rus
Issue #1/2016
S.Odinokov, I.Tsyganov, V.Talalaev, N.Piryutin, V.Kolyuchkin, E.Zlokazov
Scanner for Automatic Control of Security Holograms Authenticity on Passport Documents
Scanner for Automatic Control of Security Holograms Authenticity on Passport Documents
The optoelectronic scanner for operational control of authenticity of security holograms on passport documents, which allows determining one of the main characteristic features of security holograms and identifying the security hologram in automatic mode with high level of probability within minimum period of time, is considered.
Document protection against the mass falsification is one of the most serious problems occurring before the world economy and governmental organizations of all developed countries. According to the data of International Hologram Manufacturers Association (IHMA), the total amount of losses due to the document counterfeiting and falsification of the commodities of the best known trademarks and brands was more than 100 billion US dollars in 2013. Paper and plastic documents are the most vulnerable items to falsification [1–2].
Today security holograms are used for the document protection against falsification all over the world. In Russia as well as in many foreign countries, security holograms (SH) are actively used for the marking of different documents, such as passports of citizens and identity cards; permits of the officers of special governmental organizations and institutions; licenses, patents; documents on education and qualification, bank securities and bank plastic cards; excise marks of alcoholic products and many other documents. Also at the present time, the task of verification of driver’s licenses is very urgent due to the events of their falsification, which have become more frequent.
In the course of the visual observations, the control of SH authenticity is performed by the eyes of inspector on the basis of visible holographic images. In such case, conditions of SH observation and subjective human abilities connected with the perception and interpretation of received information have great impact on making the final decision; the identification duration can last for units to several tens of minutes, and this fact does not meet the practical requirements of the control of SH authenticity in real time [1–2].
Thus, the mass production of SHs and their particular significance for the protection of documents against falsification result in the urgency of the task of identification and control of SH authentication with the assistance of automatic optoelectronic instruments and devices on a real time basis.
Security holograms represent the set of multitude of diffraction gratings having various characteristics, such as period (spatial frequency) of diffraction grating, its orientation in the hologram plane, height and shape of the profile for relief-phase holograms.
Proposed optoelectronic scanner for operational control of authenticity of security holograms on the passport documents allows determining one of the main characteristic features of security holograms making it possible to identify the security hologram in automatic mode with high level of probability within minimum period of time.
Such features include the spatial-frequency spectrum (SFS) of security hologram obtained during its irradiation with coherent radiation. Depending on the characteristics of gratings, it is possible to record SFS of certain zones on SH and compare it with the SFS of reference SH for the operation of hologram identification. SH identification is based on the fact that SFS of each zone is unique. Establishment of optimal conditions of SH illumination with laser radiation, such as illumination direction and corresponding detection direction, wavelengths of probing laser radiation, shape of probing beam of laser radiation becomes the determining factor when solving the set task. Also, when solving the task of SH identification on the basis of its SFS the algorithm of SFS identification from investigated hologram refers to the important aspect in order to compare it with the SFS of reference SH. In order to solve this task, the most convenient action consists in the use of correlation algorithms of processing of signals and images with the creation of correlation filters allowing the significant reduction of the requirements to the positioning of investigated SH relative to the optical system of control channel.
Structurally, the optoelectronic scanner for operational control of authenticity of security holograms on passport documents (hereinafter, OE scanner or device) represents the rectangular framework with support assembly, which can be capped (Fig. 1 and Fig. 2). The support assembly corresponds to the glass supporting structure in the upper part of the device, on which the controlled document is located. The optical head, which can be moved in longitudinal direction inside the device providing the linear scanning, is located inside the framework on two cylindrical guides. The movement of optical head is performed with the use of ball screw, and in this respect the screw is actuated with the assistance of belt transmission from the stepping motor.
The optical head contains the targeting channel and identification system consisting of four channels. The visual targeting channel is intended for the device positioning relative to the investigated document. The visual channel consists of the illumination system including six light emitting diodes with white color and radiation detector array. The identification system contains 4 analogous optical recording channels. Each recording channel uses four laser diodes (LD) in the capacity of radiation sources with the wavelengths of 0.405, 0.532, 0.65, 0.85 мm and radiation power of 5 mW to 20 mW. Radiation from all laser diodes passing through the collimator gets on the surface of controlled document. In order to visualize the spatial-frequency spectrums obtained as the result of diffraction phenomenon on SH of controlled document, the device uses optical visualizer [3–4]. Image received from the visualizer is recorded by the radiation detector array. All components of optical head are rigidly fixed in the metal structure. Design of the device provides the optical sensors for motion restriction of optical head.
Electronic modules of power supply control, operation of stepping motor, laser diodes, light emitting diodes, radiation detector arrays and operation of indication of the device current status based on built-in liquid crystal display are arranged in the device case. Operator control of the unit – buttons S1 "On/Off", S2 "Option Up", S3 "Start of Investigation/Initialization" is located under the display.
In order for the unit to function, a computer with specialized software is required. The computer implements the algorithm of control of document authenticity on the basis of SH spatial-frequency spectrums of controlled document and produces the control signals of unit components.
Figure 3 contains the photograph of OE scanner appearance with the information concerning the control session on the monitor of supervisory computer; also, Table gives technical data of the unit.
The works are performed at Bauman Moscow State Technical University with financial support from the Ministry of Education and Science of Russia within the framework of execution of the project part of governmental task (project No. 3.1426.2014K).
Today security holograms are used for the document protection against falsification all over the world. In Russia as well as in many foreign countries, security holograms (SH) are actively used for the marking of different documents, such as passports of citizens and identity cards; permits of the officers of special governmental organizations and institutions; licenses, patents; documents on education and qualification, bank securities and bank plastic cards; excise marks of alcoholic products and many other documents. Also at the present time, the task of verification of driver’s licenses is very urgent due to the events of their falsification, which have become more frequent.
In the course of the visual observations, the control of SH authenticity is performed by the eyes of inspector on the basis of visible holographic images. In such case, conditions of SH observation and subjective human abilities connected with the perception and interpretation of received information have great impact on making the final decision; the identification duration can last for units to several tens of minutes, and this fact does not meet the practical requirements of the control of SH authenticity in real time [1–2].
Thus, the mass production of SHs and their particular significance for the protection of documents against falsification result in the urgency of the task of identification and control of SH authentication with the assistance of automatic optoelectronic instruments and devices on a real time basis.
Security holograms represent the set of multitude of diffraction gratings having various characteristics, such as period (spatial frequency) of diffraction grating, its orientation in the hologram plane, height and shape of the profile for relief-phase holograms.
Proposed optoelectronic scanner for operational control of authenticity of security holograms on the passport documents allows determining one of the main characteristic features of security holograms making it possible to identify the security hologram in automatic mode with high level of probability within minimum period of time.
Such features include the spatial-frequency spectrum (SFS) of security hologram obtained during its irradiation with coherent radiation. Depending on the characteristics of gratings, it is possible to record SFS of certain zones on SH and compare it with the SFS of reference SH for the operation of hologram identification. SH identification is based on the fact that SFS of each zone is unique. Establishment of optimal conditions of SH illumination with laser radiation, such as illumination direction and corresponding detection direction, wavelengths of probing laser radiation, shape of probing beam of laser radiation becomes the determining factor when solving the set task. Also, when solving the task of SH identification on the basis of its SFS the algorithm of SFS identification from investigated hologram refers to the important aspect in order to compare it with the SFS of reference SH. In order to solve this task, the most convenient action consists in the use of correlation algorithms of processing of signals and images with the creation of correlation filters allowing the significant reduction of the requirements to the positioning of investigated SH relative to the optical system of control channel.
Structurally, the optoelectronic scanner for operational control of authenticity of security holograms on passport documents (hereinafter, OE scanner or device) represents the rectangular framework with support assembly, which can be capped (Fig. 1 and Fig. 2). The support assembly corresponds to the glass supporting structure in the upper part of the device, on which the controlled document is located. The optical head, which can be moved in longitudinal direction inside the device providing the linear scanning, is located inside the framework on two cylindrical guides. The movement of optical head is performed with the use of ball screw, and in this respect the screw is actuated with the assistance of belt transmission from the stepping motor.
The optical head contains the targeting channel and identification system consisting of four channels. The visual targeting channel is intended for the device positioning relative to the investigated document. The visual channel consists of the illumination system including six light emitting diodes with white color and radiation detector array. The identification system contains 4 analogous optical recording channels. Each recording channel uses four laser diodes (LD) in the capacity of radiation sources with the wavelengths of 0.405, 0.532, 0.65, 0.85 мm and radiation power of 5 mW to 20 mW. Radiation from all laser diodes passing through the collimator gets on the surface of controlled document. In order to visualize the spatial-frequency spectrums obtained as the result of diffraction phenomenon on SH of controlled document, the device uses optical visualizer [3–4]. Image received from the visualizer is recorded by the radiation detector array. All components of optical head are rigidly fixed in the metal structure. Design of the device provides the optical sensors for motion restriction of optical head.
Electronic modules of power supply control, operation of stepping motor, laser diodes, light emitting diodes, radiation detector arrays and operation of indication of the device current status based on built-in liquid crystal display are arranged in the device case. Operator control of the unit – buttons S1 "On/Off", S2 "Option Up", S3 "Start of Investigation/Initialization" is located under the display.
In order for the unit to function, a computer with specialized software is required. The computer implements the algorithm of control of document authenticity on the basis of SH spatial-frequency spectrums of controlled document and produces the control signals of unit components.
Figure 3 contains the photograph of OE scanner appearance with the information concerning the control session on the monitor of supervisory computer; also, Table gives technical data of the unit.
The works are performed at Bauman Moscow State Technical University with financial support from the Ministry of Education and Science of Russia within the framework of execution of the project part of governmental task (project No. 3.1426.2014K).
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