New combined embossed hologram originating technique was developed by the international team of holography experts. The technique merges deep 3D holographic images with commonly used hologram security features. Deep 3D images were first recorded on photoresist with Geola's holographic printer containing their proprietary pulsed laser. Optical security features were then overexposed onto the photoresist plates containing latent images of deep 3D scenes. The photoresist plates with several exposures (containing optical security features and deep 3D images) were developed. Embossed holograms, containing such effective public security features as full colour 3D images, guilloches, rainbow patterns were manufactured. Manufactured embossed holograms also contained such optical security features as microtext and laser readable hidden image.

We propose the coherent backlight unit (BLU) using Holographic Optical Element (HOE) for full-color flat-panel holographic display. The HOE BLU consists of two reflective type HOEs that change the optical beam path and shape by diffraction. The diverging incident beam is transformed to the collimated beam which has a very small diffraction angle (7.5°) by HOE 1 (H1) in order to illuminate the whole display. This collimated beam is converged to a point at a distance from the glass substrate by HOE 2 (H2). As a result, the diverging incident beam is converted to a point light by H1 and H2. When the high resolution Spatial Light Modulator (SLM) displaying Computer Generated Hologram (CGH) is illuminated by HOE BLU, the hologram image is displayed at a view point near focal point. Practically, we fabricated the full color HOE BLU for 5.5" flat panel holographic display by using the proposed design. At least 5.5" size of HOE is required to illuminate the whole panel. For this reason, we recorded 150 mm x 90 mm size HOE on the 10 mm thickness glass substrate. This HOE BLU exhibits a total efficiency of 8.0% at Red (660 nm), 7.7% at Green (532 nm), 3.2% at Blue (460 nm) using optimized recording conditions for each wavelength. Finally, a bright full color hologram image was achieved.

The investigation of integrated circuits (ICs), such as microcontrollers (MCUs) and system on a chip (SoCs) devices is a topic with growing interests. The need for fast and non-destructive imaging methods is given by the increasing importance of hardware Trojans, reverse engineering and further security related analysis of integrated cryptographic devices. In the field of side-channel attacks, for instance, the precise spot for laser fault attacks is important and could be determined by using modern high resolution microscopy methods. Digital holographic microscopy (DHM) is a promising technique to achieve high resolution phase images of surface structures. These phase images provide information about the change of the refractive index in the media and the topography. For enabling a high phase stability, we use the common-path geometry to create the interference pattern. The interference pattern, or hologram, is captured with a water cooled sCMOS camera. This provides a fast readout while maintaining a low level of noise. A challenge for these types of holograms is the interference of the reflected waves from the different interfaces inside the media. To distinguish between the phase signals from the buried layer and the surface reflection we use specific numeric filters. For demonstrating the performance of our setup we show results with devices under test (DUT), using a 1064 nm laser diode as light source. The DUTs are modern microcontrollers thinned to different levels of thickness of the Si-substrate. The effect of the numeric filter compared to unfiltered images is analyzed.

In this paper, we report three-dimensional(3D) measurement results of structural parameters of fusion spliced optical fibers using digital holographic microtomography. A holographic setup in microscopy configuration with the sample-fixed and setup-rotating scheme is established. A series of holograms is recorded from various incident angles. Then the filtered backprojection algorithm is applied to reconstruct the 3D refractive index (RI) distributions of the fusion spliced optical fibers inserted in the index-matching liquid. Experimental results exhibit the internal and external shapes of three kinds of fusion splices between different fibers, including a single-mode fiber(SMF) and a multimode fiber, an SMF and a panda polarization maintaining fiber (Panda PMF), and an SMF and a bow-tie polarization maintaining fiber (Bow-Tie PMF). With 3D maps of RI, it is intuitive to observe internal structural details of fused fibers and evaluate the splicing quality. This paper describes a powerful method for non-invasive microscopic measurement of fiber splicing. Furthermore, it provides the possibility of detecting fiber splicing loss by 3D structures.

This investigation explores representing information through data visualization using the medium holography. It is an exploration from the perspective of a creative practitioner deploying a transdisciplinary approach. The task of visualizing and making use of data and “big data” has been the focus of a large number of research projects during the opening of this century. As the amount of data that can be gathered has increased in a short time our ability to comprehend and get meaning out of the numbers has been brought into attention. This project is looking at the possibility of employing threedimensional imaging using holography to visualize data and additional information. To explore the viability of the concept, this project has set out to transform the visualization of calculated energy and fluid flow data to a holographic medium. A Computational Fluid Dynamics (CFD) model of flow around a vehicle, and a model of Solar irradiation on a building were chosen to investigate the process. As no pre-existing software is available to directly transform the data into a compatible format the team worked collaboratively and transdisciplinary in order to achieve an accurate conversion from the format of the calculation and visualization tools to a configuration suitable for synthetic holography production. The project also investigates ideas for layout and design suitable for holographic visualization of energy data. Two completed holograms will be presented. Future possibilities for developing the concept of Holographic Data Visualization are briefly deliberated upon.

The art of the last fifty years has significantly surrounded the presence of the body, the relationship between human and interactive technologies. Today in interactive art, there are not only representations that speak of the body but actions and behaviours that involve the body. In holography, the image appears and disappears from the observer’s vision field; because the holographic image is light, we can see multidimensional spaces, shapes and colours existing on the same time, presence and absence of the image on the holographic plate. And the image can be flowing in front of the plate that sometimes people try touching it with his hands. That means, to the viewer will be interactive events, with no beginning or end that can be perceived in any direction, forward or backward, depending on the relative position and the time the viewer spends in front of the hologram. To explore that feature we are proposing an installation with four holograms, and several sources of different kind of sounds connected with each hologram. When viewers will move in front of each hologram they will activate different sources of sound. The search is not only about the images in the holograms, but also the looking for different types of sounds that this demand will require. The digital holograms were produced using the HoloCam Portable Light System with the 35 mm camera Canon 700D to capture image information, it was then edited on computer using the Motion 5 and Final Cut Pro X programs.

In terms of contemporary art, time-based media generally refers to artworks that have duration as a dimension and unfold to the viewer over time, that could be a video, slide, film, computer-based technologies or audio. As part of this category, holography pushes this visual-oriented narrative a step further, which brings a real 3D image to invite and allow audiences revisiting the scene of the past, at the moment of recording in space and time. Audiences could also experience the kinetic holographic aesthetics through constantly moving the viewing point or illumination source, which creates dynamic visual effects. In other words, when the audience and hologram remain still, the holographic image can only be perceived statically. This unique form of expression is not created by virtual simulation; the principal of wavefront reconstruction process made holographic art exceptional from other time-based media. This project integrates 3D printing technology to explore the nature of material aesthetics, transiting between material world and holographic space. In addition, this series of creation also reveals the unique temporal quality of a hologram’s presence and absence, an ambiguous relationship existing in this media.

During 2015, the International Year of Light, a traveling exhibition was developed and dedicated to holography. Despite the holograms are present in our day life, through several formats and different applications, for general public these 3D images are strange elements from complex technology. This exhibition explores several contents related with holograms, such as history, techniques, equipments, setups and applications and it involves a main structure with six interactive exhibits and a lab for hologram recording. The exhibition includes a group of nine art holograms, a workshop table dedicated to scratch holograms and a touch screen with information about holography, which can be download on-site or at home. All these contents, based on hands-on activities, are organized into five areas: "see", "do", "explore", "holo kids" and "to know more". The holography lab is based on a portable Denisyuk system and it allows the public to notice the typical darkroom environment needed to work on holography and also it allows visitors to make holograms as a souvenir of the exhibition. There are two types of visits: "Exploring the world of holograms" focus on visiting all contents and "Let's make an hologram" that, besides visiting, allows also to make holograms. Light Windows is an exhibition dedicated to the general public that during the last year has been traveling around six Portuguese cities. This paper will present and analyze all results obtained and it will discuss exhibitions impact on visitors.

Volume Holographic Optical Elements (vHOEs) gained wide attention as optical combiners for the use in augmented and virtual reality (AR and VR, respectively) consumer electronics and automotive head-up display applications. The unique characteristics of these diffractive grating structures – being lightweight, thin and flat – make them perfectly suitable for use in integrated optical components like spectacle lenses and car windshields. While being transparent in Off-Bragg condition, they provide full color capability and adjustable diffraction efficiency. The instant developing photopolymer Bayfol® HX film provides an ideal technology platform to optimize the performance of vHOEs in a wide range of applications. Important for any commercialization are simple and robust mass production schemes. In this paper, we present an efficient and easy to control one-beam recording scheme to copy a so-called master vHOE in a step-and-repeat process. In this contact-copy scheme, Bayfol® HX film is laminated to a master stack before being exposed by a scanning laser line. Subsequently, the film is delaminated in a controlled fashion and bleached. We explain working principles of the one-beam copy concept and discuss the mechanical construction of the installed vHOE replication line. Moreover, we treat aspects like master design, effects of vibration and suppression of noise gratings. Furthermore, digital vHOEs are introduced as master holograms. They enable new ways of optical design and paths to large scale vHOEs.

The mechanical loading of dental restorations and hard tissue is often investigated numerically. For validation and optimization of such simulations, comparisons with measured deformations are essential. We combine digital holographic interferometry and digital speckle photography for the determination of microscopic deformations with a photogrammetric method that is based on digital image correlation of a projected laser speckle pattern. This multimodal workstation allows the simultaneous acquisition of the specimen’s macroscopic 3D shape and thus a quantitative comparison of measured deformations with simulation data. In order to demonstrate the feasibility of our system, two applications are presented: the quantitative determination of (1) the deformation of a mandible model due to mechanical loading of an inserted dental implant and of (2) the deformation of a (dental) bridge model under mechanical loading. The results were compared with data from finite element analyses of the investigated applications. The experimental results showed close agreement with those of the simulations.

Since 1997 a program dedicated to holography has been developed and implemented in Portugal. This program started with focus on schools and science education. The HoloNetwork was created and it has been spread at a National level, involving a group of thirty schools and hundreds of students and teachers. In 2009 this network started to work to achieve a new target, the general public. With this goal, a larger program was developed with focus on science and society and on science communication through holography. For the implementation of this new program, special holography outreach activities were built, dedicated to informal learning and seven Science Centers around Portugal were add into the HoloNetwork. During last years, we have been working on holography, based on two main branches, one dedicated to schools and with the aimed to promote physics teaching and to teach how to make holograms, and another dedicated to society and with the aimed to promote holography and to increase scientific literacy. This paper would analyze the educational program, all holography outreach activities, exhibitions or events, all equipments, materials and setups used and it would present the holographic techniques explored with students or with the public. Finally, the results obtained in this work would be present and explored, with focus on students impact and outcomes, taking into account the public engagement on holography and its effect into scientific culture and analyzing the quality of holograms made by students and by the general public. subject.

We report on the numerical analysis of Bragg polarization gratings (PGs), especially those formed with liquid crystals, and study their general diffraction properties by Rigorous Coupled-Wave Analysis (RCWA). Different from traditional Bragg (isotropic) gratings, Bragg PGs are verified to have high diffraction efficiency for large field of view, which is ideal for exit-pupil-expanders in waveguide-based head-mounted-displays, spectroscopy, and fiber-optic telecommunication systems. The RCWA approach allows for a rigorous and accurate solution without paraxial approximations to be obtained with much lower computational cost and time, as compared to finite-element, finite-difference, or analytical coupled-wave approaches. Therefore, it enables the study of the complete transmittance and reflectance behavior of Bragg PGs in the most computationally efficient way. Diffraction characteristics including angular response and polarization sensitivity are investigated. The spectral response and thickness dependence are also examined.

High fructose corn syrup was used for preparation of holographic gratings photosensitized with potassium bichromated, for to analyze the behavior of diffraction efficiency to first order. The behavior of diffraction efficiency to first order was analyzed at time intervals different: 24, 48, 72 and 96 hours, because to the recorded gratings showed instability 24 hours after of record. For this reason, we decided to study in the time the evolution of diffraction efficiency parameter for to determine the maximum modulation of material holographic (HFCS-bichromated). The study realized showed that after of 72 hours, the photosensitized material reaches its maximum modulation, with a diffraction efficiency to first order of 4 percent.

Holographic data storage has large storage capacity and high transfer rate, it becomes one of the next-generation information storage technologies. Bis(2,6-difluoro-3-(1-hydropyrrol-1-yl)phenyl)titanocene (IRG 784) is a good photoinitiator doped in photopolymer, poly(methyl methacrylate) （PMMA）is an excellent choice to making photopolymer with thickness of millimeter range. The solubility of phenanthrenequinone in MMA is a little low, for IRG 784 is very high. In this paper, I use IRG 784 as photoinitiator doped in PMMA made a kind of photopolymer with thickness of millimeter range for holographic data storage. We studied the optical characteristics of IRG 784–doped PMMA photopolymer with different weight ratio of IRG 784 doped. For the preparation of material, we use methyl methacrylate solution as the monomer, azo-bis-isobutyronitrile as the thermo-initiator. The samples with clear optical transmission is orangered. The wavelength of laser for recording and reconstructing we used was 532nm. In the recording process, recording waves interfered for 2 seconds with the cross angle of 60 degrees. After 2 seconds is the reconstruction process, the original reference wave reconstructed the grating for 0.6 seconds. These two processes cycled until the reaction ended. We set the polarization state of signal wave as s-polarization. Both s-polarization and p-polarization as reference wave we used to recording. Through a series of experiments, we can conclude that the weight ratio of IRG 784 dissolved in MMA is significant to increase diffraction efficiency. Although the diffraction efficiency is lower than in traditional holography, our material can be used in polarization holography.

A blind variant of digital holographic microscopy is presented that removes the requirement for a well-characterized, highly divergent reference beam. This is achieved by adopting an off-axis recording geometry where a sequence of holograms is recorded as the reference is tilted, and an iterative algorithm that estimates the amplitudes and phases of both beams while simultaneously enhancing the numerical aperture. Numerical simulations have demonstrated the accuracy and robustness of this approach when applied to the coherent imaging problem.

Computer generated hologram (CGH) is becoming increasingly important for a 3-D display in various applications including virtual reality. In the CGH, holographic fringe patterns are generated by numerically calculating them on computer simulation systems. However, a heavy computational cost is required to calculate the complex amplitude on CGH plane for all points of 3D objects. This paper proposes a new fast CGH generation based on the sparsity of CGH for 3D point cloud model. The aim of the proposed method is to significantly reduce computational complexity while maintaining the quality of the holographic fringe patterns. To that end, we present a new layer-based approach for calculating the complex amplitude distribution on the CGH plane by using sparse FFT (sFFT). We observe the CGH of a layer of 3D objects is sparse so that dominant CGH is rapidly generated from a small set of signals by sFFT. Experimental results have shown that the proposed method is one order of magnitude faster than recently reported fast CGH generation.

Near-to-eye holographic displays act to directly project wavefronts into a viewer’s eye in order to recreate 3-D scenes for augmented or virtual reality applications. Recently, several solutions for near-to-eye electroholography have been proposed based on digital spatial light modulators in conjunction with supporting optics, such as holographic waveguides for light delivery; however, such schemes are limited by the inherent low space-bandwidth product available with current digital SLMs. In this paper, we depict a fully monolithic, integrated optical platform for transparent near-to-eye holographic display requiring no supporting optics. Our solution employs a guided-wave acousto-optic spatial light modulator implemented in lithium niobate in conjunction with an integrated Bragg-regime reflection volume hologram.

Collinear holographic data storage system is a promising candidate for next-generation storage technique. Numerical simulation plays a vital role in the process of revealing physical insight into the effectiveness of proposed methods and providing guidance for further system optimization. In this work, we demonstrated a GPU accelerated numerical model for image formation in collinear holographic data storage system. An average 125 times speedup with 99.8% accuracy was achieved with our accelerated model compared to conventional CPU based simulation. Applications of our model for collinear holographic data storage system such as wavelength drift compensation and noise study were demonstrated.

Wavefront printing for a digitally-designed hologram has got attentions recently. In this printing, a spatial light modulator (SLM) is used for displaying a hologram data and the wavefront is reproduced by irradiating the hologram with a reference light the same way as electronic holography. However, a pixel count of current SLM devices is not enough to display an entire hologram data. To generate a practical digitally-designed hologram, the entire hologram data is divided into a set of sub-hologram data and wavefront reproduced by each sub-hologram is sequentially recorded in tiling manner by using X-Y motorized stage. Due to a lack of positioning an accuracy of X-Y motorized stage and the temporal incoherent recording, phase continuity of recorded/reproduced wavefront is lost between neighboring subholograms. In this paper, we generate the holograms that have different size of sub-holograms with an overlap or nonoverlap, and verify the size of sub-holograms effect on the reconstructed images. In the result, the reconstructed images degrade with decreasing the size of sub-holograms and there is little or no degradation of quality by the wavefront printing with the overlap.

Calculation of the exact diffraction field of a three dimensional object from its samples taken over the entire space can be obtained by defining it as an inverse problem. For that purpose, we propose an algorithm based on L₁-norm minimization to solve the defined inverse problem. Proposed algorithm paves the way to reconstruct the original diffraction field by having less number of samples compared to the methods based on L₂-norm minimization.

In this paper, we investigate quality factors of numerical reconstruction with a small number of signals based on sparsity from a holographic fringe pattern. Holographic fringe pattern generated by Fresnel diffraction is a complex amplitude and sparse distribution in frequency domain. The sparsity of holographic fringe pattern could play a key role in reconstruction quality assessment in compressive holography. In this paper we have investigated sparsity constraint on holographic fringe pattern which influences the overall quality of numerically reconstructed data. In addition, we have investigated reconstruction quality for various subsampling methods including uniform sampling, random sampling, variable density sampling, and magnitude-based sampling. Experiments have been conducted to evaluate reconstruction qualities on sparsity constraints and sampling patterns. Experimental results indicate that the way to extract the sparse signals could significantly affect the quality of the numerical reconstruction in digital holography and visually plausible reconstruction could be obtained with a sparse holographic fringe pattern.

3D imaging is demanding technology required in fluorescence microscopy. Even though holography is a powerful technique, it could not be used easily in fluorescence microscopy because of low coherence of fluorescence light. Lately, several incoherent holographic methods such as scanning holography, Fresnel in coherent correlation holography (FINCH), and self-interference incoherent digital holography (SIDH) have been proposed. However, these methods have many problems to be overcome for practical applications. For example, DC term removal, twin image ambiguity, and phase unwrapping problems need to be resolved. Off-axis holography is a straightforward solution which can solve most of these problems. We built an off-axis SIDH system for fluorescence imaging, and investigated various conditions and requirements for practical holographic fluorescence microscopy. Our system is based on a modified Michelson interferometer with a flat mirror at one arm and a curved mirror at the other arm of the interferometer. We made a phantom 3D fluorescence object made of 2 single-mode fibers coupled to a single red LED source to mimic 2 fluorescence point sources distributed by a few tens of micrometers apart. A cooled EM-CCD was used to take holograms of these fiber ends which emit only around 180 nW power.

We have investigated distortions in the axial position calculations of a sample in lens-free digital inline holography (LDIH). Three-dimensional structure of a sample can be accurately obtained through a series of processes in LDIH, Fourier-domain digital filtering, and numerical focusing. The axial information of a sample is calculated through numerical beam propagation using diffraction theory and can be easily distorted because of approximations and assumptions used in the diffraction formula and the numerical beam propagation analysis used in LDIH. Since the reference light in LDIH is normally a diverging spherical beam from a point source, axial information of a sample calculated by a numerical focusing algorithm with a plane reference beam is off from the real axial position of a sample. We propose an algorithm that can correct this distortion in LDIH.

We propose a method for computing realistic computer-generated holograms (CGHs) of three-dimensional (3D) objects, where we benefit from well-established graphical processing units (GPUs) and computer graphics techniques to handle occlusion, shading and parallax effects. The graphics render provides a 2D perspective image including occlusion and shading effects. We also extract the depth map data of the scene. The intensity values and 3D positions of object points are extracted by combining the rendered intensity image and the depth map (Z-buffer) image. We divide the depth range into several planes and quantize the depth value of 3D image points to the nearest plane. In the CGH computation part, we perform proper Fresnel transformations of these planar objects and sum them up to create the hologram corresponding to the particular viewpoint. We then repeat the entire procedure for all possible viewpoints and cover the hologram area. The experimental results show that the technique is capable of performing high quality reconstructions in a fast manner.

Hypothesis of formation changes on image through photo-physicochemical processes is proposed. For record the holographic grating: [albumin + water + iron ammonium citrate + hv], the photo-crosslinking through transfer of electrons due to ions mobility and radicals in the system. Polarity by charge transfer and the formation of free radicals among atoms and molecules occurs with application of laser He-Cd, λ = 442nm. Photochemical reactions, produces intramolecular bonds. The holographic gratings thickness were 80μm, with diffraction efficiency of 15%.

In this study, angular multiplexing hologram recording photopolymer films were studied experimentally. The films contained acrylamide as a monomer, eosin Y as a sensitizer, and triethanolamine as a promoter in a polyvinyl alcohol matrix. In order to determine the appropriate thickness of the photopolymer films for angular multiplexing, photopolymer films with thicknesses of 29-503 μm were exposed to two intersecting beams of a YVO laser at a wavelength of 532 nm to form a holographic grating with a spatial frequency of 653 line/mm. The diffraction efficiencies as a function of the incident angle of reconstruction were measured. A narrow angular bandwidth and high diffraction efficiency are required for angular multiplexing; hence, we define the Q value, which is the diffraction efficiency divided by half the bandwidth. The Q value of the films depended on the thickness of the films, and was calculated based on the measured diffraction efficiencies. The Q value of a 297-μm-thick film was the highest of the all films. Therefore, the angular multiplexing experiments were conducted using 300-μm-thick films. In the angular multiplexing experiments, the object beam transmitted by a square aperture was focused by a Fourier transform lens and interfered with a reference beam. The maximum order of angular multiplexing was four. The signal intensity that corresponds to the squared-aperture transmission and the noise intensity that corresponds to transmission without the square aperture were measured. The signal intensities decreased as the order of angular multiplexing increased, and the noise intensities were not dependent on the order of angular multiplexing.

Holography has advanced rapidly over the years due to technical melioration in the field of optics. Three-dimensional imaging has gained importance to upgrade the existing imaging and display system. Holography has become one of the branches of optics gaining significant importance with a vast number of technical and industrial applications. When we address holography the first thing that comes to mind is projecting a three dimensional object on thin air. The word holography has always been confused between peppers ghost effect. The famous English phrase “A picture is worth a thousand words”, means a complex idea can be conveyed by a single picture. The basic principle of holography sounds complex with all its technical terms. This paper aims to explain the concept of the CυBE: Coherent υ Beam Educator that contains a transmission hologram illuminated with a laser diode. This paper summarizes the construction details of the CυBE and the optical setup to record the transmission hologram. It also briefs the circuit connections for the laser diode that’s works with an aid of a push button. When viewer presses the push button the original scene is reconstructed. It provides details regarding the angle of reference beam at recording and how the reference beam is compensated at reconstruction. Also this paper highlights how the magnification of the recorded image is affected with respect to the path length of the laser diode inside the box during reconstruction of the recorded hologram.

Page-based holographic data storage (HDS) is very sensitive to disturbances such as tilt and media positioning because of extremely high density of HDS. As a result, reconstructed images are also affected by disturbances, which is represented as degradation of image and signal-to-noise ratio (SNR). Therefore, it is important to detect and compensate the disturbances of HDS. In order to detect and compensate the disturbances, there have been many researches using degradation shapes of reconstructed image. However, it is hard to obtain and analyze the degradation shapes because complex and iterative experiments are required. Furthermore, experiments also have to be done for applying detection and compensation algorithms. Because of inefficiency of experiments, channel model of HDS which can model degradation shapes with respect to disturbances is important. Channel model can reduce the number of experiment and improve efficiency of research. In previous research, channel model of holographic data storage was proposed, but detailed description of the mathematical model and degradation shapes with respect to disturbances direction and amplitude were not modeled. In this paper, advanced channel model which is possible to model degradation shapes is proposed. Proposed channel model considers three causes which effect to media positioning and tilt: Bragg mismatch, imperfect phase conjugation, and media deformation due to temperature. In order to represent degradation of diffraction efficiency caused by Bragg mismatch and media deformation, k-sphere model whose vector concept is expanded to field to use in overall data page with each signal vectors revised by Rodrigues rotation formula is applied.

In this paper we present a lensless transmission digital holographic microscope for the investigation of transparent samples. The setup consists of a laser diode, an object positioned on a cover slip and a CMOS sensor. We use a laser diode for illumination which emits a divergent beam and acts as a point source, so that additional components such as a pinhole are not required. The laser diode is operated below the lasing threshold to decrease the coherence length and thus to reduce speckle noise. Due to the compact and small size of the setup, it requires minimized effort for applications in field operation. The lensless setup was characterized by using an USAF-target for determining the resolution of the system which is 2.2 μm. In the following, transparent or semitransparent samples are investigated. Microstructured plastic samples are placed on the specimen holder and characterized by the holographic microscope. By applying the angular spectrum method on the recorded images, we are able to reconstruct the investigated objects. The in-line geometry of the setup facilitates the simplicity of the setup but also induces optical errors, for instance twin images. Twin images superimpose with the object’s signal and require additional numerical reconstruction algorithms. For reducing the effect of the twin image problem, we apply an iterative phase retrieval algorithm. In the conclusion, we discuss the resolution and quality of the recorded images and evaluate the numerical reconstruction process.

The aim of this study is to determine the effect of monomer diffusion on the photoinduced shrinkage profile in acrylamide based photopolymer layers during holographic recording. Using phase shifting electronic speckle pattern interferometry the displacement at each pixel in the image of the layer is measured. The complete displacement profile of the layer was obtained using phase shifting technique. We observed a reduction in shrinkage as a result of monomer diffusion from unexposed regions of holographic exposure. As a result of diffusion the maximum shrinkage was reduced by 26 % from 7.18μm to 5.28μm in a photopolymer layer of thickness160 ± 3 μm after 84 seconds of recording.

An out-of-plane sensitive electronic speckle pattern interferometer (ESPI) using holographic optical elements (HOEs) for studying rotations and vibrations is presented. Phase stepping is implemented by modulating the wavelength of the laser diode in a path length imbalanced interferometer. The time average ESPI method is used for vibration measurements. Some factors influencing the measurements accuracy are reported. Some advantages and limitations of the system are discussed.

High-definition CGHs can reconstruct high-quality 3D images that are comparable to that in conventional optical holography. However, it was difficult to exhibit full-color images reconstructed by these high-definition CGHs, because three CGHs for RGB colors and a bulky image combiner were needed to produce full-color images. Recently, we reported a novel technique for full-color reconstruction using RGB color filters, which are similar to that used for liquid-crystal panels. This technique allows us to produce full-color high-definition CGHs composed of a single plate and place them on exhibition. By using the technique, we demonstrate full-color CGHs that reconstruct hybrid scenes comprised of real-existing physical objects and CG-modeled virtual objects in this paper. Here, the wave field of the physical object are obtained from dense multi-viewpoint images by employing the ray-sampling (RS) plane technique. In addition to the technique for full-color capturing and reconstruction of real object fields, the principle and simulation technique for full- color CGHs using RGB color filters are presented.

Full-parallax high-definition CGHs composed of more than billion pixels were so far created only by the polygon-based method because of its high performance. However, GPUs recently allow us to generate CGHs much faster by the point cloud. In this paper, we measure computation time of object fields for full-parallax high-definition CGHs, which are composed of 4 billion pixels and reconstruct the same scene, by using the point cloud with GPU and the polygon-based method with CPU. In addition, we compare the optical and simulated reconstructions between CGHs created by these techniques to verify the image quality.

We show preliminary results of holographic diffraction gratings recorded in an emulsion composed of cupric chloride, PVA, and dye extracted from natural pigments of a succulent cactus. We measure the intensity of light diffracted to first order, the curve of the energy of exposure is shown.

Transmission holograms made with egg's albumin, used as a matrix and violet of gentian as dye, and ammonium dichromate as sensitizers. Behavior is outlined of the diffraction efficiency of gratings based on the parameters of exposure energy, and thickness. All the gratings were recorded at line 442 nm of laser He-Cd.

Nopal mucilage potentially has certain properties required for the preparation biofilms which can be used as holographic replication recording medium. In this study, mucilage from nopal was extracted and characterized by its ability to form films under different concentration with polyvinyl alcohol. The transmission holographic diffraction gratings (master) were replicated into nopal films. The results showed good diffraction efficiencies. Mucilage from nopal could represent a good option for the development of films to replication holographic, owing to; its low cost and its compatibility with the environmental.

Digital holography allows to reconstruct information about objects and 3D-scenes. Currently it is widely used in physics and astronomy, medicine, biology, chemistry, and etc. Digital holographic registration is obtained by shooting of interference patterns created by object and reference beams. Using the constructed setup, a number of digital holograms was recorded. Setup allows to record holograms in “transmission” and “reflection” modes of object’s illumination. 3Dscenes depth were ranged from 1 mm to 0.5 m. Distances between elements of 3D-scene and digital camera plane were equal to 0.7÷1.4 m. Results of numerical reconstruction of sections of registered 3D-scenes are presented.

Applications of optical methods for encryption purposes have been attracting interest of researchers for decades. The first and the most popular is double random phase encoding (DRPE) technique. There are many optical encryption techniques based on DRPE. Main advantage of DRPE based techniques is high security due to transformation of spectrum of image to be encrypted into white spectrum via use of first phase random mask which allows for encrypted images with white spectra. Downsides are necessity of using holographic registration scheme in order to register not only light intensity distribution but also its phase distribution, and speckle noise occurring due to coherent illumination. Elimination of these disadvantages is possible via usage of incoherent illumination instead of coherent one. In this case, phase registration no longer matters, which means that there is no need for holographic setup, and speckle noise is gone. This technique does not have drawbacks inherent to coherent methods, however, as only light intensity distribution is considered, mean value of image to be encrypted is always above zero which leads to intensive zero spatial frequency peak in image spectrum. Consequently, in case of spatially incoherent illumination, image spectrum, as well as encryption key spectrum, cannot be white. This might be used to crack encryption system. If encryption key is very sparse, encrypted image might contain parts or even whole unhidden original image. Therefore, in this paper analysis of security of optical encryption with spatially incoherent illumination depending on encryption key size and density is conducted.