Title of Invention	A MASTER HOLOGRAM AND AN APPARATUS FOR THE MANUFACTURE OF INDIVIDUAL HOLOGRAMS
Abstract	This invention relates to a multiple master hologram for the copying of a hologram in a contact process, characterized in that the total master comprises preferably three individual masters which each bear different information, and the individual masters are positioned in a fixed relation to one another in the manufacture of the hologram or contact hologram,

Full Text

-1A- The invention relates to a master hologram for the copying of a hologram in a contact process. The invention further relates to an apparatus for the manufacture of an individual hologram, in particular of a contact copy of a hologram, with a radiation source with laser radiation for the irradiation of a master and a film. The invention finally relates to a hologram, in particular a copy of a contact hologram. The individual holograms can be used to make documents secure. In the manufacture of holograms, a master hologram and a holographic film are irradiated with laser radiation. In the series production of holograms, the holograms are preferably manufactured by means of a contact copy. In this case, the master and the film are in contact with each other. On the holographic film, a hologram is created with the information present on the master. Accordingly, with a master, holograms which all contain the same information can be manufactured simply in series production. If, however, the holograms should contain fully or partially different, individual information, difficulties arise in series production. For each hologram, a separate master must then be prepared. This is time-consuming and expensive. It is the object of this invention to provide a master for the copying of a hologram, in particular by means of a contact copy, with which holograms which contain different information can be manufactured in a simple manner. 2 This object is solved in accordance with the invention by the master comprising multiple, preferably 3, individual masters which each bear different information. Advantageous improvements are described in the dependent claims. Preferably, the first master hologram is the hologram of a ground glass screen. Another advantageous embodiment is characterised in that stimulation holograms are manufactured from the master hologram(s). The stimulation holograms serve to shape the coherent radiation. The stimulation hologram here is designed in such a way that it predominantly guides the coherent radiation into predetermined regions on the master and the film in which holograms or hologram components are to be generated. In this way, the efficiency or the radiation yield is substantially improved. The stimulation hologram can be manufactured as a computer-generated hologram (CGH). However, it can also be manufactured interferometrically. In accordance with another advantageous improvement of the invention, a colour device is available for the colour irradiation of the master and the film. In this way, it is possible, for example, to produce the individual hologram, that is that component of the hologram bearing individual information, in colour. Preferably, a colour-capable LCD is used. This can have white-light lasers transmitted through it or, however, three differently coloured lasers in the standard colour triangle. In accordance with another advantageous improvement, an apparatus to expose different aspect angles is provided. Both monochrome and multi-colour holograms can be exposed with different aspect angles. In this way, it is possible to generate a stereogram or a multi-stereogram which can be perceived without any additional aids such as polarising spectacles as a spatial representation and this stereoscopically or (in the case of multi-stereograms) also auto-stereoscopically. 3 The ground glass screen master is preferably manufactured with a reflection hologram with this reflection hologram being manufactured in turn from a transmission hologram of a ground glass screen. That is, from the ground glass screen a transmission hologram is manufactured from which then the ground glass screen master is manufactured with a reflection hologram. The ground glass screen is in the form of a lenticular screen. By means of the lenticular screen, a scattering effect is achieved . From certain points, waves which are directed in a precisely defined manner are produced. An ordered or structured ground glass screen is used . As a structured pattern is provided, certain points can be predetermined and located to make adjustments. The ground glass screen master can be manufactured in at least two wavelengths, preferably in three wavelengths. By means of the fact that at least two wavelengths are used, colour effects can be generated. The use of three wavelengths is advantageous. The second master preferably contains constant information. Here, it can be an identification symbol (also known as a "logo"), preferably a three-dimensional identification symbol or a three-dimensional logo. A master hologram containing a three-dimensional logo can be recorded as a transmission hologram in a standard process. For this purpose, a three-dimensional object, that is a three-dimensional pattern of the logo, is recorded in a reflection hologram in a standard process. This hologram can then be optically replicated in a second step in that the initially manufactured first hologram is illuminated with coherent light and a second hologram generated - preferably as a reflection hologram -in the image plane. This second hologram is then the master hologram with the three-dimensional logo which can, for example, be used for a contact copy process for the manufacture of holograms. 4 It is also advantageous if the third master contains an electronically legible feature. If the above-named second master, which contains constant information, is not available, the master with the electronically legible feature naturally represents the second master. Preferably, the individual master holograms are exposed in one single overall master. This master, which contains the information of all individual masters, is then used for the manufacture of holograms. The exposure of the three masters or master holograms into one single master hologram or one single master is effected preferably one after the other in time. The master hologram generated in this manner contains the image information of the preferably three initial holograms and is the master hologram (overall master hologram) for the subsequent series production. Preferably, the three masters are recorded in two or three different wavelengths. In an apparatus for the manufacture of an individual hologram, in particular a contact copy of a hologram, with a radiation source for laser radiation, in particular laser radiation, for the irradiation of a master and a film, the object described above is solved by a modulation apparatus, in particular an LCD, for the modulation of the coherent radiation. Preferably, the master and the film are irradiated by an amplitude-modulated reference beam. The coherent radiation or the laser radiation or the amplitude-modulated reference beam contains the image information which is to be applied to the film and which should be embodied in the manufactured hologram. In the copy, two or three different wavelengths of illumination are also used - adapted to the master and their manufacturing processes. The modulation is preferably realised by an LCD (liquid crystal display). The LCD or other modulation apparatus can in turn obtain the image information by means of a computer-generated process or a scanner process or another process, for example also as a video signal. 5 The coherent radiation can be applied over the whole area to the master and the film, i.e. by radiation which exposes the whole image area at once. Preferably, the coherent radiation is, however, applied to the image area by a scanner, that is in a scanner process. The scanner serves to scan the coherent radiation over the master and the film. The scanner beam is modulated each time while passing over the image area, for example with the grey level applicable to the relevant pixel. This can be done as with a television picture, that is line by line and column by column. Mixed forms are also possible where a whole line is projected onto the image area at the same time in each case and this line then scanned in a direction perpendicular to it over the image area. Preferably, such a line scanning is used. The use of a scanner process produces advantages. Namely, for the exposure of the area covered in each case, a higher energy per surface element can be used during scanning which reduces the exposure time of this area in each case. While the total exposure time remains approximately the same, the recording is substantially less sensitive to movement here as the area covered in each case is only exposed for a shorter or a substantially shorter time. Movements of the film in relation to the master can be generated by a stress equalisation which occurs in particular in contact copying in the photographic material of the film after the clamping and lamination. Due to the higher photo-energy which is used in the scanner process and the substantial shortening of the exposure time which can be achieved thereby, movements, in particular in the photographic material of the film, can be tolerated which in an overall illumination of the image area would lead to a substantial worsening of quality. Furthermore, it is possible when a scanner process is used, to begin the exposure process after a substantially shorter time after the clamping of the film which substantially shortens the cycle time in series production. It is particularly advantageous to perform a line-by-line scanning. Here, the LCD from which the image information comes can also be scanned line by line. This information can then be passed on directly to the laser or the laser line and used for the stimulation. 6 The invention finally relates to a hologram, in particular to a contact copy of a hologram, which is manufactured in accordance with the invention with a master in accordance with the invention and/or an apparatus in accordance with the invention. It is advantageous if the hologram possesses a colour shift. For this purpose, the holograms manufactured or copied from the master can undergo a colour shift after exposure and fixing. This can above all be generated by the fixing. The colour shift has the effect that the hologram manufactured cannot be copied again by means of a contact copy with a laser of the same wavelength or that the quality of this contact copy would then be extremely poor and thus immediately recognisable as a fake. It is advantageous if during the developing and Fixing of the original hologram, it is ensured that the relevant external conditions are not identical in their spread over the surface of the hologram. Then the colour shift differs in effect due to these varying conditions if an attempt is made to make a copy and it is spread unevenly over the whole hologram copy. If, then, it is ensured that the conditions during the developing and fixing of the original hologram are not always identical on the whole carrier, the colour shift on a copy will differ topically; spots are then visible on the copy. By means of the invention, a system is provided in which multiple, preferably three masters, can be used to manufacture a hologram. The individual masters are positioned in a fixed relation to one another in the manufacture of the hologram or contact hologram. They may also overlap in full or in part. It is possible that each individual master covers the whole image area, but only contains image information in a partial area with these partial areas then, however, also being able to overlap. In the overlapping or cover areas, colour interplay or other effects can occur or be deliberately caused. It is additionally possible that the several, preferably three masters, each have a different reference angle and each have a different colour. 7 There are basically two methods available to expose the object material, that is the film, and so to generate a hologram. In accordance with a first, essentially known method the multiple or three masters are placed on top of each other. On top of these is then placed the film or the material onto which the image should be made. Then the exposure with coherent light is performed. The different masters can have different colours and/or different reference angles. In addition, the individual masters can contain different information and different types of information. For example, the first master can contain individual information. Preferably, the individual information is not generated by the master itself, but by the coherent radiation which is modulated accordingly; accordingly, the first master is preferably a ground glass screen master. The second master preferably contains a three-dimensional hologram or a three-dimensional logo. The third master preferably contains an electronically legible feature. This can also be generated in such a way that always the same master is used and that the individual electronically legible information is generated by the modulation of the coherent radiation. By means of the invention, a possibility is provided to use individual holograms with additionally constant elements, that is holograms which contain individually different information, in series production or in mass production and to use the advantageous contact copy process in doing so. In accordance with the second method, the multiple, in particular three, master holograms are exposed into one single master hologram which is then used for the manufacture of the holograms. This method has already been described above. In the system in accordance with the invention, the same master hologram can always be used for the series manufacture of holograms, in particular by means of contact copying. The individual hologram can be generated by means of the modulated illumination (preferably LCD-modulated) which interacts with the ground glass screen master part. The three-dimensional logo is always the same and is always generated in the hologram in the same way. It reacts preferably to another colour. The electronically legible feature can also be generated in interaction with a ground glass 8 screen master, that is with a modulated illumination, which can be performed in another colour. One embodiment of the invention is described below in detail by means of the enclosed drawing. In the drawing Fig. 1 shows the manufacture of a ground glass screen master; Fig. 2 shows an apparatus for the manufacture of an hologram; and Fig. 3 shows the manufacture and utilisation of a stimulation hologram. In Fig. la, the manufacture of a ground glass screen master is shown schematically. First, the ground glass screen 1 has laser light 2 irradiated through it and is recorded -as a transmission hologram - on a first hologram H1. For this purpose, a partial beam (not shown in the drawing) is coupled out of the laser beam 2 and guided at an angle of, for example, 45° as a reference beam 3 to the first hologram H1. As can be seen from Fig. lb, the ground glass screen master H2 is then manufactured from the first hologram H,. For this purpose, the image of the ground glass screen embodied in the first hologram H1 is reconstructed from said first hologram H1 as a real image. This is done by the radiation of the first hologram H1 with a laser beam 4 at an angle of 45°. The second hologram H2 is located in the image plane or in the proximity of the image plane of the first hologram H1 whereby the ground glass screen master is generated, as a reflection hologram, on said second hologram. As can be seen from Fig. lb, the second hologram H2 is exposed by an uncoupled laser beam 5 at an angle of, for example, 45°. The second hologram H2 is then the master hologram of the ground glass screen for the series production of the individual holograms. 9 Fig. 2 shows an apparatus for the manufacture of an individual hologram with a radiation source which guides laser radiation 6 onto a master H2 and onto a film 7 in contact with same positioned in the beam path in front of the master H2 and consisting of a polymer. The laser radiation 6 is modulated by a modulation apparatus (not shown in the drawing) comprising an LCD. By means of a repeated irradiation by laser beams 8 at an angle differing from the laser radiation 6, a stereo effect can be achieved. Fig. 3a shows an arrangement for using a master hologram for the manufacture of a stimulation hologram from the master holograms produced before and Fig. 3b an arrangement for using the stimulation hologram manufactured in accordance with Fig. 3a. A mask 10 with translucent regions 11 and opaque regions outside these translucent regions 11 is located on a ground glass screen 9 or a lenticular lens. Said translucent regions 11 are positioned where later hologram regions are to be created on the holographic film. The array comprising ground glass screen 9 and mask 10 is irradiated by an object beam 12 and penetrated by the radiation in the translucent regions 11. In the beam direction behind the ground glass screen 9 and the mask 10, a hologram 13 is located which is irradiated by a convergent reference beam 14. In this way, the stimulation hologram 13 is created. This stimulation hologram 13 can then be used in the manufacture of holograms. As can be seen from Fig. 3b, it is irradiated by a divergent reconstruction beam 15 whereby in the image plane, the radiation is predominantly guided into those regions where the cut-outs 11 of the mask 10 were located. As can be seen from Fig. 3, the laser beam used in the manufacture of a hologram is shaped by the stimulation hologram 13 (stimulation holograms are accordingly also known as beam shapers). By means of the stimulation hologram 13, the photo-energy is concentrated in those regions where the transmitting regions 11 of the mask 10 were 10 located. The mask 10 is generated as a real image 16 when used in accordance with Fig. 3a. Here, the array is arranged in such a way that the real image 16 of the mask 10 is created where the LCD is located which modulates the beam used in the manufacture of the hologram. As a result, the selected image regions on the modulating LCD are illuminated particularly strongly or illuminated in concentrated form which leads to a substantially higher light efficiency. While in an uncorrected process the light efficiency is only, for example, 5%, with the improved method, a light efficiency of 50% and in part up to 80% can be reached, with dichromatic methods even up to 90%. With an efficiency of 50% of the holograml3 (diffraction efficiency), 50% of the total laser power is guided into the translucent regions 11. A substantial light gain results whereby again correspondingly shorter exposure times can be achieved. -11- WE CLAIMS 1. A multiple master hologram for the copying of a hologram in a contact process, characterized in that the total master comprises preferably three individual masters which each bear different information, and the individual masters are positioned in a fixed relation to one another in the manufacture of the hologram or contact hologram. 2. A master hologram as claimed in claim 1 wherein the first master hologram is the hologram of a ground glass screen. 3. A master hologram as claimed in claim 1 wherein the ground glass screen is an ordered or structured ground glass screen in the form of a lenticular screen. 4. A master hologram as claimed in either of claims 2 or 3 wherein the ground glass screen master (H2) is manufactured with a reflection hologram (H1) which is manufactured from a transmission hologram of a ground glass screen (1). 5. A master hologram as claimed in any of claims 2 to 4 wherein the ground glass screen master (H2) is manufactured in at least two wavelengths, preferably in three wavelengths. 6. A master hologram as claimed in any of the preceding claims wherein the second master contains constant information, preferably an identification symbol, preferably a three-dimensional identification symbol. 6. -12- 7. A master hologram as claimed in any of the preceding claims wherein the third master contains an electronically legible feature. 8. A master hologram as claimed in any of the preceding claims wherein the individual masters are exposed into one signle master. 9. A master hologram as claimed in any of the preceding claims wherein stimulation holograms are manufactured from the master(s). 10. A master hologram as claimed in claim 9 wherein the stimulation hologram is manufactured as a computer-generated hologram ( CGH). 11. A master hologram as claimed in claim 9 wherein the stimulation hologram is manufactured interferometrically. 12. An apparatus for the manufacture of an individual hologram, in particular of a contact copy of the hologram (7), with : - a radiation source for laser irradiation (6,8) of the irradiation of a master hologram (H2) in accordance with one of the claims 1 to 11 and a film (7). - and a modulation apparatus, in particular an LCD, for the modulation of the coherent radiation (6,8). -13- 13. An apparatus as claimed in claim 12 wherein the master (H) is irradiated with several, preferably two or three different wavelengths, 14. An apparatus as claimed in either of claims 12 or 13 wherein a scanner is provided for the scanning of the coherent radiation over the master and the film. 15. An apparatus as claimed in any of claims 12 to 14 wherein a stimulation hologram (13) is to shapes the coherent radiation. 16. An apparatus as claimed in claim 15 wherein the stimulation halogram is a computer-generated hologram (CGH). 17. An apparatus as claimed in claim 15 wherein the stimulation hologram (13) is manufactured interferometrically. 18. An apparatus as claimed in any of claims 12 to 17 wherein a colour apparatus is provided far the colour irridatian of the master and the film, in particular an LCD with colour capability. 19. An apparatus as claimed in any of claims 12 to 18 wherein an apparatus for the exposure of different aspect angles. Dated this 31st day of JULY, 1998 This invention relates to a multiple master hologram for the copying of a hologram in a contact process, characterized in that the total master comprises preferably three individual masters which each bear different information, and the individual masters are positioned in a fixed relation to one another in the manufacture of the hologram or contact hologram,

Documents:

01352-cal-1998-abstract.pdf

01352-cal-1998-assignment.pdf

01352-cal-1998-claims.pdf

01352-cal-1998-correspondence.pdf

01352-cal-1998-description(complete).pdf

01352-cal-1998-drawings.pdf

01352-cal-1998-form-1.pdf

01352-cal-1998-form-2.pdf

01352-cal-1998-form-26.pdf

01352-cal-1998-form-3.pdf

01352-cal-1998-form-5.pdf

01352-cal-1998-priority document(others).pdf

01352-cal-1998-priority document.pdf

1352-cal-1998-granted-abstract.pdf

1352-cal-1998-granted-claims.pdf

1352-cal-1998-granted-correspondence.pdf

1352-cal-1998-granted-description (complete).pdf

1352-cal-1998-granted-drawings.pdf

1352-cal-1998-granted-examination report.pdf

1352-cal-1998-granted-form 2.pdf

1352-cal-1998-granted-letter patent.pdf

1352-cal-1998-granted-priority document.pdf

1352-cal-1998-granted-reply to examination report.pdf

1352-cal-1998-granted-specification.pdf

1352-cal-1998-granted-translated copy of priority document.pdf