The improvement of fill factor of holographic micromirror array (HMA) with holographic waveguide-type for threedimensional (3D) augmented-reality (AR) display system. Our proposed 3D AR system was created and briefly explain it; there have two the HOE optical film at in-and out coupler of the waveguide. In-coupler HOE is our fabricated HMA, it has a same role with optical microlens-array. HMA is integrate the displaying elemental image set (EIS) from micro display which EIS was generated by the integral imaging technology. The micro display has a 6 mm by 8mm size, 48single elemental images and micro display was located g distance from holographic waveguide which waveguide thickness was 5mm. EIS was displayed by micro display to holographic waveguide. HMA was stick with holographic waveguide and located in opposite side of waveguide and micro display. Micro display was display forward to holographic waveguide and fabricated HMA, then displayed EIS is reflected and integrated at the in-coupler HMA and integrated 3D image was through the holographic waveguide by HMA recorded angle. 3D images of internal reflect in the holographic waveguide was 1 time. 3D image was also reflected at the out-coupler HOE which role was same as optical mirror and reflect to observer’s eye. At least observer as the reconstructed images and real object out and reflects by out-coupler HOE.
In this paper, A full-color Denisyuk-type hologram using photopolymer has been recorded by the sequential exposure method. The photopolymer's optical characteristics show that inhibition periods of the photopolymer at three lasers are different in the same beam intensity. To increase the average diffraction efficiency of a full-color holographic optical element (HOE), the three lasers should be sequentially exposed to the photopolymer. The experimental results show that the average efficiency of a full-color reflection HOE is 59.6% and the standard deviation is 2.1. Also, the full-color hologram recorded in a one-layer photopolymer can reconstruct a high-quality image.
The improvement of holographic waveguide-type two-dimensional/three-dimensional (2D/3D) convertible augmentedreality (AR) display system using the liquid-crystalline polymer microlens array (LCP-MA) with electro-switching polarizer is proposed. The LCP-MA has the properties such as a small focal ratio, high fill factor, low driving voltage, and fast switching speed, which utilizes a well-aligned reactive mesogen on the imprinted reverse shape of the lens and a polarization switching layer. In the case of the holographic waveguide, two holographic optical elements (HOE) films are located at the input and output parts of the waveguide. These two HOEs have functions like mirror and magnifiers. Therefore, it reflects the transmitted light beams through the waveguide to the observer's eye as the reconstructed images. The proposed system has some common features like holographic AR display’s lightweight, thin size, and the observer can see the 2D/3D convertible images according to the direction of the electro-switching polarizer, with the real-world scenes at the same time. In the experiment, the AR system has been successfully verified that the real-world scene and reconstructed 2D/3D images were observed simultaneously.
We proposed a full-color three-dimensional holographic waveguide-type augmented-reality display system based on integral imaging using the holographic optical element-mirror array. As same as the conventional holographic waveguide, two holographic optical elements are utilized as in- and out-couplers that are located at the input and output parts of the waveguide. The main roles of these films are that reflecting the light beams come from the microdisplay into the waveguide, transmitting the reconstructed by the HOE-MA, three-dimensional image while a reflecting to the observer’s eye. In the experiment, the augmented-reality feature has been successfully verified that the real-world scene and reconstructed virtual three-dimensional image were observed simultaneously.
We proposed a three-dimensional (3D) holographic waveguide-type augmented reality (AR) system based on integral imaging using the mirror array. As same with the conventional holographic waveguide, two holographic optical element (HOE) films are utilized as in- and out-couplers, that are located at the input and output parts of the waveguide. The main role of the in-coupler HOE is that reflecting the light beams come from the micro display into the waveguide, and out-coupler reflects the transmitted light beams through the waveguide to the observer eye. On the basic of the main advantages of conventional holographic waveguide structure such as the light-weight and thin-size, the proposed system has an additional critical advantage that the observer can see the realistic 3D visualizations reconstructed by the outcoupler HOE-mirror array (HOE-MA), instead of simple two-dimensional images, with the real-world scenes at same time. In the experiment, the AR feature has been successfully verified that the real-world scene and reconstructed virtual 3D image were observed simultaneously.
A design and implementation of full-parallax holographic stereogram printer is presented. The holographic stereogram is synthesized using 2D perspective images of the 3D object that are rendered from multiple directions. The perspective images of the 3D scene are firstly captured by a virtual camera and transformed to two-dimensional holographic elements called hogels. The hogels are exposed using the perspective images to form the whole holographic stereogram. After all the hogels are exposed successively, a holographic stereogram can be achieved. Numerical simulation and optical reconstructions are implemented.
Holographic gratings with asymmetric structure are widely used to couple light into and out of waveguides due to
their high diffraction efficiencies and planar packaging. In this paper, a holographic grating coupler based on the
photopolymer has been designed and experimentally demonstrated at wavelength of 405nm. To achieve the high
diffraction efficiencies in the structure, we investigated the optical properties of the coupler according to the
exposure energy at the 405nm wavelength. In the holographic recording for the asymmetrical geometry, we
researched the optical characteristics of the Dupont photopolymer HRF150-38 as the correction of the Bragg angles
shift because of shrinkage factor and the diffraction efficiency. The performance and the optical characteristics of
the coupler using volume holographic grating will discussed in detail.
KEYWORDS: Holography, Diffraction, 3D image reconstruction, Holograms, Digital imaging, Sol-gels, Data storage, Digital holography, Holographic materials, Optical properties
Monomer diffusion in an organic-inorganic nanocomposite films during the holographic recording was investigated. The photopolymer films with low shrinkage were prepared by dispersing an aromatic methacrylic monomer and a photo-initiator in organic-inorganic hybrid sol-gel matrices. The shrinkage of the photopolymer film and the diffusion of monomers during the holographic recording could be controlled by optimizing the content of an organically modified silica precursor (ORMOSIL) in the sol-gel matrices. The photopolymer film showed high diffraction efficiency (>90%) under an optimized condition. Photo-sensitivity, angular selectivity and application potential for holographic data storage and optical application will be discussed.
Tir- and mono functional monomers were dispersed in a solution of polysulfone in organic solvent containing a photo initiator and other additives. New photopolymer film was prepared by dispersing acrylic monomer in a polysulfone matrix. The Polysulfone was adopted as a binder since it affords transparent thick films with low dimensional changes during holographic recording. Optical property of the photopolymer showed high diffraction efficiency (>90%) under an optimized optical condition at 532nm laser. The angular selectivity for angular multiplexing page oriented holographic memories (POHMs), the maximum diffraction efficiency of the material during holographic recording, the diffraction efficiency of the films as a function of an incident angle of two beams, exposure energy for saturation of the holographic material and application for holographic data storage will be discussed.
The effect of monomer functionality on the diffraction efficiency of the photopolymer containing multi- and monofunctional monomers was investigated. A mixture of tri-, di-, and mono functional monomers were dispersed in a solution of polysulfone dissolved in organic solvent containing a photo initiator. The monomer contents were varied by changing the ratio between them. The average functionality (Fav = Σ φiFi) was determined, where φi is the mol fraction of the monomer with functionality Fi. The holographic recording was performed and diffraction efficiency (η) of each film was determined by using a 532 nm laser. In the photopolymer film having an optimized composition, η was increased within 20 sec and reached a maximum of >90% with an exposure power of 5 mW laser. The rise of η (response time), maximum η, and stability of η value over prolonged recording were dependent on the monomer structure and composition and the average functionality. The result could be ascribed to the reactivity and functionality of monomers under interference light, to generate refractive index contrast.
Holographic transmission gratings with 0o;-Bragg angle are widely used to couple light into and out of waveguides due to their high diffraction efficiencies and planar packaging. In this paper, a holographic grating coupler based on the photopolymer has been designed and experimentally demonstrated. To achieve the high diffraction efficiencies, we investigate the optical properties of the coupler according to the exposure energy at the 405 nm wavelength. For the asymmetrical geometry with 72othe correction of the Bragg angles shift of about 0.95o; and 3.45o;, which are induced by the 7.86% shrinkage factor, is successfully demonstrated. The performance and the optical characteristics of the coupler using volume holographic grating are discussed in detail.
Organic-inorganic nanocomposite films were prepared by dispersing an aromatic methacrylic monomer and a photo-initiator in organic-inorganic hybrid sol-gel matrices. The film properties could be controlled by optimizing the content of an organically modified silica precursor (TSPEG) in the sol-gel matrices. The photopolymer film modified with the organic chain (TSPEG) showed high diffraction efficiency (>90%) under an optimized condition. High diffraction efficiency could be ascribed to the fast diffusion and efficient polymerization of monomers under interference light to generate refractive index modulation. The TSPEG modified photopolymer film could be successfully used for holographic memory. Angular selectivity of the film were 0.46 ~ 0.16 depending on the film thickness in the incident angles between 20° ~ 70°. A digital holographic image and a real object were recorded successfully in the photopolymer film.
A new structure of polarization-selective elements consisting of two holographic gratings and a dove prism coupler is proposed. The absence of a multi-stage wave-guide, compact size, and lightweight volume are the outstanding features of the new structure. Based on the coupled-wave theory, the analysis and design of the structure are discussed in detail to calculate the required index modulation. Several parameters such as the recording intensity, the exposure time, and the recording angles for the fabrication of the proposed element are determined. Under the conditions the element is fabricated in Dupont photopolymer HRF-150-38 material and with the operating wavelength of 532nm. A simplified pick-up head is constructed to evaluate the performance of the fabricated element.
Optical transparency and high diffraction efficiency are two essential factors for high performance of the photopolymer. Optical transparency mainly depends on the miscibility between polymer binder and photopolymerized polymer, while diffraction efficiency depends on the refractive index modulation between polymer binder and photopolymerized polymer. For most of organic materials, the large refractive index difference between two polymers accompanies large structural difference that leads to the poor miscibility and thus poor optical quality via light scattering. Therefore, it is difficult to design a high-performance photopolymer satisfying both requirements. In this work, we prepared a new phase-stable photopolymer with large refractive index modulation and investigated the optical properties. Our photopolymer is based on modified poly (methyl methacrylate) as a polymer binder, acryl amide as a photopolymerizable monomer, triethanolamine as initiator, and yellow eosin as a photosensitizer at 532nm. Diffraction efficiency over 85% and optical transmittance over 90% were obtained for the photopolymer.
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