This PDF file contains the front matter associated with SPIE Proceedings Volume 8776, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

We report holographic recording in thick phenanthrenequinone-doped poly(methyl methacrylate) (PQ/PMMA) photopolymer material via the two-wavelength technique. By using gating light at 325 nm and writing light at 647 nm two-wavelength holographic recording is achieved. Non-volatile readout of a holographic image under 24 hours continuous reconstruction is demonstrated. A four-level modeling for the photochemical procedures of the two-wavelength holographic recording is proposed, and dynamic behaviors of the holograms are illustrated. A planar integrated optical correlator system is constructed by selective writing of holographic optical elements via two-wavelength holographic recording on a photopolymer disk.

Bayfol^® HX film is a new class of recording materials for volume holography. It was commercialized in 2010 and is offering the advantages for full-color recording and moisture resistance without any chemical or thermal processing, combined with low shrinkage and detuning. These photopolymers are based on the two-chemistry concept in which the writing chemistry is dissolved in a preformed polymeric network. This network provides the necessary mechanical stability to the material prior to recording. In addition to the well-known security and imaging applications, Bayfol^® HX film also offers a new opportunity for the manufacturing of volume Holographic Optical Elements (vHOEs) in new optical and optoelectronic applications. For the implementation of holographic recording layouts and associated exposure schedules for these HOEs detailed understanding of the photopolymer material properties and the knowledge how to achieve the optical requirements of dedicated holographic applications are necessary. In this paper we extend the application of our simulation method for the writing mechanism for the Bayfol^® HX photopolymer film. Different photopolymer product variations, including development of photopolymer grades with improved bleaching properties and increased dynamical range, which enable simultaneous multi-color recording, while maintaining a high diffraction efficiency of the recorded holograms are covered. The model is investigated experimentally by recording and evaluation of specifically designed directional diffuser vHOEs as they would be used e.g. for light shaping or light management purposes. One important observation is the capability of Bayfol^® HX film type photopolymers to form highly efficient diffraction gratings even at very high intensity ratios of the reference beam versus the object beam.

When recording hologram in ionic CaF₂ crystal with color centers, the center conversion is accompanied with their spatial redistribution. The peculiar diffusion-drift mechanism of the recording is responsible for the extremely high hologram stability to both heating and illumination of the sample with a hologram by non-coherent radiation. However such photo-thermal treatment of the sample results in partial or total transformation of the center type and modification in their space distribution. Thus, keeping the hologram, such treatment influences its character of diffraction response, diffraction efficiency and profile. This work describes the mechanism and the character of these changes. It is shown that photo-thermal treatment can be used for fabrication of thick (up to 10 mm thickness) high stable holograms when reading out both in visible and infrared ranges of the spectrum.

We report an improvement of the response time and near infrared sensitivity of sillenite crystals Bi₁₂SiO₂₀ (BSO), Bi₁₂TiO₂₀ (BTO) doped with transition metal ions as Ru and Rh. Real-time holographic recording is performed at 1064 nm at a diffusion regime. By using 532 nm light for pre-excitation, significant operation speed of 20 ms is achieved in case of Rh-doped BTO crystal. Further, a possibility to combine doped sillenite plates with liquid crystal into a organic/inorganic hybrid devices (Liquid Crystal Light Valves) is demonstrated, which opens many prospects for further near infrared photonic applications.

Phenanthreneauinone (PQ) doped poly(methyl methacrylate) (PMMA) photopoplymer material has been actively investigated in the literature. Based on the previously developed NPDD model and the analysis of the mechanisms, the behavior of the material is being further studied. The first harmonic refractive index modulation has been examined for both long time post-exposure and under thermal treatment. Twelve and four spatial concentration harmonics in the Fourier series expansions are applied respectively for comparison. Several effects, i.e., the non-local effect, the diffusion of both the ground state and excited states PQ molecules, which occur during and post-exposure in PQ-PMMA photopolymer materials, have been studied under thermal treatment. For long time post-exposure or when the heating treatment is applied, the formation of the photoproduct, PQ/PMMA, has become very important. The effects of nonlocality, diffusion and the different exposing intensities on the distribution of PQ/PMMA over space and higher harmonic PQ/PMMA concentration have been shown. The experimental results are presented, where no thermal treatment is applied.

Holographic Data Storage (HDS) is one of the next generation storage technologies that can actualize high data capacity and high data transfer rate. Since information is recorded 3-dimensionally in a thick medium, data capacity of the HDS is not constrained by diffraction limit. However, behavior of wavefront in an inhomogeneous thick medium is highly complex, and it is hard to handle propagation of wavefront in the medium analytically. Therefore, we establish a numerical technique for analysis of volume holograms. The proposed technique is based on the scalar diffraction theory, which is described as the volume integral equation. By applying Born approximation and angular spectrum method to the volume integral equation, the technique can be applicable for various problems. We analyze characteristics of the volume hologram with spherical reference wave, and confirm effectiveness of the proposed technique. Compared to conventional techniques such as coupled wave analysis, beam propagation method, and finite-difference time domain method, the proposed technique has application potentiality for various problems, and it is easy to implement. In this study, we show effectiveness of the proposed technique by applying to analysis of the volume hologram with spherical reference wave. It can be expected that the proposed technique may become a tool for design of HDS systems.

The mathematical model of signal conversion carried out by holographic optical element (HOE) in holographic stereogram (HS) is presented. Expression for the point spread function (PSF) of HOE in the plane of an observer is obtain as well as the expression for the optimal number of perspectives and plans of HS. Relationship between the observation distance, the size and number of perspectives in HS HOE are considerate. Constraints and future prospects of art and security holography development are disclose. The approach how to optimize HS parameters (such as holopixel size and perspectives number) for current 3D image and HS application is proposed.

A holographic diffraction structure that features stereoscopic pair of records with distorted perspective in the plane of the structure is designed and realized. On normal illumination and oblique binocular observation, the structure provides illusion of seeing an image oriented upright to its plane and located under it. The structure can be used as security DOVID.

Security holograms (SH) are widely used for authenticity protection of document and product due to difficulties of such a protection mark falsification. Mass production of SH uses widespread technology of hot foil or lavsan paper stamping. The quality of holograms significantly depends on perfection of nickel master-matrix that is used in stamping equipment. We represent the method for automated quality inspection of nickel mastermatrix based on digital processing of its surface relief images. Proposed processing algorithm is based on combination of image spatial frequency analysis and image matching using distortion invariant correlation filters. The results of our method application for real master-matrix inspection are shown in this paper.

We propose and demonstrate the recording of hologram of an incoherently illuminated object by using a Sagnac radial shearing interferometer, a Pockels cell and an 8 bit CCD camera. An approach based on statistical optics is used for understanding the concept of recording of an incoherent-object as complex spatial coherence function. The Sagnac radial shearing interferometer is used for the correlation of optical fields and the Pockels cell is used to shift the phase of the interfering fields. The fringe contrast and fringe phase that jointly represent the complex spatial coherence function are measured by applying a 5-step phase shifting algorithm while recording the interferograms. The results of recording and reconstruction of an object illuminated using a light emitting diode, Luxeon Star LXHL-MMID, having spectral width at half maximum of about 35nm at wavelength 530nm, are presented. Due to the implementation of the phase shift by using a Pockels cell, the system is mechanics free and has the potential for automated fast measurement which can be applied for the investigation of dynamic situations. Moreover, the interference of the optical field even with low temporal coherent light is achieved without using any interference filter and a reliable 3-D object reconstruction can be achieved even in an outdoor environment due to the inherent stability provided by the common path interferometer. By changing the shearing parameter, we can tailor the range of the measured coherence function depending on object under test. This could enable one to use it as coherence zooming microscope.

The method of holographic interferometry with the increased sensitivity was applied for measurements of height of nano-steps (from 10 nm and higher) with standard uncertainty about 0.5 nm. The increasing of sensitivity is obtained by interference of waves with mutually complex conjugated phases.

Digital in-line holographic microscopy is a captivating imaging method for industrial applications where large volumes of fluids are to be imaged with microscopic resolution. The lensless holographic in-line imaging setup with a point light source, also known as the Gabor setup, can be built up with just a few, fairly low cost, components. In-line holography is well suited for imaging large volumes with a low concentration of scattering particles as most of the light emitted from the point source should pass through the image volume unscattered. The large depth of field of in-line holographic microscopy makes it possible to image larger volumes with comparable resolutions than what can be achieved with traditional light microscopy methods using low magnification objectives. Despite the many advantages gained over traditional microscopic methods by the use of holographic imaging for large volumes, so far it has only been widely utilized in biological and particle image velocimetry studies. The large depth of field of the holographic microscope permits simultaneous imaging of particles located at different depths without the need for mechanical scanning, and allows the use of large diameter fluidic channels which are not as prone to clogging and enable higher flow rates than smaller fluidic channels. In this paper, we present a digital in-line holographic microscope based measurement principle for measuring the solid particle content of fluids. The method proposed is demonstrated on bio-oil samples whose solid contents are less than 0.01 weight percentage.

A web-service for digital video hologram processing based on Berkeley Open Infrastructure for Network Computing (BOINC) is proposed. Proof-of-concept is confirmed for broad spectrum of applications such as digital holographic particle image velocimetry, water biomonitoring by means zooplankton analysis and digital holographic disdrometry. The snapshots presented in this paper were reconstructed using the proposed web-service.

Holographic techniques are powerful tools to study photosensitive materials due to the high sensitivity of diffraction measurement and the ability to detect dynamic gratings. The self diffraction technique consists in to project an interference fringe pattern into the photosensitive material and to measure, in real time, the self-diffraction of the interfering beams, at the grating generated in the photosensitive material. Besides the higher sensitivity, such measurement allows to measure simultaneously and separately the phase and the amplitude grating contributions, as well as thin or thick gratings. In order to demonstrate potentiality of this technique we measured the kinetic constant of the photo-reaction in positive photoresists (AZ types) and negative SU-8 photoresist, as well as the maximum values of the refractive index and of the absorption coefficient modulations induced in these materials at different wavelengths of exposure. The same measurements were performed in SB based chalcogenide glasses in order to evaluate the potential of such materials to be used as optical data storage devices.

Today, along with the wider use of high-speed information networks and multimedia, it is increasingly necessary to have higher-density and higher-transfer-rate storage devices. Therefore, research and development into holographic memories with three-dimensional storage areas is being carried out to realize next-generation large-capacity memories. The mainstream in the world is the angle multiplexing method, however, it costs too much and its control is quite severe. In such situation, we study about shift multiplexing method because it costs not much and its control is easier than the angle multiplexing. In this experiment, we examined shift selectivity of track direction, radial direction and vertical direction of the medium. As a result, combining these different kinds of selectivity, we found a possible multiplexing way to achieve several tera bits per inch square density recording.

We propose the use of radical-mediated thiol-yne step-growth photopolymerizations for volume holographic recording in NPC films to overcome the drawback of low crosslinking densities but retain the advantage of low shrinkage in the thiol-ene photopolymerizations. The thiol-yne photopolymerization mechanism is different from the thiol-ene photopolymeriztions in the sense that each alkyne functional group can react consecutively with two thiol functional groups. We show that thiol-yne based NPC films dispersed with silica nanoparticles give the saturated refractive index change as large as 0.008 and the material recording sensitivity as high as 2005 cm/J at a wavelength of 532 nm, larger than the minimum acceptable values of 0.005 and 500 cm/J, respectively, for holographic data storage. We also show that the shrinkage of a recorded hologram can be as low as that of thiol-ene based NPC films and that the thermal stability is improved better. In addition, we demonstrate digital data page recording in thiol-yne based NPC films, showing a low symbol error rate and a high signal-to-noise ratio to be 2.8×10⁻⁴ and 8, respectively.

In recent work carried out, we introduced the developments made to the Non-local Photo-polymerization Driven Diffusion model, and illustrate some of the useful trends, which the model predicts and then analyse their implications on photopolymer improvement. The model was improved in its physicality through the inclusion of viscosity effects (changes in fractional free volume), multiple components and their photo-kinetic and photo-physical behaviour, and free space vacuoles. In this paper, we further explore this model to provide a more rigorous and informed basis for predicting the behaviours of photopolymer materials in both photo-chemical and photo-physical sides. Such improvements include a) the analysis of the effects of viscosity on the refractive index modulation, b) the effects of the introduction of free space holes, e.g. the volumetric changes, and c) an examination of the effects of local temperatures and various concentration ratios to optimise material performance.

In this work we are going to apply GPU (Graphical Processing Units) with CUDA environment for scientific calculations, concretely high cost computations on the field of digital holography. For this, we have studied three typical problems in digital holography such as Fourier transforms, Fresnel reconstruction of the hologram and the calculation of vectorial diffraction integral. In all cases the runtime at different image size and the corresponding accuracy were compared to the obtained by traditional calculation systems. The programs have been carried out on a computer with a graphic card of last generation, Nvidia GTX 680, which is optimized for integer calculations. As a result a large reduction of runtime has been obtained which allows a significant improvement. Concretely, 15 fold shorter times for Fresnel approximation calculations and 600 times for the vectorial diffraction integral. These initial results, open the possibility for applying such kind of calculations in real time digital holography.

In this work, we designed and recorded two-dimensional Hexagonal Photonic Crystals (2D-HPC) layers, with a linear waveguide, in erbium doped GeO₂-Bi₂O₃-PbO-TiO₂ glassy films, by combining the techniques of holographic recording and femtosecond (fs) laser micromachining. The 2D-HPC is recorded holographically in a photoresist film coated on a glass substrate by exposing the sample to the same interference pattern twice and rotating the sample of 60° between the exposures. After the development a two dimensional hexagonal array of photoresist columns remain on the glass substrate. The recording of the waveguide is made by a fs laser micromachining system focused at sample surface. The laser spot produces the ablation of the photoresist columns generating a defect line in the periodic hexagonal array. After the recording of the photoresist template, the erbium doped GeO₂-Bi₂O₃-PbO-TiO₂ film is evaporated on the photoresist and finally the photoresist template is removed using acetone. The design of the geometrical parameters of the 2D-HPC is performed by calculation of the dispersion mode curves of the photonic crystal using a 2D finite element method. The proper geometrical parameters depend on both the refractive index of the glass film and thickness. Such parameters as well as the period of the 2D-HPC have been defined in order to obtain a photonic band gap in the region of erbium luminescence band. In such condition the erbium luminescence will propagate only through the waveguide.

The photopolymer materials in Holographic Data Storage (HDS) have been increasingly studied due to their growing interest in applications. In this article we make use of the time varying parameters to study the behaviors of the photopolymer materials during exposure time. The nonlocal photo-polymerization driven diffusion (NPDD) model and electromagnetic theories of Maxell equations are combined in our model development. Moreover in this model, the theories of the material molecule polarization and the excited photosensitizer conductivity production are also introduced. The numerical simulation results in both cases of transmittance and diffraction efficiency are all analyzed. Several physical parameters and photochemical rate constant values are estimated by fitting the model predictions to the experimental results of AA/PVA material.

We present our first experimental results of lens irradiation obtained with ultrashort pulse lasers. The irradiation was done with the Ti:Safire laser which irradiates at 800 nm with a repetition rate of 76 MHz. The maximum average intensity used was 300mW, with pulses of 4 nJ. The holographic images obtained have given us information about the focusing process of the lens capsule as well as its rupture, thus indicating the level of penetration in the lens and capsule rupture. The results obtained in these first experiments allow us to establish protocols and techniques to break the capsule of the lenses as well as to carry out possible modifications inside the lens. As the optical system developed works in real time, it is possible to perform dosimetry measurements in the light-lens interaction processes giving quantitative information about the breakdown of the tissue structures. In future projects the possible side effects of thermal action and local modification of the capsule will be analyzed; these are important aspects in the field of noninvasive lens surgery.

The holographic optical elements (HOE) for holographic indicators and methods of their production on the photosensitive materials are described. A distinctive feature of this optical scheme is the zone record of diffraction gratings and HOE, i.e., grating is divided into separate fragments that stitching at the recording process with a high-precision motion system of the plate.

The given work investigates principles of recording, calculation, and security aspects of ‘hidden image’ effect in digital holograms that are intended for security applications. Dot-matrix and image-matrix technologies of optical recording can be widely used for recording protective holograms with such type of security features. When a collimated laser beam falls on and then is reflected from the section of holograms, containing a protective ‘hidden image’ element, a graphic image can be seen in the projection of diffracted light on the frosted screen. The present work also discusses a method of personalizing the ‘hidden image’ effect with the help of laser demetallization. In this way the hidden image can be individualized for each hologram sticker and contain additional information such as a number, text or logotype. The attractiveness of this method is in the possibility of achieving a considerable increase of the protective characteristic of holograms and incorporating additional variable information in them, as well as in providing both visual and automatic ways of checking authenticity of a hologram.

Classic holographic memory systems use two-beam approach based on fixation of interference pattern between object and reference coherent beams on holographic recording medium. The size of single pattern is about several micrometers. High precision optical set up is required to form such a microhologram, that is the reason of excessive price for holographic recording devices. Methods of computer holographic synthesis allow to calculate holographic patterns numerically as 2D images. These images can be realized with the use of spatial light modulator, then reduced in optical projection system and exposed on holographic medium. In this paper we represent the research of holographic memory system based on computer generated Fourier holograms projection.