A polarizing film printer

Abstract

The present application belongs to the technical field of information security, and more particularly relates to a polarization film printer. Linearly polarized light is output by an externally modulated pulsed fiber laser, and a special laser head is used to realize polarization encoding printing on a special carrier on a sample table through a high-precision two-dimensional linear displacement platform. A pulsed fiber laser is used to output linearly polarized light. The output light is connected to a Faraday magneto-optical tube through a polarization maintaining optical fiber to control the polarization state. Then, the Faraday magneto-optical tube is connected to another polarization maintaining optical fiber to guide the light to a special printing laser head. The special printing laser head can realize polarization encoding printing on a special carrier on the sample table under the assistance of a high-precision two-dimensional linear displacement platform and the regulation of an external computer.

Description

Technical Field

[0001] This invention belongs to the field of information security technology, and more specifically relates to a polarization film printer. It uses an externally modulated pulsed fiber laser to output linearly polarized light, which is then transmitted through a specially designed laser head led out of an optical fiber. This laser head then passes through a high-precision two-dimensional linear displacement platform to print polarization-encoded images onto a specially designed carrier on a sample stage. It can be used in national defense and security fields such as secure communication and information concealment. Background Technology

[0002] Polarization printing technology is one of the emerging core technologies in the field of secure communication. With today's advanced communication technology, electromagnetic interception and anti-interception technologies are quite mature. How to achieve highly secure information transmission has attracted widespread attention.

[0003] To achieve highly secure information transmission in the current environment, it is essential to transmit information using non-electromagnetic media. However, most existing information encryption technologies cannot circumvent the critical issue of electromagnetic wave shielding. Visual encryption-based information storage technology utilizes non-electromagnetic media such as film and paper for encrypted information storage. Decryption is only possible after all the stored encrypted media are collected; the loss of any one media renders the decrypted information meaningless gibberish. This effectively solves the problem of interception of non-electromagnetic encrypted media. However, existing visual encryption-based information storage technologies suffer from limited transmission capacity and complex encryption / decryption processes. High-fidelity encryption and decryption technology based on polarization XOR operations enables encryption and decryption under incoherent light conditions, significantly increasing the transmission capacity of encrypted information. Furthermore, the encrypted media produced by this technology are spatially aligned, allowing for decryption by visual inspection, greatly reducing the difficulty of decryption. However, because the fabrication of the encrypted media requires laser thermally induced depolarization technology, existing laser marking machines cannot efficiently and quickly process double-sided orthogonally polarized composite polarization films, making the high-fidelity encryption and decryption technology based on polarization XOR operations still relatively complex in the encryption process. Only by solving the problem of the complexity of producing encrypted carriers can this encryption technology be expected to achieve practical application in the future. Summary of the Invention

[0004] To address the problem that existing laser marking machines cannot efficiently and quickly process double-sided orthogonally polarized composite polarizing films, this invention proposes a polarizing film printer.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A polarization film printer includes a fiber laser, a Faraday magnetostrictive radiator, a first polarization-maintaining fiber, a second polarization-maintaining fiber, a specialized printing laser head, and a high-precision two-dimensional linear displacement platform. The fiber laser is connected to the Faraday magnetostrictive radiator via the first polarization-maintaining fiber. The Faraday magnetostrictive radiator is connected to the specialized printing laser head via the second polarization-maintaining fiber. The specialized printing laser head is mounted on the high-precision two-dimensional linear displacement platform. The pulsed fiber laser outputs polarized light, which is connected to the Faraday magnetostrictive radiator via the first polarization-maintaining fiber to control the polarization state. The Faraday magnetostrictive radiator then guides the light to the specialized printing laser head via the second polarization-maintaining fiber. With the assistance of the high-precision two-dimensional linear displacement platform and the control of an external computer, the specialized printing laser head can perform polarization-encoded printing on a specially designed encrypted carrier on a sample stage.

[0007] In a further optimization of this technical solution, the fiber laser is a single-polarization pulse fiber laser.

[0008] This technical solution is further optimized by including a special printing laser head comprising an optical system consisting of a beam shaper and an electrically controlled displacement lens group.

[0009] In a further optimization of this technical solution, the specially designed printing laser head includes a beam shaper and an electrically controlled displacement lens group connected in sequence. The light enters the beam shaper, which shapes the Gaussian beam output from the second polarization-maintaining fiber into a flat-top beam. The shaped light then passes through an electrically controlled displacement lens group controlled by an electrically controlled linear displacement stage. By changing the relative positions of the lenses in the lens group, the magnification of the lens group can be controlled to output a square light spot of a suitable size on the light output plane, so as to meet the requirements of the target pixel size.

[0010] In a further optimization of this technical solution, the tail end of the second polarization-maintaining fiber connecting the specially designed printing laser head is provided with a gold-plated square window on the fiber cross-section, which is used to shape the circular light spot into a pixelated square light spot.

[0011] In a further optimization of this technical solution, the encrypted carrier is a double-sided orthogonally polarized composite polarization film. Specifically, two layers of PVA film with adsorbed iodine molecules are placed on both sides of a polyvinyl alcohol resin film substrate and stretched in an oriented manner. The iodine molecules of the two PVA films are arranged perpendicularly to each other, so that the two sides of the transparent film have different dichroisms. In this way, lasers with different polarization directions can selectively cut and process the upper or lower surface.

[0012] The above technical solution has the following advantages, unlike existing technologies:

[0013] 1. This invention utilizes a Faraday magneto-optical rotator to control the polarization direction of the output light, thus solving the problem of uncontrollable polarization direction of the output light in traditional laser marking machines.

[0014] 2. This invention uses a specially designed laser head to achieve beam shaping, which effectively solves the problem of uncontrollable output spot size and shape of traditional laser marking machines.

[0015] 3. This invention uses specific polarized light to precisely and specifically process both sides of the double-sided orthogonally polarized composite polarization film, realizing the efficient and rapid production of encrypted carriers based on polarization XOR operation for high-fidelity encryption and decryption. Attached Figure Description

[0016] Figure 1 This is a diagram showing the overall structure of a polarization printer.

[0017] Figure 2 Diagram of the internal structure of a specially designed laser head;

[0018] Figure 3 This is a diagram showing the potential control of a Faraday magnetopolaris tube.

[0019] Figure 4 This is a schematic diagram of laser thermally induced depolarization.

[0020] Figure 5 This is a schematic diagram illustrating the principle of polarization switching.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1: Fiber laser; 2: Faraday magnetopolarimeter; 3: Second polarization-maintaining fiber; 4: Specially designed printing laser head.

[0023] 5: High-precision two-dimensional linear displacement platform; 6: External computer connection.

[0024] 41: Light output port; 42: Electrically controlled shift lens group; 43: Beam shaper

[0025] 44: Fiber optic inlet; 45: Gold-plated square window of fiber optic cross-section. Detailed Implementation

[0026] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0027] Please see Figure 1 The diagram shows the overall structure of a polarization printer. A preferred embodiment of this invention is a polarization film printer. An externally modulated pulsed fiber laser 1 outputs linearly polarized light. The output light is connected to a Faraday magnetostrictive radiator 2 via a first polarization-maintaining fiber to control the polarization state. The Faraday magnetostrictive radiator 2 is then connected to a second polarization-maintaining fiber 3 to guide the light to a specially designed printing laser head 4. With the assistance of a high-precision two-dimensional linear displacement platform 5 and the control of an external computer 6, the specially designed printing laser head 4 can perform polarization-encoded printing on a specially designed encrypted carrier on a sample stage.

[0028] In this embodiment, the fiber laser 1 is a single-polarization pulse fiber laser. It outputs polarized light through a first polarization-maintaining fiber and then connects to a Faraday magnetopolaris tube 2 device. By applying voltage, the polarization direction of the output laser can be switched between the P and S directions.

[0029] The Faraday magnetostrictive rotator 2 utilizes the Faraday magnetostrictive effect. By applying a controllable magnetic field parallel to the light propagation medium, the input voltage of the Faraday magnetostrictive rotator 2 can be changed to achieve quantifiable control of the rotation angle of the light polarization direction. Rotating the output light polarization direction by 90° allows for switching the selection of the processing surface for the double-sided orthogonally polarized composite polarizing film.

[0030] See Figure 2 The diagram shows the internal structure of the specially designed laser head. The specially designed printing laser head 4 includes an optical system consisting of a beam shaper and an electrically controlled displacement lens group, which can adjust the output laser shape and the size of the printed pixels. The input light enters the beam shaper 43 at the front end through the fiber optic inlet 44, shaping the Gaussian beam output from the second polarization-maintaining fiber 3 into a flat-top beam suitable for laser processing. The shaped light then passes through the electrically controlled displacement lens group 42, which is controlled by an electrically controlled linear displacement stage. By changing the relative positions of the lenses in the lens group, the magnification of the lens group can be controlled to output a square spot of appropriate size on the output plane, meeting the requirements of the target pixel size. The shaped spot is then perpendicularly irradiated onto a high-precision two-dimensional linear displacement platform through the output port 41, completing the beam processing that meets the printing conditions.

[0031] A beam shaper is inserted into the lens group to shape the Gaussian spot into a flat-top beam. At the same time, the entire electrically controlled displacement lens group is mounted on a linear electrically controlled displacement platform to adjust the size of the printed pixels.

[0032] The aperture is a gold-plated square window 45 on the cross section of the tail fiber of the specially designed polarization-maintaining fiber of the laser head, which is used to shape the circular light spot into a pixelated square light spot.

[0033] The encrypted carrier is a double-sided orthogonally polarized composite polarizing film. Specifically, it consists of two layers of PVA film, each adsorbed with iodine molecules and stretched in a specific direction, placed on either side of a polyvinyl alcohol (PVA) resin film substrate. The iodine molecules in the two PVA films are arranged perpendicularly to each other, resulting in different dichroisms on both sides of the transparent film. This allows lasers with different polarization directions to selectively cut and process either the upper or lower surface. The double-sided orthogonally polarized composite polarizing film allows for selective processing of its upper or lower surface using lasers with different polarization directions. The processing method described is a laser-induced depolarization effect.

[0034] Polarization-encoded printing employs a laser-induced depolarization processing mechanism. A high-precision two-dimensional linear displacement platform 5, controlled by an external computer program 6, can precisely control a specially designed printing laser head, achieving rapid positioning. Subsequently, the computer controls the potential of the Faraday magnetostrictive tube to precisely control the polarization state of the output light, thus achieving in-situ polarization-encoded printing with polarization switching. Here, the laser output is set to P-polarized light when no voltage is applied, and S-polarized light when voltage is applied. The potential control diagram corresponding to the ciphertext encoding principle is as follows: Figure 3 As shown. These two work together to automate the encoding and printing of the encrypted carrier.

[0035] See Figure 4 The diagram illustrates laser-induced depolarization. When a laser continuously irradiates the surface of a polarizing film, the dichroic iodine molecules arranged in an orderly fashion within the film generate a thermal effect as they continuously absorb the laser light. This causes the iodine molecules adsorbed on the polarizing film to volatilize, resulting in the polarizing film losing its dichroic absorption function—a process known as depolarization. After depolarization, the transmittance of the carrier for polarized light in all directions is consistent; this is the principle behind laser-induced depolarization.

[0036] See Figure 5 The diagram illustrates the polarization switching principle. When the specially designed printing laser head 4 outputs laser light with a polarization direction parallel to the transmission axis of the upper surface of the double-sided orthogonally polarized composite polarization film, the upper surface completely absorbs this polarized light, leading to thermally induced depolarization. When the polarization direction of the laser head is rotated 90°, the laser polarization direction becomes parallel to the transmission axis of the upper surface, allowing the laser to completely pass through the upper surface and the intermediate film before being completely absorbed by the lower surface, resulting in depolarization. This achieves in-situ polarization coding printing technology with polarization switching.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising..." or "including..." does not exclude the presence of additional elements in the process, method, article, or terminal device that includes said element. Additionally, in this document, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number.

[0038] Although the above embodiments have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the above descriptions are merely embodiments of the present invention and do not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A polarizing film printer, characterized in that, It includes a fiber laser, a Faraday magnetostrictive radiator, a first polarization-maintaining fiber, a second polarization-maintaining fiber, a specially designed printing laser head, and a high-precision two-dimensional linear displacement platform. The fiber laser is connected to the Faraday magnetostrictive radiator via the first polarization-maintaining fiber. The Faraday magnetostrictive radiator is connected to the specially designed printing laser head via the second polarization-maintaining fiber. The specially designed printing laser head is mounted on the high-precision two-dimensional linear displacement platform. The fiber laser outputs polarized light, which is connected to the Faraday magnetostrictive radiator via the first polarization-maintaining fiber to control the polarization state. Then, the Faraday magnetostrictive radiator guides the light to the specially designed printing laser head via the second polarization-maintaining fiber. With the assistance of the high-precision two-dimensional linear displacement platform and the control of an external computer, the specially designed printing laser head can perform polarization-encoded printing on a specially designed encrypted carrier on the sample stage. The encrypted carrier is a double-sided orthogonally polarized composite polarization film. Specifically, two layers of PVA film with adsorbed iodine molecules are placed on both sides of a polyvinyl alcohol resin film substrate and stretched in an oriented manner. The iodine molecules of the two PVA films are arranged perpendicular to each other, so that the two sides of the transparent film have different dichroisms. In this way, lasers with different polarization directions can selectively cut and process the upper or lower surface.

2. The polarizing film printer as described in claim 1, characterized in that, The fiber laser is a single-polarization pulse fiber laser.

3. The polarizing film printer as described in claim 1, characterized in that, The specially designed printing laser head includes an optical system consisting of a beam shaper and an electrically controlled displacement lens group.

4. The polarizing film printer as described in claim 1, characterized in that, The specially designed printing laser head includes a beam shaper and an electrically controlled displacement lens group connected in sequence. The light enters the beam shaper, which shapes the Gaussian beam output from the second polarization-maintaining fiber into a flat-top beam. The shaped light then passes through the electrically controlled displacement lens group controlled by an electrically controlled linear displacement stage. By changing the relative positions of the lenses in the lens group, the magnification of the lens group can be controlled to output a square light spot of appropriate size on the light output plane, so as to meet the requirements of the target pixel size.

5. The polarizing film printer as described in claim 1, characterized in that, The tail end of the second polarization-maintaining fiber connecting the specially designed printing laser head is provided with a gold-plated square window on the fiber cross-section, which is used to shape the circular light spot into a pixelated square light spot.

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