RU200167U1 - A device for recording microholograms with a latent coded image for personalizing replicated photopolymer security holograms - Google Patents

Abstract

The utility model relates to holographic systems for recording digital information and can be used to personalize security holograms in the process of their continuous replication on photopolymer materials. The technical result of improving the prototype recording device while maintaining the required image quality of the MGF CC in protective holograms is provided by: - replacing the laser radiation source in the prototype device with an LED one, - using a role mechanism for winding up the photopolymer film carrier instead of a linear movement system and a rotary mechanism for rotating the recording medium , - additional installation of a position sensor for personalized security holograms and an electronic unit for synchronizing the operation of a LED emitter operating in a pulsed mode, a position sensor for personalized security holograms and a PMS that forms a MGF for recording into security holograms. A device for recording microholograms with a latent coded image for personalizing replicated photopolymer security holograms contains a radiation source, optical elements for expanding the radiation beam, an electronic unit for computer synthesis of Fourier microholograms, a matrix spatial light modulator (PMS) for inputting Fourier microholograms synthesized in an electronic unit into an optical channel, a projection optical system with a diaphragm that provides cutoff of radiation in non-informative diffraction orders, for transferring an image from the SLM plane to the plane of a photosensitive recording medium, which is a thin-film photopolymer material, and a device for moving the recording medium. In this case, a pulsed LED emitter controlled by a sync pulse generator is used as a radiation source. The device additionally contains an optical sensor for the position of personalized security holograms on a continuously movable strip of thin-film photopolymer material as a recording medium and an electronic unit for synchronizing the operation of a pulsed LED emitter, a position sensor for personalized security holograms on a continuously movable strip of material, and a PMS that forms a MGF for recording into security holograms. As a device for continuous movement of the strip of material, a roll mechanism is used for rewinding and unwinding the material. The entire device can be installed in a single common light-shielding housing. 1 ill.

Description

Technology area

The utility model relates to holographic systems for recording digital information and can be used to personalize security holograms during their replication on photopolymer materials.

State of the art

The modern development of technologies in security printing provides for the use of security elements in identification documents, banknotes, excise stamps and other products based, among other things, on volume-phase holograms, the replication of which not so long ago seemed to be a complex technological and materials science task.

For accounting and control systems of hologram carriers, continuous numbering or coding is usually used. An individual number is printed on the security holograms after their replication, and thus, these holograms become personalized. Currently, personalization methods such as dot perforation or printing with a ribbon are widely used, while in both cases, the applied individual numbers take a significant part of the useful area of the security hologram. In addition, individual numbers obtained by printing are located on the surface of the hologram and can be intentionally or accidentally erased, which will lead to problems in accounting and control of protected products.

To solve these problems, it is proposed to individualize photopolymer security holograms by recording latent encoded images in the form of Fourier micro-holograms (MHF) up to 2 × 2 mm ^{2 in} size. Coding is used to compress the recorded useful information, allowing you to place personal digital information of almost any complexity in one MGF, and to achieve a stable machine-readable recovery of a sufficiently large amount of data (up to 1 MB). Personal information recorded in the IHF can be a serial number changeable by i + 1 increments for each individual security hologram, information about the manufacturer, logos, rules for the use of products or drugs, advertising videos, etc. The advantages of this personalization method in comparison with perforation, printing Ribbon, etc. is a significantly larger information capacity with a smaller area allotted for personalization, no violation of the integrity of the carrier material and resistance to erasure of information. To implement this method, it is required to develop a corresponding optoelectronic device that records an additional sub-hologram with individual information of hidden coded images in the form of MGF in the required local place of the main security hologram. With such a MGF, a latent coded image can be restored and then registered by a photodetector, with subsequent decoding of the input digital information and its identification in the form of individual digital information of almost any complexity.

Known devices for recording computer-synthesized Fourier holograms (CS GF) on a recording medium by outputting the calculated structure of the synthesized hologram to a matrix device and subsequent projection of the image with the required reduction onto the recording medium at a perpendicular position of the recording medium relative to the axis of the light beam. One of these devices is described in RF patent No. 162199 (IPC G11B 7/0065, G03H 1/08, publ. 05/27/2016) "A device for recording computer-synthesized multiplex Fourier holograms in an optical-holographic memory system." In this device, the radiation source is an incoherent light-emitting diode, which avoids the influence of speckle noise, which is inevitably present on the surface of the recording medium under coherent illumination. The use of incoherent radiation reduces the likelihood of errors in reading information. This device uses a reflective matrix spatial light modulator (SLM) and a polarization cube to reduce the length of the circuit, but at the same time the overall dimensions of the device are increased in width.

In the case of applying this device to the task of personalizing thin-film photopolymer security holograms in the process of their replication, its limitation is the lack of functionality in the form of role mechanisms for rewinding and rewinding the film photopolymer recording medium. In addition, the use of a reflective SLM in combination with a polarizing beam-splitting cube leads to a greater loss of radiation power than when using a single SLM operating in transmission.

As the closest analogue (prototype), you can take a hologram recording device according to RF patent No. 123184 (IPC G03H 1/08, publ. 20.12.2012) "Device for recording multiplex holograms in an optical holographic memory system". The recording device consists of an illumination optical system, including a laser radiation source, an objective, a diaphragm for optical filtering of the source radiation, and a collimating lens, as well as a transmissive matrix PMS for entering the GF CC and a projection optical system including the first lens, a diaphragm for filtration higher orders of diffraction of the spectrum of the hologram, caused by the discrete structure of the matrix device, and the second objective in front of the recording medium, located perpendicular to the optical axis of the recording device.

The technical limitations of this device as applied to the personalization of security holograms in the process of their continuous replication should include the use of a laser emitter, which leads to a speckle noise distortion of the GF CC output to the PMS, as well as the absence of a role mechanism for rewinding and rewinding the film photopolymer carrier of security holograms.

Disclosure of a utility model

The technical result of the proposed utility model is the improvement of a prototype device for recording multiplex holograms in an optical holographic memory system for recording personalized hidden coded images in the form of computer synthesized Fourier microholograms (CS MGF) into continuously replicated security holograms on a thin-film photopolymer carrier.

The technical result, while maintaining the required image quality of the MGF CC in protective holograms, is provided by: - replacing the laser radiation source as part of the prototype device with an LED one, - using a role mechanism for winding up a film photopolymer carrier instead of a linear movement system and a rotary mechanism for rotating the recording medium, - an additional installation a position sensor for personalized security holograms and an electronic unit for synchronizing the operation of a LED emitter operating in a pulsed mode, a position sensor for personalized security holograms and a PMS that forms a MGF for recording into security holograms.

Thus, the device for recording microholograms with a latent coded image for personalizing replicated photopolymer security holograms contains a radiation source, optical elements for expanding the radiation beam, an electronic unit for computer synthesis of Fourier microholograms, a matrix spatial light modulator (LMS) for inputting Fourier microholograms synthesized in an electronic unit into an optical channel, a projection optical system with a diaphragm that cuts off radiation in non-informative diffraction orders, for transferring an image from the SLM plane to the plane of a photosensitive recording medium, which is a thin-film photopolymer material, and a device for moving the recording medium. In this case, a pulsed LED emitter controlled by a sync pulse generator is used as a radiation source. The device additionally contains an optical sensor for the position of personalized security holograms on a continuously movable strip of thin-film photopolymer material as a recording medium and an electronic unit for synchronizing the operation of a pulsed LED emitter, a position sensor for personalized security holograms on a continuously movable strip of material, and a PMS that forms a MGF for recording into security holograms. As a device for continuous movement of the strip of material, a roll mechanism is used for rewinding and unwinding the material. The entire device can be installed in a single common light-shielding housing.

Figure 1 shows a functional diagram of the device.

Implementation of the utility model

The device (figure 1) consists of a sync pulse generator 1 for an incoherent emitter, which is used as a pulsed LED radiation source 2, optical elements 3 and 4 for expanding the radiation beam of a source 2, an electronic unit 5 for computer synthesis of Fourier microholograms, a matrix spatial light modulator 6 for inputting information of computer-synthesized Fourier microholograms (CS MGF) from block 5 into the optical system, a projection optical system consisting of optical components 7, 9, and 10 and aperture 8, for projecting an image of the CS MGF from the plane of the modulator into the plane of the photosensitive recording medium representing is a strip of thin-film photopolymer material 11, continuously moved by the roller mechanism 13 for rewinding and rewinding the strip, an optical position sensor 14 of personalized security holograms on the strip of material, an electronic driver 12 that controls the role-playing mechanism 13, and an electronic bl oka synchronization 15 operation of generator 1 for source 2, electronic unit KS MGF 5 for PMS 6, electronic driver 12 of mechanism 13 and optical position sensor 14 holograms on strip 11. The entire device can be installed in a single common light-shielding housing (not shown in the diagram) ...

The device works as follows. By a command coming from the electronic synchronization unit 15, the sync pulse generator 1 turns on or off the LED radiation source 2. The radiation of the LED operating in a pulsed mode passes through optical elements 3 and 4, with the help of which the diameter increases and the radiation beam collimates to illuminate the aperture PMS 6. Electronic unit 5 is used for computer synthesis of Fourier microholograms H _i . The output to the PMS 6 of each subsequent MGF COP with personal information and an individual number is carried out by the electronic unit 5 on command from the synchronization unit 15. The image of the MGF COP formed on the PMS aperture is transferred to a continuously moving strip with a thin-film photopolymer recording medium 11 with security holograms already recorded up to this point. Aperture 8, installed in the rear focal plane of lens 6, eliminates the results of light scattering in the optical path from lenses 7, 9 and 10. The synthesized structure of the interference pattern is a two-dimensional diffraction structure, and when restoring an image from a hologram with such a diffractive structure, the image appears twice, namely in +1 and -1 diffraction orders. One of these orders is parasitic. Diaphragm 8 also serves to eliminate it. The recording medium 11 is fed into the recording area of personalized MGFs and is rolled into a roll for storage in a continuous mode using a role mechanism 13, which is controlled by an electronic driver 12 in accordance with the commands of the synchronization unit 15. Since personalization of protective holograms are produced in the mode of continuous supply of thin-film photopolymer recording medium 11, and the position of the areas for recording individual MGFs on the frames of personalized holograms on the strip of thin-film photopolymer recording medium 11 should be the same, then to determine the moments of exposure and generate the corresponding light pulses, an optical position sensor 14 of personalized security holograms, coupled with the electronic synchronization unit 15. At the moment of approaching the position sensor 14 of the reference mark of each subsequent personalized hologram recorded on the photopolymer th film 11, from the sensor 14 a signal is sent to the synchronization unit 15, which, in turn, sends sync pulses to the generator 1 of the LED 2 and the electronic unit 5 for output to the SLM 6 of the corresponding MGF H _i . This does not stop the role-playing mechanism 13 and the supply of the thin-film photopolymer strip 11 is carried out continuously until the completion of the personalization process of the circulation of the security holograms.

An approximate estimate of the permissible duration of the pulse recording the MGF per frame of the main hologram, already recorded before that on a continuously moving thin-film photopolymer strip with a movement speed of up to 2 cm / s. The permissible error in changing the position of the MGF on the frame of the main hologram can be approximately 0.01 μm. The permissible duration of the pulse for recording the MGF is obtained by dividing the permissible error in the position of the MGF by the speed of the strip movement, which will ultimately be 0.5 μs or 500 ns. For this duration it is necessary to choose the speed of the optoelectronic components of the device and the speed of synchronization of their interaction.

The implementation of the proposed utility model will allow individualization of each individual hologram in the process of continuous replication, in which the integrity of the main hologram on a photopolymer carrier is not violated, as happens in the case of additional perforation, and the useful area of the main hologram is practically not taken away, as in the case of applying to it additional printing prints.

Claims (1)

A device for recording microholograms with a latent coded image for personalizing replicated security holograms on a photopolymer carrier, containing a radiation source, optical elements for increasing the diameter and collimating the radiation beam, an electronic unit for computer synthesis of Fourier microholograms (MGF), a matrix spatial light modulator (SPM) for computer input synthesized Fourier microholograms into the optical channel, a projection optical system with a diaphragm that provides cutoff of radiation in non-informative diffraction orders for transferring an image from the SLM plane to the registration plane, a photosensitive recording medium in the image formation region of the modulator aperture and a device for moving the recording medium, characterized in that a pulsed LED emitter controlled by a sync pulse generator was used as a radiation source; the device additionally contains an optical sensor for the position of personalized security holograms on a continuously movable strip of thin-film photopolymer material as a recording medium and an electronic unit for synchronizing the operation of a pulsed LED emitter, a position sensor for personalized security holograms on a continuously movable strip of material and a PMS that forms a MGF for recording into security holograms; As a device for continuous movement of a strip of material, a roll mechanism is used for rewinding and unwinding the material.

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