPOSE:To reproduce a hologram under the same condition as recording and to impart water resistance by forming a sensitized gelatin recording medium film on a substrate to obtain a hologram face and providing with protecting film where the optical film thickness is an integral maltiple of 1/2 of the wavelength of the recording and reproducing light, on this hologram face. CONSTITUTION:A sensitized gelatin recording medium 2 is formed on a transparent substrate 1, and a waterproof protection film 6 is provided on this recording medium 2, thus obtaining a hologram. An object light 3 and a reference light 4 are irradiated to this hologram and a reproducing light 5 is transmitted from the back of the substrate 1 to obtain a hologram recording medium. In the waterproof protection film 6 formed on the substrate 1, the optical film thickness determined by the product between a refractive index n1 and a geometric film thickness d1 is an integral multiple of 1/2 of a wavelength lambda of the recording and reproducing light 5. Since the protection film 6 protects the hologram face from moisture absorption and is ignored optically, the hologram is reproduced under the same condition as recording.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a hologram.

Dichromate gelatin recording media have high diffraction efficiency and 300
It is known as a hologram recording medium with a high resolution reaching 0 lines/square.

However, this recording medium swells with moisture, causing the recorded interference fringes to disappear and eventually resulting in no reproduced image, so conventionally a protective film such as epoxy resin was provided on the hologram surface. It is thought to protect eels from moisture absorption.

However, in conventional protective films of this type, the film thickness is determined to be an appropriate film without optical consideration, resulting in a decrease in transmittance and an increase in reflectance, resulting in a decrease in diffraction efficiency, and also in the case of holograms. There have been various drawbacks such as interference between the surface and the film, resulting in flare and ghost, resulting in a decrease in resolution.

This invention eliminates the drawbacks of the above-mentioned conventional ones and saves l1
It is an object of the present invention to provide a method for manufacturing a hologram in which the thickness of Ill[ is a film thickness that satisfies the same conditions as those that do not exist optically.

Jin's invention will be explained in more detail with reference to the drawings.

Figure 1.2 shows Ij! of hologram recording and reproduction, respectively.
, where 1 is the substrate, 2 is the recording medium, 3 is the object beam, and 4 is the
5 is a reference light, 5 is a reproduction light, and 6 is a protective film. Hold 1m
The optical properties of 1I6 are expressed by the following formula.

J = −aldlcOI p =
(λ Here, - is the phase angle, λ is the wavelength of the placed fist reproduction light,
Also, as shown in Figure 3.4, n is the refractive index of air, "l
is the refractive index of the protective film, nl is the refractive index of the hologram, -1 is the thickness of the protective film, and ψ can be determined by the refraction angle.Refractive index f of the leisure film
The optical thickness r1 is the product of i and the geometric thickness d.
The relationship between 1 dl and the reflectance of the protective film and the hologram is shown in FIG. 6. The phase angle - is also shown corresponding to the optical film thickness n14. From Figure 6, the optical thickness n1 of the protective film
dl is a multiple of ten times the wavelength l of the arrangement/reproduction light (i.e. -
〇 'l-i' * Goose 1. ), it can be seen that the reflectance of the protective film decreases and becomes the same as the reflectance of the hologram.

Example After recording a hologram with a He-N@ laser (J=ss2sl), /QA laxylylene (-=164) was formed as a protective film on the hologram surface (a@=153) to a thickness of 19Pm, and the diffraction efficiency and resolution were Good results were obtained with no substantial decrease in

As described above, this invention has a protective SiP that protects the hologram surface from rinsing and prevents the recorded interference fringes from disappearing, and since there is no optical protective film. Since the hologram is the same as the hologram, it can be reproduced under the same conditions as when it was placed, which has excellent effects such as preventing a decrease in diffraction efficiency and also preventing a decrease in resolution. It is.

[Brief explanation of the drawing]

Figure 1 is a 111.11 diagram of hologram recording, Figure 2 is a diagram of the principle of hologram reproduction, llgB, Figure 4 is a schematic diagram to explain the optical properties of the protective film, and Figure 5 is a diagram of the protective film. It is a graph showing the relationship between the optical film thickness and the reflectance of the hologram. l...board! ...Recording medium 8...Object light 4...Reference light 5...Reproduction light
6...HomH patent applicant Ricoh Co., Ltd. - Fan 1 Figure 2 Shoulder 3 Figure 4 Palm I/7 gland thickness (.1d,)

Claims (1)

[Claims] L An optical film consisting of the product of the refractive index and the geometric film thickness is formed on the hologram surface obtained by exposing the photosensitive gelatin recording medium to interference/#turn of light, borrowing it, and drying it. A method for manufacturing a hologram, comprising forming a protective film having a thickness that is an integral multiple of ten times the wavelength of recording/reproducing light.