In order to improve the effect, clarity and resolution of anti-counterfeiting, this paper proposes a method of reflection volume holographic three-dimensional (3D) anti-counterfeiting. This method adopts reflection volume holographic interference recording of 3D object to achieve 3D anti-counterfeiting. The principle of reflection volume holography was analyzed by using Kogelnik’s coupled wave theory. A reflection volume holographic anti-counterfeiting recording optical path based on a monochromatic laser was constructed. Photopolymer is used as the volume holographic recording material, and a metal school badge is used as the object. Experimental results show that the reflection holographic gratings can record and reproduce 3D object, and the 3D shape of the reproduced image is consistent with the object, which improves the effect of anti-counterfeiting.
Volume holograms can record and reproduce three-dimensional object. Compared with planar holograms, volume holograms can improve the resolution, stereo perception and realism of anti-counterfeiting, and realize three-dimensional anti-counterfeiting. In order to improve the diffraction efficiency and anti-counterfeiting effect of volume holographic anti-counterfeiting, this paper proposes a reflection volume holographic three-dimensional anti-counterfeiting method based on photopolymer. The diffraction characteristics and influencing factors are analyzed by Kogelnik’s coupled wave theory. Based on Piazzolla’s monomer diffusion model, the effects of exposure energy and exposure intensity on refractive index modulation and diffraction efficiency were studied. The simulation results show that the reflection volume holograms can achieve a greater refractive index modulation, with higher diffraction efficiency, stronger wavelength selectivity, which enhances the effect of three-dimensional anti-counterfeiting.
Volume holograms can achieve concentration of sunlight, but it has shortcomings such as small concentration angle, dispersion, and complex production process of the volume holography material, which is difficult to mass produce. This paper proposes a method based on the metasurface concentrating sunlight. We analyzed the mechanism of volume holographic light focusing by Kogelnik coupling wave theory, which is greatly limited by wavelength selectivity. Utilizing the metasurface control mechanism on the wave front phase, the array arrangement that meets the light concentrating effect was designed. Simulation analysis shows that the metasurface can achieve light concentration in the visible light band with low dispersion.
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