This PDF file contains the front matter associated with SPIE Proceedings Volume 10558, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Optically indistinguishable copies of 3D real objects or holograms are known to be suitable to replace exhibited artistic pieces in museums. In this paper, we discuss holography as an alternative to protect, share and preserve finely crafted gold pieces belonging to the indigenous treasure inherited by Colombians. We present high diffraction efficiency monocolor and color holograms of native goldwork. As reference objects and proof of concept, we use replicas of the renowned and emblematic Poporo Quimbaya, pre-Hispanic gold pendants and anthropomorphic gold pieces. We report experimental details to deal with different types of commercial holographic recording materials, as for example, PFG-03M and PFG- 03C silver halides or C-RT20 photopolymers. And its general feasibility for reproducing high-quality holograms suitable for museum exhibitions or traveling art-collections.

In the astronomical field, the progressive increase in telescope size and in the complexity of the spectroscopic instrumentation has highlighted how the current technologies and traditional materials for dispersing elements do not completely meet the present and future requirements. Therefore, new materials and solutions have to be developed, not only to realize future astronomical facilities, but also to improve the performances of already available instruments and devices. In this context, the use of photopolymeric materials for the production of Volume Phase Holographic Gratings (VPHGs) is becoming an interesting approach thanks to their key properties, in particular the self-developing, high sensitivity and the simple manufacturing process. Here, the main design parameters and the strategy to address them will be presented considering the whole UV-NIR spectral range showing the actual capabilities together with the results obtained on real observing astronomical facilities.

Within the astronomical field, many focal-reducer spectrographs that are currently available at state-of-the-art telescopes facilities, would benefit from a simple refurbishing that aims to increase both the resolution and spectral range. This kind of upgrade would cope with the progressively challenging scientific requirements, but, in order to make it appealing, it should minimize the changes in the existing structure of the instruments. In the past, many authors already tried to propose solutions based on stacking subsequently many dispersive elements and recording multiple spectra in one shot (multiplexing). Although this idea is very promising, it brings several drawbacks and complexities that prevent the straightforward integration of such a device in a spectrograph. Fortunately, today, the situation has changed dramatically, thanks to the availability of new materials such as the photopolymeric holographic films, that have proven their reliability in the fabrication of volume-phase holographic gratings (VPHGs) for astronomy. Thanks to the various advantages made available by these materials in this context, we propose an innovative solution for designing stacked multiplexed VPHG that is able to secure efficiently different spectra in a single shot. This will allow to increase resolution and spectral range enabling astronomers to greatly economize their awarded time at the telescope. In this proceeding, we demonstrate the applicability of our solution, both in terms of expected performance and feasibility, supposing the upgrade of the Gran Telescopio CANARIAS (GTC) Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS).

Digital holographic microscopy (DHM) is an established technique for the investigation of biological samples and very promising for non-destructive testing. As DHM is an optical metrology technique it enables a non-contact, non-destructive and fast measurement which can be used for material characterization and quality control. DHM provides amplitude and phase information which originate from optical path differences and refractive index changes of the material, thus it is able to measure topographic structures. Especially the non-destructive inspection of buried or capped structures such as microelectromechanical systems (MEMS) is still challenging, due to the absorption in the covering layer and interference of light between the different layers. In this paper we present a common-path digital holographic setup for the investigation of reflective samples. By choosing a wavelength at which the covering layer is transparent, laser light can pass this surface. Furthermore, we employ a coherence gating effect utilizing a laser diode below threshold with reduced temporal coherence to diminish speckle patterns and to suppress interference between the layers. At the same time the spatial coherence remains high which improves the image quality. Using the angular spectrum method and a quality guided phase unwrapping algorithm, we successfully reconstruct 3D images of buried structures. In addition Zernike polynomials reduce the effect of wave distortions within the setup. Overall a lateral resolution of about 1.5 μm can be achieved.

This paper presents an update of the traditional museographic diorama, with the addition of a full-color H2 analog hologram. It explains how it works, and indicates the benefits for museums. Unlike the Denisyuk color technique where the final image appears completely behind the surface of the hologram, the H2 hologram is a transplane image. To realize this new kind of diorama, an ultra-realistic "transplane" color hologram is recorded with the Ultimate holographic material and blends into a real three-dimensional scene where the viewer no longer knows where the real ends and where the virtual begins. The play of the hologram’s lighting makes possible the objects appear or disappear in the decors and interact with the public. The result boosts the little outdated traditional diorama and meets the expectations of a modern audience interested in mixed reality.

Studies have reported that propagating waves can be generated in a finite one-dimensional structure by using two piezoelectric actuators. However it is not easy to generate stable and continuous propagating waves due to the finite boundaries. Driving two piezoelectric actuators at two different locations with sinusoidal signals of 90° phase difference, the propagating waves can be generated on a one-dimensional structure. However, the correlation between the actuators and propagating waves is still not clear. In this paper, we adopt shadow Moiré technique to monitor the full-field out-of-plane deformation response of the generated propagating waves in the one-dimensional (1-D) plate with 180 mm in length. A 200-μm-pitch grating was used in this moiré interferometry setup. The moiré fringe images were captured by a high dynamic camera sequentially. Moiré fringes were analyzed by regions of interested (ROI) capturing technique and Fourier transform to retrieve phase information, which included 1-D plate deformation. After the phase was unwrapped and filtered, the instantaneous surface profile was reconstructed. Our experimental results demonstrated that our system can capture propagating waves generated by using the second (60.025 Hz) and the third (109.500 Hz) resonant modes.

Head-up-displays (HUD) and head-mounted-displays (HMD) have in common to utilize an optical combiner for electronic image creation in a see-through optical setup. Volume holographical optical elements (vHOE) appeal to system designers by their lightweight, thin film construction that also enables concepts to integrate those into lens or windshield manufacturing. vHOEs can be customized towards optical system requirements through their adaptable angular and spectral Bragg selectivity, while also diffraction efficiencies can be widely chosen to meet the overall optical specifications. Photopolymer films (Bayfol® HX film) have been recently introduced into the market place and prove themselves as easy to process materials. In this paper we investigate the impact of incoherent pre-exposure, which is a technique that can be used to overcome oxygen inhibition in a very convenient way. Incoherent light also can be used to reduce the dynamic range of the photopolymer film to fine tune diffraction efficiency and reduce over-modulation of transmission HOEs. Another interesting aspect is to minimize coherent media scatter that can occur at long exposure times. So reduction of the overall applied coherent light dosage is the key here. Incoherent pre-exposure therefore should be considered as an integral part of a holographer’s toolset to perfect the recording results for vHOEs.

This paper reports experiments that confirm Belloni (2003) that pre-soaking a silver halide holographic emulsion in a dilute solution of the formate ion (HCO2-) will hypersensitize the emulsion by a factor of 5xs to 10xs, depending on the timing of development post-exposure. The quantum efficiency of the emulsion is effectively 1 in the first case. The extremely fine grain size of the holographic emulsion (Slavich PFG-01) is maintained and holographic image quality is excellent. When combined with a TEA pre-soak the expected TEA color shift is maintained.

Holographic photopolymers capable of high refractive index modulations (Δn) on the order of 10^-2 are integral for the fabrication of functional holographic optical elements (HOEs) for use in a range of optical applications. A novel high refractive index liquid writing monomer suitable for two-stage photopolymer systems was designed and synthesized. This monomer exhibits facile synthetic procedure, low viscosity, high refractive index as well as excellent solubility in a low refractive index urethane matrix. The solubility limit, refractive index change and reaction kinetics/conversion were studied against a commercial reference high refractive index monomer, 2,4,6-tribromophenyl acrylate (TBPA). Superior performance in solubility to TBPA is shown with similar reaction kinetics and final conversion as confirmed by realtime Fourier transform infrared spectroscopy (FTIR) and real-time monitoring of diffraction grating growth. We demonstrate the ability to load substantial amounts of these writing monomers enabling a straightforward path to higher achievable Δn values (peak-to-mean Δn ~ 0.03) without sacrificing optical properties (transparency, color or scatter) as validated through recording ~100% efficiency volume transmission holograms in sub-15 μm thick films.

New embossed hologram originating technique, producing effects which are not possible to reproduce with commonly used image-matrix Kinemax type equipment was developed. Thus, Geola Digital Ltd. is launching a series of unique equipment devoted to embossed holograms originating. Equipment allows one to produce master-holograms containing simultaneously achromatic and true colour deep 3D images. Such images are perfectly viewable while illuminated with light sources situated in front of the hologram or at its back. The Originators also can produce and with higher precision all effects achievable with commonly used image-matrix originators. Therefore, an ultimate goal to have one Originator assuring all security features from Level 1 to Level 4 is achieved. Moreover, pulsed laser employed in Geola's originators enable one to produce whole holograms windows quickly, employing an optical holograms recombination instead of mechanical one.

Image quality of the computer-generated holograms are usually evaluated subjectively. For example, the reconstructed image from the hologram is compared with other holograms, or evaluated by the double-stimulus impairment scale method to compare with the original image. In previous research, we proposed image quality evaluation by peak signal-to-noise ratio and diffraction efficiency. Theory and numerical experimental results are shown on Fourier transform transmission hologram of both amplitude and phase modulation. In this paper, we compare objective evaluation method and subjective evaluation and verify validity. Subjective evaluation is performed by optical and numerical reconstructions, and objective evaluation is performed by the structural similarity index and diffraction efficiency.

Synthetic holograms have achieved a great impact in a variety of fields like architecture, advertising, army and art, and have proven their importance in advancing the holographic displays as visual communication media. Printing synthetic holograms needs the development of a holographic printer that from a set of 2D images allows to create 3D holographic images of real objects and computer generated objects. With the purpose of developing a holoprinter, we have implemented three related components: i) design and implementation of an optical system for direct writing of hogels, ii) a computational implementation to generate parallax 2D images and finally, iii) the implementation of an opto-mechanical and control system for automatic recording of the synthetic holograms. The three components have been developed under the restricted conditions of our holographic laboratory. In this way, a direct write optical setup was implemented using He-Ne laser, and an optical system for hogel writing with a field of view (FOV) of 60° was designed by using commercial lenses. To generate 2D parallax images, an application was created in the free computer graphics software Blender, applying different camera configurations. And a LabView application was made to automatically control obturation and displacement of the holographic plate. The system developed can record computer generated objects and real objects. Real objects are digitized by using a conventional photographic camera. Reflection full parallax holographic stereograms were recorded on PFG-01 plates and their holographic reconstructions are presented and discussed.

We propose a vision-based position sensor based on Digital Holography (DH) for in-plane and out-of-plane displacements measurement of a patterned plate with sub-pixel resolutions. DH is a lensless imaging principle using solid-state camera and/or spatial light modulators (SLM). Object scenes are generated or reconstructed numerically through wave propagation computations applied to a diffracted optical field recorded as an interferogram. The application of visual positioning to manipulation tasks in micro-robotics requires high accuracy and wide ranges of displacements that, unfortunately, are limited by finite depth-of-focus and fixed working distance of refractive imaging systems. Recently, we demonstrated that DH allows in-plane positioning of mobile targets ensuring nanometer resolutions at diverse working distances within a continuous range of more than 15 centimeters. By recording a set of digital holograms of a pseudo-periodic pattern fixed onto a moving target, images in phase and in intensity are restored by numerical reconstruction using Angular Spectrum Propagation methods by adjusting the reconstruction distance. A last step consists in performing a direct phase measurements of periodic pattern to reach nanometer resolutions. Three 2DFFT are required at minimum to extract the pattern position, which is time consuming if several hundred of holograms are recorded. We explore a new approach that consists to restore in-plane / out-of-plane position directly from the 2DFFT of the digital hologram without any need for image restitution. The proposed vision-based position sensor combines a 10 Mp CMOS camera and a SLM in order to perform a fine control of the interferometer reference arm.

Pixelation, blur and additional noise of imaging system limit the resolution of final images acquired. Many pixel superresolution algorithms have been applied to enhance the resolution of imaging system by merging a sequence of lowresolution holograms with different type of imaging system, for example by shifting illumination source or using wavelength scanning. Most of these pixel super-resolution imaging systems can only be implemented to single-layer sample. For multi-layer imaging system and volumetric imaging scenarios, the relative displacement of various sample at different layers will disturb each other. Herein, we report a portable, cost-effective, lensless wide-filed digital in-line holographic microscopy imaging system based on in-line hologram segmentation and pixel super-resolution algorithm, which can separate target sample from the background and improve the resolution of the sample. We demonstrated the effectiveness of our system with numerical simulation and experiment with volumetric sample. In numerical simulation, we applied a very simple two-layer sample model that samples in two layers have various moving speed and directions and also did the volumetric imaging experiment with cuvette containing algae floating in. In our system, the sensor captured a sequence of low-resolution diffraction patterns. The target sample mix with background disturbance, which will invalidate the direct pixel super-resolution technique. We applied segmentation algorithm to the reconstructed images from holograms, separating target sample from background and generating a sequence of sub-images containing only target sample with same resolution and numerical aperture as original holograms. Finally the enhanced resolution reconstructed image of target sample was obtained with pixel super-resolution algorithm, which can go beyond pixel limitation and get sub-pixel perspective microscopy. This imaging system has the advantages of wide-field, portable and lensless.

A hologram of a scene can be digitally created by using a large set of images of that scene. Since capturing such a large amount is infeasible to accomplish, one may use view synthesis approaches to reduce the number of cameras and generate the missing views. We propose a view interpolation algorithm that creates views inside the scene, based on a sparse set of camera images. This allows the objects to pop out of the holographic display. We show that our approach outperforms existing view synthesis approaches and show the applicability on holographic stereograms.

We have previously introduced a monolithic, integrated optical platform for transparent, flat-panel holographic displays suitable for near-to-eye displays in augmented reality systems. This platform employs a guided-wave acousto-optic spatial light modulator implemented in lithium niobate in conjunction with an integrated Bragg-regime reflection volume hologram. In this paper, we depict analysis of three key system attributes that inform and influence the display system performance: 1) single-axis diffraction-driven astigmatism, 2) strobed illumination to enforce acousto-optic grating stationarity, and 3) acousto-optically driven spatial Nyquist rate.

A single SLM full-color holographic 3-D display based on sampling and selective frequency-filtering methods is proposed. Sampled R, G and B-holograms provide periodic 3×3 arrays of their frequency spectrums. By allocating three groups of three spectrums to each color hologram, and selectively filtering out those spectrums with their own spectrum filtering masks, frequency-filtered R, G and B-holograms can be obtained. These holograms are then multiplexed into a single hologram and reconstructed into a full-color 3-D image on a 4-f lens system. With the Fourier-optical analysis and experiments with 3-D objects the feasibility of the proposed system is finally confirmed.

The liquid crystal spatial light modulator is able to provide flexible wavefront modulation, whereas its nonlinear and spatial varying phase response will influence the modulation accuracy. In this paper, a software based C++ algorithm are designed to calibrate these distortions regionally. Twyman-Green interference method is utilized for gray versus phase shift measurement. The curvature of cover glass is measured by phase shift algorithm. Finally the entire panel is divided into several local regions to overcome the spatial varying phase response. For each sub-region, the nonlinear phase response is calibrated by remapping table. For a Jasper 4K SLM panel, when three local regions are built, the root mean error of linear phase shift is reduced to approximate 0.1 rad. The calibrated SLM is applied for holographic display and the improvement ratios of structural similarity index reach 30.6%, 62.5%, and 43.6% for R, G, and B reconstructed components respectively.

Comparative analysis between gratings registered in cupric chloride and cupric chloride films, with synthetic dye is presented. Preliminary results of recorded holographic diffraction gratings are shown, in which the polyvinyl alcohol mixed with a photosensitizing agent, cupric chloride and synthetic dye. The gratings were recorded using laser diode at a wavelength of 445 nm. Experimental results of gratings registered with cupric chloride and synthetic dye showed higher diffraction efficiency than those registered in cupric chloride.

Space bandwidth product (SBP) is one of the most significant limitation for displaying the digital holographic display. Due to the SBP problem, the size and viewing angle of displayed holograms cannot be enlarged simultaneously. To overcome the SBP problem, holographic projection system has been researched. It uses a field lens to converge diffracted light from a spatial light modulator (SLM) into a viewing window, where the observer can see whole hologram image displayed on the SLM. However, it has a problem that the viewing distance between the display and observer cannot be controlled and fixed on the viewing window plane. We propose a method to control the position of viewing window formation in the holographic projection system by using an electrically focus tunable lens. We added the focus tunable lens in the holographic projection system, and the position of the viewing window can be controlled by its lens power variation. The principle of controlling viewing window in the proposed system is described, and the relationship among the optical power of focus tunable lens, location and size of the viewing window is analyzed. A computer generated hologram encoding based on Fresnel diffraction theory is developed to generate hologram contents for the proposed system with consideration of varying optical power of the focus tunable lens. Test-bed is built to verify the feasibility of the proposed method, and the experimental results confirm that the proposed method can effectively control the viewing window position of the holographic projection system.

A theoretical study of gratings with radial symmetry and variable periods with sinusoidal profile, modulated for amplitude are shown. The behavior of the diffraction pattern and their symmetry degree of gratings were observed. Grating period can be modulated by external factor as spatial orientation effects per propagation, as inclination perspective of image projections that can produce local modified periods; this modulation kind causes changes in the diffracted pattern orders.

Binary patterns has its origins in the first holograms generated by computer but with the improvement of the computational equipment began to work in gray levels. Binary patterns implementation is a proposal to obtain binary holograms representation without having to modify the techniques for their calculation.

Based on printing techniques, its sought to substitute each hologram pixel for an arrangement of certain size, trying to simulate the original value with a density of binary values. In this way a direct relationship between the arrangement size and the number of values that can be simulated is obtained.

Finding the appropriate arrangement size, its important to establish which shape or pattern will be used. In this theme some variants are proposed, however we highlight the random patterns, showing very interesting properties. Because of this, a small study is carried about propagation of randomness and its effects on the reconstructed field.

Digital holography is a popular technique for investigation of changes of objects parameters: shape, density, temperature, and etc. Speckle noise, twin image, zero order, digital camera's temporal noise and fixed pattern noise (FPN) limit quality of images reconstructed from digital holograms. FPN is the only problem that actually was not researched. In this work effect of digital camera's FPN on reconstructed images is investigated. Characteristics of CCD and CMOS cameras of different types were used: scientific camera, video-surveillance camera, and others. Results of numerical reconstructions from holograms with different FPN are presented. Signal-to-noise ratios are obtained for the reconstructed images.

We propose a new optical secret key sharing method based on the modified Diffie-Hellman key exchange protocol required in cipher system. The proposed secret key sharing algorithm is optically implemented by 2-step quadrature phase-shifting digital holographic encryption technique using orthogonal polarization. An unknown user’s private key is encrypted into three ciphered digital holograms which are supposed to be opened to the public for secret key sharing. The encrypted digital holograms are Fourier transform holograms and are recorded on CCDs with 256 gray level quantized intensities in the optical setup. The decryption with three ciphered digital holograms reconstructs each user’s private key information, which is used to generate the same shared secret key to each other. The advantage of the proposed method is that the optical setup has a kind of double key encryption scheme and provides the discretion of the user’s private key. The proposed method is very efficient in applying to a secret key sharing cryptosystem with high security strength.

Kinoform is a synthesized phase diffractive optical element which allows to reconstruct image by its illumination with plane wave similarly to hologram. All iterative methods of kinoform synthesis use random phase distribution at start as first approximation of future kinoform. Faster convergence and lower synthesis error can be achieved if in place of random phase distribution computer synthesized phase hologram is used. However, this leads to necessity of spatial separation of first and minus first diffraction orders. Results of experiments on kinoform synthesis using phase Fourier hologram as basis for iterative algorithm and comparison with basic technique are presented.

The majority of liquid crystal amplitude spatial light modulators (SLM) in addition to amplitude modulation also produce phase modulation. This additional phase shift depends on a signal value addressed to each SLM pixel. Knowledge of additional phase shift is often necessary for coherent optical systems design. If dependency of phase shift on signal value is known, then the accounting for this additional phase shift during experiments is possible. The results of phase shift measurements of HoloEye LC 2002 SLM, performed by a dual-beam interferometric method are presented. The processing method is based on summation of lines of images of interferometric fringes. Maximum phase shift value detected in experiments was about 0.6π. It was observed with signal value equal to 219. The measurement error is about 0.05π. Implemented techniques can also be used for other amplitude and phase SLMs. The results of using measured dependency of phase shift on signal value in invariant coherent optical correlator design to decrease pattern recognition errors by addition of phase to the output correlation filter in order to compensate for undesired SLM phase shift are presented.

In this paper, a transmission-type full-color holographic screen based on VHOEs is newly proposed, and with which a new type of augmented-reality projection display is implemented. For this, a two-stage diffraction method with two kinds of VHOEs is proposed for the effective removal of color dispersion and DC component. That is, the 1st VHOE for removing color-dispersion is recorded at the angle cutting 60° in half and 2nd VHOE for displaying the full-color image is recorded at the angle of 30°. Then, a projection display system to reconstruct the full-color image without color dispersion and DC component is optimally designed and implemented just by controlling the angles of the LCD display panel and VHOEs, as well as the distance between the two VHOEs. With experiments, the image clarity depending on the focus of the eyes as a space-projection system, as well as the degree of removal of the color dispersion, has been discussed. In addition, successful experimental results confirm a possibility of implementing the VHOE-based full-color augmented-reality projection display system.

Polyvinyl Alcohol (PVA) is used as a polymeric matrix in different mixtures, which are employed to make of holographic, recording films. In this research, three grades of polyvinyl alcohol (PVA) namely fully hydrolyzed and partially hydrolyzed and technical where studied with the aim of determining the influence of PVA degree of hydrolysis on the diffraction efficiency. Therefore, we show preliminary results of holographic diffraction gratings recorded in films were made with PVA and Iron (III) Chloride.

In acrylamide-based photopolymer films, holographic recording processes can be characterized by “polymerization time” and “diffusion time.” Our films contain acrylamide (monomer), triethanolamine (radical initiator) and methylene blue (dye sensitizer) in a polyvinyl alcohol matrix for holographic recording by a He-Ne laser at 633 nm. In this study, diffraction-efficiency growth during holographic recording and angular response of diffraction efficiency after recording were measured. There were nine holographic samples with moderate index modulation and eight samples with overmodulation. Polymerization and diffusion times were determined from the measured diffraction-efficiency growth by curve fitting based on the first-harmonic diffusion-based model. In the curve fitting, film thickness estimated from the measured angular response was used. The evaluated polymerization time ranged between 2.8 to 6.8 sec, and no difference between the two types of index modulation was observed. On the other hand, diffusion time ranged between 3.7 to 35.8 sec, and was found to be clearly dependent on the resultant index modulation of the recorded films. Moreover, both times were found to be slightly dependent on film thickness.