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In this paper, we propose a new approach for fabrication processes of microstructures composed of diffractive optical elements (DOE) and security elements. The holographic lithography is combined with laser lithography to obtain highly secured holographic labels for products protection. The secret key is an untraceable and hardly reproducible geometry and can be embedded in the labels or stickers to increase the level of security and diminish the possibility of products counterfeiting. In our process, the holographic structure composed of DOEs, and the key are designed separately by two authorized designers and recombined using double exposure followed by a single development step. The layout of microstructures that composes the security key are known only by the designer.

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Polymer optics are widely used in various applications, replacing traditional glass lenses. The ability to create free-form and micro-structured optics, as well as fast replication, gives them major advantages over traditional glass lenses. However, the fabrication of complex optical components requires full process control and understanding of influencing factors on the quality of the polymer optical parts. In this work, a curved diffractive optical element (DOE) is fabricated using injection compression molding. Different gate designs were evaluated and the movement of the compression stamper was optimized to obtain good filling behavior. The process stability was analyzed and improved by controlling the melt temperature precisely. Finally, the molding parameters were optimized, focusing on the mold temperature, melt temperature and compression force. Curved diffractive optical elements were replicated with feature sizes of 1.6 �m. The experiments showed that all aspects of the molding process have to be controlled perfectly to produce complex polymer optics. High mold temperatures and compression force are necessary to replicate micro-structured features. The work presents a broad investigation and description of the fabrication process and their influences.
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In this paper, we present the design, fabrication and optical characterization of computer-generated holograms (CGH) encoding information for light beams carrying orbital angular momentum (OAM). Through the use of a numerical code, based on an iterative Fourier transform algorithm, a phase-only diffractive optical element (PH-DOE) specifically designed for OAM illumination has been computed, fabricated and tested. In order to shape the incident beam into a helicoidal phase profile and generate light carrying phase singularities, a method based on transmission through high-order spiral phase plates (SPPs) has been used. The phase pattern of the designed holographic DOEs has been fabricated using high-resolution Electron-Beam Lithography (EBL) over glass substrates coated with a positive photoresist layer (polymethylmethacrylate). To the best of our knowledge, the present study is the first attempt, in a comprehensive work, to design, fabricate and characterize computer-generated holograms encoding information for structured light carrying OAM and phase singularities. These optical devices appear promising as high-security optical elements for anti-counterfeiting applications.
Conference Paper
A novel concept for an optical holographic anti-counterfeit tag is presented and demonstrated experimentally. Under laser illumination, the tag projects a 2D barcode image which carries a unique speckle pattern serving as its “fingerprint”.
Authentication of encoded information is a popular current trend in optical security. Recent research has proposed the production of secure unclonable ID tags and devices with the use of nanoscale encoding and thin-film deposition fabrication techniques, which are nearly impossible to counterfeit but can be verified using optics and photonics instruments. Present procedures in optical encryption provide secure access to the information, and these techniques are improving daily. Nevertheless, a rightful recipient with access to the decryption key may not be able to validate the authenticity of the message. In other words, there is no simple way to check whether the information has been counterfeited. Metallic nanoparticles may be used in the fabrication process because they provide distinctive polarimetric signatures that can be used for validation. The data is encoded in the optical domain, which can be verified using physical properties with speckle analysis or ellipsometry. Signals obtained from fake and genuine samples are complex and can be difficult to distinguish. For this reason, machine-learning classification algorithms are required in order to determine the authenticity of the encoded data and verify the security of unclonable nanoparticle encoded or thin-film-based ID tags. In this paper, we review recent research on optical validation of messages, ID tags, and codes using nanostructures, thin films, and 3D optical codes. We analyze several case scenarios where optically encoded devices have to be authenticated. Validation requires the combined use of a variety of multi-disciplinary approaches in optical and statistical techniques, and for this reason, the first five sections of this paper are organized as a tutorial.
In this paper we present a software for the design and visualization of holographic elements containing full scale of visual effects. It enables to simulate an observation of the holographic elements under general conditions including different light sources with various spectral and coherence properties and various geometries of reconstruction. Furthermore, recent technologies offer interesting possibilities for the 3D visualization such as the 3D techniques based on shutter or polarization glasses, anaglyphs, etc. The presented software is compatible with the mentioned techniques and enables an application of the 3D hardware tools for visualization. The software package can be used not only for visualization of the existing designs, but also for a fine tuning of the spatial, kinetic, and color properties of the hologram. Moreover, the holograms containing all types of the 3D effects, general color mixing, kinetic behavior, diffractive cryptograms, etc. can be translated using the software directly to a high resolution micro-structure.
With the increase of globalization in trading and online shopping, phony products are on the rise in the market. This article introduces a range of technologies that have been implemented in the supply chain to deter counterfeiters. Technology for both product authentication and tracing and tracking products in the supply chain will be discussed, along with the advantages and disadvantages of each solution. Additionally, success stories on combating counterfeits are introduced. Finally, issues related to rising anti-counterfeiting costs, collaborative efforts in fighting fakes, and a multi-pronged plan are explored.
The experimental investigation of a novel technical approach for formation of security diffraction structures with high degree of protection based on a combined optical and electron-beam lithography techniques are presented.
Replication technologies such as embossing, moulding and casting are highly attractive for the fabrication of surface relief Diffractive Optical Element (DOE) microstructures. They have very high resolution, typically in the nanometer range, and allow the fabrication of large area, complex microstructures by low-cost, high volume industrial production processes. Their use is already well established for gratings, holograms and diffractive foil, and the extension to the fabrication of deeper and higher aspect ratio microstructure is underway. The combination of replication technology with other processes such as dry etching and thin film coating can also offer new possibilities in the design of DOEs suitable for mass-production. Replication is expected to become a key technology for the microfabrication of DOEs in the future. This paper reviews the major DOE replication techniques and describes recent work and results.
Electroforming - A Unique Metal Fabrication Process
  • R Parkinson
R. Parkinson, Electroforming -A Unique Metal Fabrication Process, NiDI Technical Series No 10084 (1998), pp.1-12
Mass Replication of holograms and Diffraction Gratings by Embossing, IS&T's 50th Annual Conf
  • C Newswanger
C. Newswanger, Mass Replication of holograms and Diffraction Gratings by Embossing, IS&T's 50th Annual Conf., 1997
Synthetic Image Holograms, in Advanced Holography -Metrology and Imaging Edited by I. Naydenova
  • J Oda
  • M Škeren
  • Pavel Fiala
J. Oda, M. Škeren, Pavel Fiala, Synthetic Image Holograms, in Advanced Holography -Metrology and Imaging Edited by I. Naydenova, InTech 2011, pp 209-232