GB2119111A - Method and apparatus for making holograms - Google Patents

Abstract

A white light reflective hologram is made by exposing an object to a laser light beam and thereby forming a master hologram on a first holographic film. A secondary hologram is formed by exposing both the master hologram (7) and a holographic film (10) to a laser beam, and this may be repeated to produce a plurality of such secondary holograms from a single master. The secondary holograms may be used in security or identity cards or passes which can be verified by shining a source of light thereon to reveal the holographic image. <IMAGE>

Description

SPECIFICATION Method and apparatus for making holograms Field ofinvention This invention relates to a method of and apparatus for making holograms. Holograms are made by illuminating an object with a laser beam and recording an image of the object on holographic film, the image appearing three-dimensional.

Background to the invention Holograms have in the past been used for a variety of purposes, but the present invention was devised to provide a substantially tamper proof identity or security card which can be "read" by simple apparatus and which is therefore suitable to be carried by mobile personnel such as security guards. In particular, the invention aims to provide a method of making a hologram which is cheap to carry out so that holograms can be incorporated in security cards in large numbers at low cost.

Summary ofthe invention According to one aspect of the invention a method of making a white light reflective hologram comprises exposing an object to a laser light beam, forming a master hologram on a first holographic film from light reflected from the object, placing a second holographic film adjacent the master hologram, exposing both the second holographic film and the master hologram to a laser beam and thereby forming a secondary hologram on the second ho log- raphic film, the secondary hologram constituting the white light reflective hologram of the object.

In a preferred method, the second holographic film is laid above or on top of the master hologram before these components are exposed to the laser beam so as to transfer the image from the master hologram to the second holographic film. From a single master hologram, any number of secondary holograms can be formed by this process without the need for repeated exposure of the object to the laser beam.

In forming the secondary hologram a nonreflective glass plate is preferably interposed between the master hologram and the second holog raphicfilm, and further non-reflective glass plates may be placed underneath the master hologram and on top of the second holographic film before exposure of the stack thereby formed to the laser beam.

If desired, the master hologram may carry a plurality of images of the object, the plurality of images being arranged in a matrix or checkerboard pattern across the area of the first holographic film.

The master hologram may be formed with multiple images in this way either by exposing the object a plurality of times or by exposing the object once and producing multiple master images from one exposure. In either case the resulting master hologram has a plurality of images thereon so that a corresponding plurality of images is transferred to the second holographic film in the second stage of the process, giving a correspondingly increased number of holographic images on the second holographic film. This significantly reduces the cost of producing holograms, enabling large numbers to be produced more cheaply than by conventional methods.

The individual white light reflective holograms are particularly suitable for inclusion in a security or identity card or pass. For this application, the white light reflective hologram is preferably incorporated in or attached to a body of substrate or the card or pass in such manner that the hologram cannot be separated from the body or substrate without causing irreparable or apparent damage to the pass or card. A preferred method of doing this is to heat seal the hologram (which can withstand high tempera tures) to the body or substrate of the card or pass.

The hologram and the body or substrate may be incorporated in an envelope and heat sealed therein so that the envelope, hologram and body or substrate are inseparable.

For a security pass, the body or substrate may incorporate a photograph of the bearer or other identification, the hologram then being overlaid on top of the photograph bearing an identifiable image, such as the symbol or trademark of an organisation or Company to which the bearer belongs.

The invention also includes within its scope a white light reflective hologram made by the inventive method and a security or identity card or pass including such a white light reflective hologram.

Further, the invention includes within its scope apparatus for making a white light reflective hologram, the apparatus comprising means for supporting a first holographic film adjacent an object, a laser beam source for exposing the object to a laser beam so that the laser beam reflected from the object forms a master hologram on the first holographic film, a second holographic film for placing adjacent the master hologram and for accepting an image of the master hologram when the master hologram and the second holographic film are together exposed to a laser beam.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which Figure 1, is a side view showing apparatus for making a master hologram, Figure 2, illustrates how a secondary hologram is formed from the master hologram, and Figure 3, illustrates how a secondary hologram can be overlaid and sealed onto a body or substrate of a security or identity pass.

Detailed description of the drawings Referring to Figure 1, the apparatus shown therein comprises a frame having four upright columns (two of which are iilustrated at 1) between which are supported two trays 2 and 3. Each tray 2 or 3 is adjustable in height on the columns 1 by virtue of the columns having elongated slots 4 and means (such as a wing nut) for clamping the corner of each tray at a desired position along the length of the corresponding slot 4. Each tray 2 or 3 is formed by an outer frame of, for example, angle iron which supports on its horizontal flanges a glass panel. The object which it is desired to depict in the hologram is placed in the base of the frame and a first holographic film is placed between sheets or panels of non-reflective glass in one or other of the trays.A laser source produces a laser beam which is passed through a microscope lens, then through a screen with a hole to form a broad beam which is reflected from a mirror 6. The reflected beam passes downwardly to the object and is reflected therefrom, the incident and reflected light on the holographic film forming a holographic image or hologram of the object. This master hologram is used to produce a plurality of secondary holograms in the second stage of the process.

In the second stage of the process, the master hologram 7 is laid on a non-reflective glass plate 8 (Figure 2) supported on a horizontal surface. On top of the master hologram 7 are placed, in succession a second non-reflective glass plate 9, a second holog raphicfilm 10, and a third non-reflective glass plate 12. Each of the first and second holographic films is thus sandwiched between plates of glass.

The stack of components shown in Figure 2 is then exposed to a laser beam which is reflected from a mirror 13 downwardly onto the stack, in a manner comparable to that described for the first stage of the process. The frame of Figure 1 can be used for this second stage of the process, by appropriate vertical adjustment of the trays 2 and 3. As a result, the image from the master hologram 7 is transferred to the second holographic film 10 so as to provide the required white light reflective hologram.

As indicated in Figure 3, the white light reflective hologram 14 thus formed is laid on top of a body 15 of an identity pass which incorporates a photograph 16 of the bearer. The hologram 14 and the body 15 are placed in an envelope of plastics material, the envelope, the hologram and the body then being heat sealed together so that the hologram connot be separated from the body of the identity pass. When the resulting pass is viewed the photograph 16 of the bearer is visible with the holographic image appearing in three dimensional effect in front of the photograph. The holographic image may typically be a symbol of the security organisation so that all authorised members of the organisation would have an identity card bearing an individual photograph and a common hologram. An identity pass would then simply be placed under a source of light to verify it.

CLAIMS (filed on 18/4/83) 1. A method of making a white light reflective hologram, comprising exposing an object to a laser light beam, forming a master hologram on a first holographic film from light reflected from the object, placing a second holographic film adjacent the master hologram, exposing both the second holog raphicfilm and the master hologram to a laser beam and thereby forming a secondary hologram on the second holographic film, the secondary hologram constituting the white light reflective hologram of the object.

2. A method according to claim 1, wherein the second holographic film is laid above or on top of the master hologram before these components are exposed to the laser beam so as to transfer the image from the master hologram to the second holographic film.

3. A method according to claim 2, wherein in forming the secondary hologram a non-reflective glass plate is interposed between the master hologram and the second holographic film.

4. A method according to claim 3, wherein further non-reflective glass plates are placed underneath the master hologram and on top of the second holographic film before exposure of the stack thereby formed to the laser beam.

5. A method according to any of the preceding claims, wherein the master hologram carries a plurality of images of the object, the plurality of images being arranged in a matrix or checkerboard pattern across the area of the first holographic film.

6. A method according to claim 5, wherein the master hologram may be formed with the plurality of images either by exposing the object a plurality of times or by exposing the object once and producing multiple master images from one exposure.

7. A white light reflective hologram made by a method according to any of the preceding claims.

8. A security or identity card or pass including a hologram according to claim 7.

9. A security or identity card or pass according to claim 8, wherein the white light reflective hologram is incorporated in or attached to a body or substrate of the card or pass in such manner that the hologram cannot be separated from the body or substrate without causing irreparable or apparent damage to the pass or card.

10. A security or identity card or pass according to claim 9, wherein the hologram is heat sealed to the body or substrate of the card or pass.

11. A security or identity card or pass according to claim 10, wherein the hologram and the body or substrate are incorporated in an envelope and heat sealed therein so that the envelope, hologram and body or substrate are inseparable.

12. Apparatus for making a white light reflective hologram, the apparatus comprising means for supporting a first holographic film adjacent an object, a laser beam source for exposing the object to a laser beam so that the laser beam reflected from the object forms a master hologram on the first holographic film, a second holographic film for placing adjacent the master hologram and for accepting an image of the master hologram when the master hologram and the second holographic film are together exposed to a laser beam.

13. A method of making a white light reflective hologram, or apparatus for making a white light reflective hologram, substantially as herein particularly described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. placed between sheets or panels of non-reflective glass in one or other of the trays. A laser source produces a laser beam which is passed through a microscope lens, then through a screen with a hole to form a broad beam which is reflected from a mirror 6. The reflected beam passes downwardly to the object and is reflected therefrom, the incident and reflected light on the holographic film forming a holographic image or hologram of the object. This master hologram is used to produce a plurality of secondary holograms in the second stage of the process. In the second stage of the process, the master hologram 7 is laid on a non-reflective glass plate 8 (Figure 2) supported on a horizontal surface. On top of the master hologram 7 are placed, in succession a second non-reflective glass plate 9, a second holog raphicfilm 10, and a third non-reflective glass plate 12. Each of the first and second holographic films is thus sandwiched between plates of glass. The stack of components shown in Figure 2 is then exposed to a laser beam which is reflected from a mirror 13 downwardly onto the stack, in a manner comparable to that described for the first stage of the process. The frame of Figure 1 can be used for this second stage of the process, by appropriate vertical adjustment of the trays 2 and 3. As a result, the image from the master hologram 7 is transferred to the second holographic film 10 so as to provide the required white light reflective hologram. As indicated in Figure 3, the white light reflective hologram 14 thus formed is laid on top of a body 15 of an identity pass which incorporates a photograph 16 of the bearer. The hologram 14 and the body 15 are placed in an envelope of plastics material, the envelope, the hologram and the body then being heat sealed together so that the hologram connot be separated from the body of the identity pass. When the resulting pass is viewed the photograph 16 of the bearer is visible with the holographic image appearing in three dimensional effect in front of the photograph. The holographic image may typically be a symbol of the security organisation so that all authorised members of the organisation would have an identity card bearing an individual photograph and a common hologram. An identity pass would then simply be placed under a source of light to verify it. CLAIMS (filed on 18/4/83)

1. A method of making a white light reflective hologram, comprising exposing an object to a laser light beam, forming a master hologram on a first holographic film from light reflected from the object, placing a second holographic film adjacent the master hologram, exposing both the second holog raphicfilm and the master hologram to a laser beam and thereby forming a secondary hologram on the second holographic film, the secondary hologram constituting the white light reflective hologram of the object.

2. A method according to claim 1, wherein the second holographic film is laid above or on top of the master hologram before these components are exposed to the laser beam so as to transfer the image from the master hologram to the second holographic film.

3. A method according to claim 2, wherein in forming the secondary hologram a non-reflective glass plate is interposed between the master hologram and the second holographic film.

4. A method according to claim 3, wherein further non-reflective glass plates are placed underneath the master hologram and on top of the second holographic film before exposure of the stack thereby formed to the laser beam.

5. A method according to any of the preceding claims, wherein the master hologram carries a plurality of images of the object, the plurality of images being arranged in a matrix or checkerboard pattern across the area of the first holographic film.

6. A method according to claim 5, wherein the master hologram may be formed with the plurality of images either by exposing the object a plurality of times or by exposing the object once and producing multiple master images from one exposure.

7. A white light reflective hologram made by a method according to any of the preceding claims.

8. A security or identity card or pass including a hologram according to claim 7.

9. A security or identity card or pass according to claim 8, wherein the white light reflective hologram is incorporated in or attached to a body or substrate of the card or pass in such manner that the hologram cannot be separated from the body or substrate without causing irreparable or apparent damage to the pass or card.

10. A security or identity card or pass according to claim 9, wherein the hologram is heat sealed to the body or substrate of the card or pass.

11. A security or identity card or pass according to claim 10, wherein the hologram and the body or substrate are incorporated in an envelope and heat sealed therein so that the envelope, hologram and body or substrate are inseparable.

12. Apparatus for making a white light reflective hologram, the apparatus comprising means for supporting a first holographic film adjacent an object, a laser beam source for exposing the object to a laser beam so that the laser beam reflected from the object forms a master hologram on the first holographic film, a second holographic film for placing adjacent the master hologram and for accepting an image of the master hologram when the master hologram and the second holographic film are together exposed to a laser beam.

13. A method of making a white light reflective hologram, or apparatus for making a white light reflective hologram, substantially as herein particularly described with reference to the accompanying drawings.