US3821722A - Method of effecting cyclic reversible holographic recording in a thermo plastic material - Google Patents

Method of effecting cyclic reversible holographic recording in a thermo plastic material Download PDF

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Publication number
US3821722A
US3821722A US00360768A US36076873A US3821722A US 3821722 A US3821722 A US 3821722A US 00360768 A US00360768 A US 00360768A US 36076873 A US36076873 A US 36076873A US 3821722 A US3821722 A US 3821722A
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United States
Prior art keywords
thermoplastic material
sensitizing
holographic recording
recording
charge
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Expired - Lifetime
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US00360768A
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English (en)
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J Ost
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Siemens AG
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Siemens AG
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G16/00—Electrographic processes using deformation of thermoplastic layers; Apparatus therefor

Definitions

  • This invention relates to a method for effecting cyclic, reversible, holographic recording in a thermoplastic material, and is more particularly concerned with such holographic recording in which, prior to each new recording cycle, the thermoplastic material is placed adjacent a corona charge at a positive or negative potential and thus sensitized. Afterward holographic exposure is carried out and the resultant hologram is developed by heating and fixed by cooling.
  • the photoconductor becomes conductive at points where light is incident, whereas at unexposed locations it continues to insulate. At the conductive locations, the charges pass through the photoconductor up to the interface with the synthetic material layer. After exposure, the arrangement is rendered insensitive to light by a secondary charge.
  • the synthetic material is heated up to the softening point. In so doing, locations carrying positive charges are attracted by the opposite negative charges, and vice versa, so that a surface relief formation is produced corresponding to the charge distribution and therefore to the exposure, and this surface relief is fixed by cooling. In this manner, a surface phase hologram is produced.
  • the hologram can be erased again if the layer is heated to above the softening point. Surface forces here, again, generate a smooth layer surface and the synthetic layer can again be used for recording.
  • thermoplastic materials are particu larly significant where holographic storage is concerned. Also, the photosensitivity of the thermoplastic materials of this type is at least as good as that of conventional photographic emulsions.
  • the reduction in the signal to noise ratio, and therefore the reduction in image quality and in efficiency, may be traced to several factors.
  • the properties of the thermoplastic material deteriorates because of the thermaloading applied during development and erase phases.
  • deterioration occurs because of the residual charges left over from preceding recording cycles.
  • the electrostatic charges result in the absorption of dust at the layer surface, which dust, during the development and erase processes, when the layer softens, becomes embedded in the layer.
  • the embedded dust particles act as condensation nuclei in the neighborhood of which the layer breaks up completely after a certain number of cycles.
  • the object of the present invention is to provide a method for the cyclic, reversible, holographic recording of a thermoplastic material of the type initially described, in which with an increasing number of cycles the signal to noise ratio is substantially better and therefore the image quality is substantially better than is the case in previously. known meth ods.
  • the present invention is based on the proposal that with an increasing number of re cording cycles, the corona charge voltage required for sensitizing is increased and that the thermoplastic material is thus placed in a progressively higher positive or negative potentials.
  • a layer carrier 3 which may, for example, comprise a transparent synthetic foil, is carried upon a grounded substrate 4. At its free surface, the layer carrier 3 supports a layer 2 which may comprise, for example, a mixture of a photoconductive and a thermoplastic material.
  • a corona charge device 1 is provided above the layer 2 and rendersit possible to produce at the free surface of the layer 2 a charge, for example a positive charge.
  • This charge sensitizes the thermoplastic material, the sensitizing being carried out in darkness.
  • the thermoplastic material 2 is holographically exposed and a charge profile corresponding to the optical interference pattern results wherein the charges migrate to the' exposed locations.
  • the development of the hologram is carried out thereafter by heating. By means of electrostatic forces, deformation of the free surface of the layer 2 is produced, this deformation being determined by the illumination energy.
  • rapid cooling a stable hologram is created which, by heating to a temperature higher than the developing temperature, can be erased again.
  • the layer 2 is sensitized prior to the first record/erase cycle using a relatively low corona charge voltage. This charge voltage is correspondingly increased as the number of cycles progresses, so that the thermoplastic material is placed at progressively higher positive or negative potentials.
  • a method of carrying out cyclic, reversible, holographic recording in a thermoplastic material comprising the steps of: creating a corona charge with a corona discharge voltage; sensitizing thermoplastic material with the corona charge prior to each new recording cycle; progressively increasing the corona discharge volt age to increase the corona charge for sensitizing prior to each new recording cycle; holographically exposing the sensitized thermoplastic material; heating the exposed material to produce a surface relief; and fixing the surface relief by cooling the thermoplastic material.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Holo Graphy (AREA)
US00360768A 1972-05-24 1973-05-16 Method of effecting cyclic reversible holographic recording in a thermo plastic material Expired - Lifetime US3821722A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2225266A DE2225266A1 (de) 1972-05-24 1972-05-24 Verfahren zur zyklischen, reversiblen, holografischen aufzeichnung in einem thermoplastischen material

Publications (1)

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US3821722A true US3821722A (en) 1974-06-28

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US00360768A Expired - Lifetime US3821722A (en) 1972-05-24 1973-05-16 Method of effecting cyclic reversible holographic recording in a thermo plastic material

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US (1) US3821722A (US07935154-20110503-C00018.png)
JP (1) JPS4951969A (US07935154-20110503-C00018.png)
BE (1) BE799982A (US07935154-20110503-C00018.png)
DE (1) DE2225266A1 (US07935154-20110503-C00018.png)
FR (1) FR2185829B1 (US07935154-20110503-C00018.png)
GB (1) GB1432976A (US07935154-20110503-C00018.png)
IT (1) IT1006052B (US07935154-20110503-C00018.png)
LU (1) LU67637A1 (US07935154-20110503-C00018.png)
NL (1) NL7307207A (US07935154-20110503-C00018.png)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970357A (en) * 1973-11-05 1976-07-20 Hoechst Aktiengesellschaft Apparatus for holographic recording
US3976354A (en) * 1973-12-14 1976-08-24 Honeywell Inc. Holographic memory with moving memory medium
US3995280A (en) * 1975-01-02 1976-11-30 Sperry Rand Corporation Method of monitoring thermoplastic recording
US3997238A (en) * 1974-09-30 1976-12-14 Ricoh Co., Ltd. Holographic recording process using a thermoplastic photosensitive member
US4014603A (en) * 1973-11-05 1977-03-29 Hoechst Aktiengesellschaft Method of holographic recording
FR2351432A1 (fr) * 1976-05-15 1977-12-09 Hoechst Ag Procede et dispositif pour l'enregistrement et la reproduction optique d'images radiographiques
US4103214A (en) * 1975-03-12 1978-07-25 Honeywell Inc. Error cancelling sync-off-tach tape drive system
US4174881A (en) * 1976-03-05 1979-11-20 Rca Corporation Recording a synthetic focused-image hologram on a thermally deformable plastic

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970357A (en) * 1973-11-05 1976-07-20 Hoechst Aktiengesellschaft Apparatus for holographic recording
US4014603A (en) * 1973-11-05 1977-03-29 Hoechst Aktiengesellschaft Method of holographic recording
US3976354A (en) * 1973-12-14 1976-08-24 Honeywell Inc. Holographic memory with moving memory medium
US3997238A (en) * 1974-09-30 1976-12-14 Ricoh Co., Ltd. Holographic recording process using a thermoplastic photosensitive member
US3995280A (en) * 1975-01-02 1976-11-30 Sperry Rand Corporation Method of monitoring thermoplastic recording
US4103214A (en) * 1975-03-12 1978-07-25 Honeywell Inc. Error cancelling sync-off-tach tape drive system
US4174881A (en) * 1976-03-05 1979-11-20 Rca Corporation Recording a synthetic focused-image hologram on a thermally deformable plastic
FR2351432A1 (fr) * 1976-05-15 1977-12-09 Hoechst Ag Procede et dispositif pour l'enregistrement et la reproduction optique d'images radiographiques

Also Published As

Publication number Publication date
JPS4951969A (US07935154-20110503-C00018.png) 1974-05-20
IT1006052B (it) 1976-09-30
FR2185829A1 (US07935154-20110503-C00018.png) 1974-01-04
FR2185829B1 (US07935154-20110503-C00018.png) 1976-11-12
DE2225266A1 (de) 1973-12-06
BE799982A (fr) 1973-09-17
NL7307207A (US07935154-20110503-C00018.png) 1973-11-27
LU67637A1 (US07935154-20110503-C00018.png) 1973-07-26
GB1432976A (US07935154-20110503-C00018.png) 1976-04-22

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