DE2132328C - Surface reef hologram for reflection holography with a high degree of efficiency in reconstruction - Google Patents

Description

55

The present invention relates to a surface relief hologram for reflection holography with high efficiency in the reconstruction, consisting of a carrier, a recording medium and a reflective material applied to the recording medium Layer and a method for its production.

Will be suitable for holographic recording Medium processed such that the thickness of the medium varies according to the exposure that If the surface is corrugated in a relief-like manner, one speaks of a surface relief hologram. Such Surface relief holograms can be used in both photographic emulsions and photoresists. Manufacture thermoplastics and etchable materials with an applied photoresist layer.

A surface relief holo tree acts during the reconstruction in that its locally varying layer thickness the phase of the irradiated Again wave rotates. Is the recording medium transparent, this is how the reconstruction in transmission is explored. If, on the other hand, a If a reflective metal layer is applied, a reflection hologram is obtained. that through radiation the playback wave on the outside of the MeuU layer reconstructed v.ird.

Among the most important demands on a hologram The highest possible brightness counts and - \ ufUSung. As high a height as possible to achieve. is as high an efficiency as possible ■ löiiii. the LiN d.is ratio of the intensities of the reconstructed wave to the radiated reproduction h-wave is defined.

For its efficiency, the A;: - control of the gradation characteristic of the recording material with de :; imerisUatsvariationen des Inu - feren / field. by the nature of the material, and. ■ _ · Type of lioiogram determined.

When using photoresist or thermoph--; schem Materia! .. - Recording medium can often | ·: · _; -A low efficiency can be achieved in the reconstruction, especially if, in the interest of linear recording, only work with "rather small relief depths.; .- work!" or if only a small amount of energy is available during exposure;

The present invention is based on the object of providing an Obertlächcn Reüef hologram. in particular to indicate a RetlevionsholograniiTi, thereby eermeer relief depth in the reconstruction has particularly high efficiency.

In order to achieve this, it is proposed that the reflective layer be a further layer which is self-transparent Material with a wavelength for playback carries high refractive index, the surface of which is flat facing away from the relief side.

In a first preferred embodiment lsi the transparent material with a high refractive index ·. a solid from an organic polymerizable Fabric, such as hardening resin, thermoplastic or; of glass.

In another preferred embodiment according to the invention, the transparent material is with high refractive index an immersion liquid. like high-index oil.

A method for producing such a surface relief hologram is that After the light-sensitive layer has been exposed, it is developed and fixed with a reflective Layer is provided and then coated with a transparent, high-index material will.

Preferably, the light-sensitive layer between the subject is already during the exposure and light-sensitive layer a material with the same layer thickness and the same refractive index as in the reconstruction, which is removed again before developing.

In the case of interference, two non-diffuse light waves is in the case of a surface relief hologram operated in transmission according to the status of Technology, the phase shift Φ, the

nen light wave is a function of the amplitude of the relief fluctuation J, the light wavelength /, and the refractive index η of the hologram material and given by the following equation:

In the case of an Oherf surface relief hologram operated in reflection, the phase shift Φ ^ of the reflected light wave is given by:

0.

4 π J

15th

In the case of a reflection holocram, it is only applied.

Iranian. high index
Invention is the phases
reflected Liehtwelle

Layer after ^ shifter '/ ·.

that of the cleared areas can be removed. In this way, a surface relief phase hologram is obtained. If, on the other hand, thermoplastic plastic is used as the recording medium, this will be the best on a layer of transparent, photoconductive. Materials on electrically conductive, clear special glass base Applied / ur sensitization is the outer surface of the plastic an evenly distributed positive charge issued which a negative charge on ο the interface between the glass and foil conductor is influenced by the Exposure makes the photoconductor conductive where light is occurs, but remains in unexposed areas insulating. At the conductive points, the negative charges migrate through the photoconductor. at the interface to the plastic layer. After uv .: exposure, the arrangement is made by Viehlad'.ing liLhtunempfni '"' ch made.

/ ar Fntwicklupg ν ml of the plastic to / um Melting point heated. Chargers with positive, charges are thereby of the opposite negative " Are attracted, whereby one of the charge

V ₃ ■. distribution and thus the exposure ent-preclier-dj-

The surface relief is formed by cooling

is fixed. In this way also arises. c \\\

the refractive index of the applied 25 surface relief holes. being by vapor deposition a thin reflective metal layer e :: i reflection hologram is produced :; can.

In the following, the explanation will be based on the two Figures are explained in more detail.

F ^: 1 g. I shows a surface relief hologram using a solid refractive material and

F 1 g. 2 insert a surface relief hologram. ·! ι liquid high-quality material.

In the case of the in FIG. In the arrangement shown in FIG. 1, w :: 1 denotes the playback wave and?. Direct construction of electrical components. 3 is the Holo ^ rammlär'er 4 the relief layer. 5 the reflective overlay, for example a thin vapor-deposited metal layer. 6 denotes the transparent, highly refractive squint, which in the case of FIGS. 1 ordered from a solid. Organic polymerizable substances, such as hardening resin or thermoplastic, are particularly favorable. High-definition glasses are also suitable. Me 8 is an anti

VMO

is.

Never for distortion-free is the W! rkunesurad

where with / I ₁
Layer is designated.

With a small relief height.
Recordings required
proportional to Φ ·.

If a transparent material is chosen. whose 3 -.- · refractive index / ι, 2 is. Thus, with the arrangement according to the invention, there is either an increase in efficiency by a factor of 4 compared to the reflection hologram without a transparent layer, or, with the same efficiency, a relief height that is smaller by actuator 2, which represents a ciliebiichen gain in sensitivity of the hologram. Compared to a transmission hologram, the efficiency is even increased by a factor of 25 (for η 1.S).

The arrangement according to the invention has the great advantage that it is linear recording even with the increased degree of efficiency is preserved. There namely the efficiency

is a function of the phase shift 0, and thus 45 retrospectively also denotes the amplitude of the relief fluctuation d . is Dk arrangement according to the

the linearity of the reproduction is only guaranteed if if you are recording the hologram in linear part of the characteristic curve of the recording material remains. Due to the applied, transparent, high-index A linear amplification of the phase shift 0 by one is now achieved - 1 g. 2 corresponds to im

essential of the fig. 1. with the difference. dal. * the transparent high-index material 6 here consists of a liquid. The most suitable is an immersion liquid such as high-index OL With 7 a transparent cover plate is denoted !. which has anti-reflective layers 8 on both sides.

one

Factor which is equal to the refractive index H _{1 of} this layer. and thus an increase in efficiency.

Fire linear amplification of the phase shift 0 by linearly increasing the amplitude of the relief swan kung </ on the other hand is because of the non-linearity the characteristic curve of the recording material is often not possible.

Photoresists have proven to be particularly suitable recording media for Oherllächen relief hologramnios and thermoplastics proved.

one covers a glass plate with a layer

im the too

The antirellex layers 8 are preferably made dielectric layers and have the / wake. ! Beam path lying gron / I length up to actually make reflective pad 5 non-reflective.

To avoid aberrations it is

It is advisable to use the same transparent material when recording the hologram. or another the same refractive index, in every layer thickness to be stored in front of the photosensitive layer. as intended for playback.

Particularly suitable is the llolo-

for example, negative photoresist. so network 65 cramni to accommodate complex objects, such as the organic molecules of the lacquer under the FinfluB, for example, masks for the hologral atom Exposure and are thereby used for certain mask projection,> the dot matrix masks for holol insoluble while the non-graphic data storage.

For this 1 sheet of drawings

Claims (10)

Patent claims: 1. Surface relief hologram for reflection holography with high efficiency in the reconstruction, consisting of a carrier. a. Recording medium and a reflective coated on the recording medium Layer, characterized in that the reflective layer (5) a further layer (6) made of transparent material with one for the Playback wavelength carries high refractive index, the relief side (4) of which surface is even. 2. surface relief holoaramm according to claim characterized in that the ^s vhicht 16) Li ■ is organically polarizable material. 3 surfaces - relief hologram according to A.-sprucl: 2. characterized in that the organically polv merisable substance is a hänerdes resin is. 4. Surfaces - relief, ologram according to claim 2. characterized in that the organically polymerized substance is a thermoplastic. 5. surface relief hologram according to claim ! characterized in that the layer (6) is glass. 6. Surface relief hologram according to one of the preceding. '. Iisprüi'u. characterized, that the layer (6) at the same time HoIogranimträger is. ~. Surface - relief hologram according to claim 1, characterized in that the Layer (6) is an immersion liquid. S. Surfaces - Peliefhologram according to claim 7. characterized in that the immersion liquid is a high quality oil. 9. Process for the production of a surface Mi relief hologram according to one of claims 1 to s. characterized in that one on one Support applied light-sensitive layer is exposed, developed and fixed, with a stranded reflective layer and then with a transparent, high refractive index Material is coated. 10. Process for the production of a surface relief hologram nacl; Claim 9, characterized in that that during the exposure of the photosensitive layer between the subject and light-sensitive layer a material with the same layer thickness and the same refractive index as is brought in during the reconstruction, which is removed again before developing.