This PDF file contains the front matter associated with SPIE Proceedings Volume 8644, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

In this paper we derive the underlying equations for real time holographic interferometry through selfdiffraction, and demonstrate experimentally on how to employ the different Bragg and non-Bragg diffraction orders to perform one shot determination of the phase deformation, or equivalently, the depth information of a deformed object. We also show that the various diffracted orders may be phase shifted with respect to each other with a constant phase shift which depends on the phase mismatch and the length of the recording material. This technique can therefore have an obvious advantage over traditional phase-shifting holography due to the elimination of the piezo-shifted mirror (inducing the different phase shifts) which limits the traditional technique to slow deformations.

Holographic three dimensional (3D) parallel lithography using femtosecond laser pulse were demonstrated in this paper. A computer generated hologram (CGH) that calculated using kinoform algorithm with optimal rotation angle (ORA) method were used in order to increase the uniformity of the diffraction peaks so that the resolution of the 3D image also improved. The use of femtosecond pulse duration of a Ti:sapphire laser improved the holograms resolution due to larger peak powers that generate larger photonics concentrations at the beam focus and improve single-shot processing. A digital instrument nanoscope was used to verify the result and scanning electron microscopy (SEM) will be used to observe the detail result.

We present a new method for phase stabilization of a holographic recording system for volume Bragg gratings. The primary feature of this method is that it is extremely flexible and simple to integrate into an existing holographic recording setup. The setup allows for Bragg gratings with arbitrary tilt and resonant wavelength to be recorded. An analysis of the effects of phase stabilization and a method for analyzing the effectiveness of this phase stabilization approach are also introduced and successfully demonstrate its benefits.

Beam shaping is important technique to improve holographic and interferometric technologies, and refractive field mapping beam shapers like piShaper demonstrate strong capabilities in increasing predictability and reliability as well simplifying the realization of the mentioned technologies. Most often the piShaper are implemented as telescopic systems with collimated beams at entrance and exit. At the same time the fiber-coupled TEM00 laser sources become more popular in holography and interferometry because of their high beam quality, reduced high frequency noise due to spatial filtering in a TEM00 fiber and convenience in usage. Therefore, the beam shapers should be compatible with those fiber-coupled lasers featured with high beam divergence. Basic piShaper design principles allow to implement a system combining the functions of beam shaping and collimation, as result divergent Gaussian laser beam from TEM00 fiber is transformed, almost lossless, to collimated flattop beam with low divergence, flat wave front, extended depth of field, reduced noise; such a beam is optimum for SLM-based technologies of CGH, Dot-Matrix mastering of security holograms, multi-colour Denisyuk holography, holographic data storage, holographic projection, lithography, interferometric techniques of Volume Bragg Gratings recording, periodic structuring, etc. Achromatic design of the telescopic and collimating beam shapers allows working with several laser sources with different wavelengths simultaneously that is, for example, important in multi-colour Denisyuk holography. This paper will describe some design basics of collimating refractive beam shapers of the field mapping type and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

The Direct Write Digital Holography (DWDH) technique has been used to print master-original holograms for embossed applications using a 440nm pulsed laser. Holograms were recorded on both Silver Halide photo-plates and Shipley photoresist photo-plates. Shipley photoresist consistently exhibited a sensitivity to pulsed radiation several times better than that observed on exposure to CW radiation. In addition, image quality of the recorded holograms using pulsed radiation appeared very similar to that obtainable with CW exposure. The clear implication is that pulsed lasers emitting at 440nm can replace the CW HeCd lasers currently used for the origination of embossed holograms. Master-original holograms recorded with the DWDH technique are able to record deep 3D imagery. The origination technique described allows the production of master-original holograms with achromatic or full colour images. In addition the DWDH technique allows one to combine achromatic and full colour images on one hologram. As a proof of concept, embossing matrix shims were produced from our master-original holograms and embossed holograms were stamped.

The effect of aberrations present in the recording beams of a holographic setup is discussed regarding the period and spectral response of a reflecting volume Bragg grating. Imperfect recording beams result in spatially varying resonant wavelengths and the side lobes of the spectrum are washed out. Asymmetrical spectra, spectral broadening, and a reduction in peak diffraction efficiency may also be present, though these effects are less significant for gratings with wider spectral widths. Reflecting Bragg gratings (RBGs) are used as elements in a variety of applications including spectral beam combining1,2, mode locking3,4, longitudinal and transverse mode selection in lasers5,6, and sensing7,8. For applications requiring narrow spectral selectivity9, or large apertures10, these gratings must have a uniform period throughout the length of the recording medium, which may be on the order of millimeters. However, when using typical recording techniques such as two-beam interference for large aperture gratings and phase-mask recording of fiber gratings, aberrations from the optical elements in the system result in an imperfect grating structure11-13. In this paper we consider the effects of aberrations on large aperture gratings recorded in thick media using the two-beam interference technique. Previous works in analyzing the effects of aberrations have considered the effects of aberrations in a single recording plane where the beams perfectly overlap. Such an approach is valid for thin media (on the order of tens of microns), but for thick recording media (on the order of several millimeters) there will be a significant shift in the positions of the beams relative to each other as they traverse the recording medium. Therefore, the fringe pattern produced will not be constant throughout the grating if one or both beams have a non-uniform wavefront. Such non-uniform gratings may have a wider spectral width, a shifted resonant wavelength, or other problems. It is imperative therefore to know what the effects of aberrations will have on the properties of the RBGs. Thus, in this paper we consider the imperfect fringe pattern caused by the recording beams and its effect on the diffraction efficiency and spectral profile of the recorded reflecting volume Bragg gratings.

We have developed a full-color full-parallax digital 3D holographic display system by using 24 physically tiled SLMs, an optical scan tiling approach and two sets of RGB lasers, which could display 378-Mpixel holograms at 60 Hz, with a displayed image size of 10 inch in diagonal. In this paper, we will review and compare three different holographic display systems developed by our group from various aspects, including SLMs, lasers, optics designs, hologram computation, data transmission, and system synchronization. We will also discuss the bottlenecks and prospects of further development of the system for practical applications.

Electronic holography technology is expected to be used for realizing an ideal 3DTV system in the future, providing perfect 3D images. Since the amount of fringe data is huge, however, it is difficult to broadcast or transmit it directly. To resolve this problem, we investigated a method of generating holograms from depth images. Since computer generated holography (CGH) generates huge fringe patterns from a small amount of data for the coordinates and colors of 3D objects, it solves half of this problem, mainly for computer generated objects (artificial objects). For the other half of the problem (how to obtain 3D models for a natural scene), we propose a method of generating holograms from multi-view images and associated depth maps. Multi-view images are taken by multiple cameras. The depth maps are estimated from the multi-view images by introducing an adaptive matching error selection algorithm in the stereo-matching process. The multi-view images and depth maps are compressed by a 2D image coding method that converts them into Global View and Depth (GVD) format. The fringe patterns are generated from the decoded data and displayed on 8K4K liquid crystal on silicon (LCOS) display panels. The reconstructed holographic image quality is compared using uncompressed and compressed images.

Digital holography made it possible to capture and reconstruct holograms in a computer environment. In a conventional CPU, the real-time reconstruction is not possible when the size of the holograms increase to several mega-pixels range. However, a graphics processor can provide the required computational power. The rapid developments in commercial graphics card technology provide an opportunity to process large blocks of data in a very short amount of time which reduces the hologram reconstruction time significantly. In this manuscript, basics of GPU programming for hologram reconstruction is introduced, and the efficiency of CPU and GPU implementations of the three reconstruction algorithms (Fresnel transformation, angular spectrum method, convolution with free space propagation) are compared. Experimental results indicate that, on average, 100 fps reconstruction rate is achieved with all methods.

Digital holography allows the acquisition of 3D profiles of objects. Digitally captured holograms are reconstructed at the respective distances of the objects to reveal the phase and the intensity profiles. However, computing an object’s 3D profile with only a single reconstruction requires prior knowledge of the distance of the object from the camera. Otherwise, by performing several reconstructions at different distances and by evaluating each image with sharpness estimation, one can determine the in-focus distance of the object. Moreover, it is not practical to perform several reconstructions in real-time systems since reconstruction is the most computationally heavy part in digital holographic imaging. In this paper, we compare common sharpness functions applied to digitally recorded holograms for autofocus algorithms found in the literature. In addition, we show that automatic focus distance search can be done in real-time with scaled-down holograms obtained from the original hologram. This new method improves the speed of autofocus algorithms on the order of square of the scaling ratio. We show that numerical simulations and experimental results are in good agreement.

In CGH, peculiar rendering techniques are necessary to express realistic 3D images because CGHs have parallax. We have proposed the calculation method with the ray tracing method that expresses the hidden surface removal, shading and so on. However, resolutions of current output devices are not high enough to display CGH, so the size of reconstructed images is restricted and viewing zone and visual field are very narrow. To enlarge the size of reconstructed images, the Fourier transform optical system is used. Then we introduce the technique to apply calculation method of CGH with ray tracing method to the Fourier transform optical system in this paper. The Fourier transform optical system reverses the depth of images and reconstructs pseudo stereoscopic 3D images in front of a hologram. We solved this problem by reconstructing images at the back of hologram plane and observing conjugate images. Moreover, we conducted elimination of unnecessary light including 0-th order light. We conducted optical reconstructions that show proposed method is able to make realistic CGHs implementing the hidden surface removal in the Fourier transform optical system.

A hologram display technique that provides speckle-free and shaded reconstructed images is proposed. A three-dimensional (3D) object is composed of object points, which are divided into multiple object point groups displayed in a time-sequential manner. In each object point group, an array of object points are sparsely separated, so that interference does not occur between them. Each object point group is generated by displaying a two-dimensional (2D) array of zone plates on a high-speed spatial light modulator (SLM). The amplitude distribution of the zone plates is modulated two-dimensionally to control the angular intensity distribution of light emitted from the object points to shade reconstructed images. The SLM generates multiple binary images illuminated by different light powers to represent 2D modulated zone plates in a time-sequential manner. A Digital micromirror device (DMD) was used as the high-speed SLM. The resolution was 1,024 × 768, and the frame rate was 22.727 kHz. Each object point group consists of 16 × 24 object points. The reconstructed image consists of 16 × 8 object point groups to obtain a total of 256 × 192 object points. Eight binary images represented each object point group. The frame rate for 3D image generation was 22.2 Hz.

The pixel count of hologram for a holographic 3D display system increases rapidly with the increase in reconstructed object size and viewing angle. According to our analysis, for 10 inch reconstructed object size with 5° viewing angle, a hologram with a pixel count of 378 Million is required. Such a large pixel count is a challenge for both hologram computation and hologram data transmission. The computation load is analyzed to be a few hundreds of Tflop for the object with a few million object points, and the hologram data transmission rate required is analyzed to be 22.3 Gbps and 67.0 Gbps for monochrome display and color display using time division multiplexing at 60 Hz, respectively. A computer cluster with 32.7 Tflops GPU computing ability and 60 Gbps transmission bandwidth was built to meet the hardware requirements for large-pixel-count hologram computation and transmission. A distributed computation method was implemented for computing large-pixel-count holograms. Computation time of 5.6 seconds was achieved for 378- Mpixel hologram containing information of 1.7 M object points. During the playback of holographic video using our holographic 3D display system, the hologram data was read out from SSDs, transmitted over the high speed network, and finally launched onto SLMs for reconstruction. A data transmission rate of 31.8 Gbps was achieved, which corresponded to 378-Mpixel hologram at 84 Hz for monochrome reconstruction and full color reconstruction using space division multiplexing. The increasing demand for computation power and data transmission rate of large-pixel-count hologram video displays has been effectively addressed.

A fast technique to calculate computer-generated holographic stereograms is proposed. We assume that the three-dimensional image generation by holographic stereograms might be similar to that by multi-view autostereoscopic displays; multiple parallax images are displayed with rays converging to corresponding viewpoints. Therefore, a wavefront whose amplitude is the square root of an intensity distribution of the parallax image and phase is a quadric phase distribution of a spherical wave converging to the viewpoint is considered. Multiple wavefronts are calculated for multiple viewpoints and are summed up to obtain an object wave. The proposed technique was verified experimentally.

We have previously introduced an architecture for updatable photorefractive holographic display based around direct fringe writing of computer-generated holographic fringe patterns. In contrast to interference-based stereogram techniques for hologram exposure in photorefractive polymer (PRP) materials, the direct fringe writing architecture simplifies system design, reduces system footprint and cost, and offers greater affordances over the types of holographic images that can be recorded. In this paper, motivations and goals for employing a direct fringe writing architecture for photorefractive holographic imagers are reviewed, new methods for PRP exposure by micro-optical fields generated via spatial light modulation and telecentric optics are described, and resulting holographic images are presented and discussed. Experimental results are reviewed in the context of theoretical indicators for system performance.

True color reflection holograms can be successfully recorded by exposing panchromatic holographic plates to 3 or more LASER beams of suitable wavelengths. Traditional halogen spotlight illumination of color holograms relying on reflection holograms’ Bragg diffraction sampling capabilities has many drawbacks. This kind of illumination, especially for a broadband hologram, results in heightened levels of chromatic dispersion and blurring of image points far from the hologram’s surface. On the other hand, by intensity mixing of selected narrow band LEDs with peak wavelengths matched to those used during recording, high quality reproduction of deep color holograms can be achieved. In this paper we will present the Holofos LED RGB and RGBW color hologram illumination devices. These devices have a wide color gamut achieved by precision, digitally controlled, RGB intensity mixing at pre-selected wavelengths. Dichroic and refractive optics combine the RGB or RGBW LEDs’ beams into quasi point-source output beam of uniform color cross section. A quantitave spectro-radiometric characterization of the Holofos devices and resolution tests results using a series of test holograms will also be presented.

In digital holographic microscopy (DHM), the long coherence length of laser light causes parasitic interferences due to multiple reflections in and by optical components in the optical path of the microscope and thus degrades the image quality. The parasitic effects are greatly reduced by using a short coherence length light. The main drawback of using a short coherence light source in an off-axis digital holographic microscope, is the reduction of the interference fringe contrast occurring in the field of view. Previously, we introduced a volume diffractive optical element (VDOE) placed in the reference arm of a DHM to correct the coherence plane tilt so as to obtain a high interference contrast throughout the field of view . Here, we experimentally quantify the spatial and temporal phase noise in the extracted phase image caused by non-homogeneities and scattering of the VDOE element itself. The results over five VDOEs show that the temporal phase noise is unchanged and a slight increase (up to 20%) is observed in the spatial phase noise. These results show that even with a low coherence source, a full field of view can be obtained with an off-axis DHM thanks to the VDOE without introducing significant additional phase noise.

Since the invention of holography in 1948, most of the attention has been focused on holographic 3 dimensional images and displays. This new 3D technology generated a lot of attention in the 70's through the 90's. The work that was being done for manipulating light other than 3D imaging and displays was not as well known. This paper discusses how holographic elements and holographic interference techniques are now being used in the Photonics industry.

A review of recent improvements and applications in color holography is provided. Color holography recording techniques in silver-halide emulsions and photopolymer materials are discussed. Both analogue Denisyuk color holograms and digitally-printed color holograms are described. The light sources used to illuminate the recorded holograms are very important to obtain ultra-realistic 3D images. In particular the new light sources based on RGB LEDs are significant improvements in displaying color holograms with improved image quality over today’s commonly used halogen lights. Color holograms of museum artifacts have been recorded with new mobile holographic equipment.

We have built a HOE-based display capable of reconstructing arbitrary images, in mid-air at fixed focal depths, that can interact with the viewer in real-time. The display system comprises the HOE, a laser projection subsystem, a Kinect motion sensor and an embedded controller. The HOE functions as a fast converging lens and is A4 page sized (20×30cm). We have written a number of simple apps for the display that allow the user to draw in mid-air or to touch icons and buttons that trigger other actions. The reconstructed holographic images are high-resolution, relatively bright and visible under ambient indoor lighting conditions.

A series of art projects that use multiplex holography as a medium to combine and spatially animate multiple photographic perspectives are presented. Through the process of image collection and compilation into holograms, several concepts are explored. The animate spatial qualities of multiplex holograms are used to express an urban gaze of moving through cites and the multiplicity of perceptual experience. A question of how we understand ourselves to be located and the complexity of this sense is also addressed. The ability to assemble multiple photographic views together into a scene is considered as a method to document the collective experience of event. How these holographic scenes are viewed is compared to the compositional activity, showing both how the holographic medium inspired the compositions and is used as a means of expression.

One of the most interesting aspects of art holography is the study of 3D holographic image. Over the centuries, artists have chased the best way to represent the third dimension as similar to reality as possible. Several steps have been given in this direction, first using perspective, then photography, and later with movies, but all of these representations of reality wouldn’t reach the complete objective. The realism of a 3D representation on a 2D support (paper, canvas, celluloid) is completely overcome by holography. In spite of the fact that the holographic plate or film is also a 2D support, the holographic image is a recording of all the information of the object contained in light. Our perception doesn’t need to translate the object as real. It is real. Though immaterial, the holographic image is real because it exists in light. The same parallax, the same shape. The representation is no more an imitation of reality but a replacement of the real object or scene. The space where it exists is a space of illusion and multiple objects can occupy the same place in the hologram, depending on the viewer's time and place. This introduces the fourth dimension in the hologram: time, as well as the apparent conflict between the presence and the absence of images, which is just possible in holography.

During the Renaissance, man placed himself in a vantage point to organise the sensorial data of the surrounding world that expressed the supremacy of his viewpoint; the man of the twentieth-first century is looking at the world as a whole from its orbit, not from inside like the Renaissance man did with perspective, but from outside, to have a entirely new view and to be able to explore and control it more firmly1. These concepts are examined and inform a series of Digital Art Holograms and Lenticular technology based on different geometries for image capture, using the HoloCam Portable Light System, with the Canon camera angled toward the floor, according different angles and different heights. Based on these geometries, some concepts of time and space are artistically explored. This artistic concept of time and space explores a method to improve the rendering of holographic space by designing forms that appear within real space.

In the course of carrying out the present work, it was stated that a parasitic surface nano-structurization is peculiar to reflective relief-phase holograms obtained on thin layers of a chalcogenide glassy semiconductor (CGS). The results of experimental researches of the effect of a relief height for reflective relief-phase holograms on the parameters of their surface parasitic nano-structurization are presented in this paper. With the use of data obtained applying atomic force microscope (AFM) Solver P-47 and software complex “Nova”, it was defined a short-wave boundary for applicability of such holograms. In addition to the conventional software complex “Nova”, aiming at reducing time necessary for determination of a short-wave boundary for relief-phase hologram applicability, there was developed a software module, which operation is based on the determination of the averaged-out over a basic area (scanning area) relief profile shape of the hologram structure, the definition of root-mean-square roughness (RMSR) values of its surface averaged-out over the same basic area, and on the subsequent computation of the boundary wavelength for the hologram applicability. The determined short-wave boundary value came to 80nm. Starting from this value, the holograms with the relief height optimal from the view of maximal diffraction efficiency meet the Marechal’s criterion σ ≤ λ/27 (σ - rootmean- square roughness parameter) and the criterion of permitted light diffusion σ ≤ λ/100. Thus, the level of light diffusion and aberration permitted for precision optical systems is ensured in a reconstructed with their use image.

We have been developing direct fringe printer that can output holographic fringe on a photosensitive material. The pixel pitch of the printer is 0.44 micro-meter and the printing speed is 3 gigapixels per hour. Although the speed is faster than that of other printing methods, more speed is desired to print over 100 gigapixels holograms. In this paper, we use high power laser to reduce the settling time that is required to eliminate vibration after a stepper motor movement. Some other improvements are also discussed.

We examined the possibility of high-density recording using shift-multiplexed holographic memory with a spherical reference beam. The use of a spherical reference beam is considered to make it possible to realize a multi-dimensional multiplex system that uses the disk track direction (x-axis), radial direction (y-axis), and disk thickness direction (z-axis); this would clearly improve the recording density when compared with the conventional angle multiplex recording. The experimental results confirm the possibility of multiple recording by 3 dimensional medium shift. Furthermore, the results indicate that a large capacity memory system of over 1 Tb/in2 can be obtained if a thick medium (about 1.5 mm) is used.

The research and development of the holographic data storage (HDS) is advanced, as one of the high-speed, mass storage systems of the next generation. Recently, along the development of the write-once system that uses photopolymer media, large capacity ROM type HDS which can replace conventional optical discs becomes important. In this study, we develop the ROM type HDS using a diffractive optical element (DOE), and verify the effectiveness of our approach. In order to design DOE, iterative Fourier transform algorithm was adopted, and DOE is fabricated with electron beam (EB) cutting and nanoimprint lithography. We optimize the phase distribution of the hologram by iterative Fourier transform algorithm known as Gerchberg–Saxton (GS) algorithm with the angular spectrum method. In the fabrication process, the phase distribution of the hologram is implicated as the concavity and convexity structure by the EB cutting and transcribed with nanoimprint lithography. At this time, the mold is formed as multiple-stage concavity and convexity. The purpose of multiple-stage concavity and convexity is to obtain high diffraction efficiency and signal-to-noise ratio (SNR). Fabricated trial model DOE is evaluated by the experiment.

We present the analysis of holographic recording in photosensitive films using albumin matrixs: gallus gallus and Callipepla cali, exposed to a λ=442nm, with ammonium dichromate, (NH₄)₂Cr₂O₇, as a photo-oxidant agent. These simultaneously were performed holographic diffraction gratings with different spatial frequencies. Getting high diffraction efficiencies of holographic gratings as a function of spatial frequency (lines/mm), known as modulo of the transfer function (MTF). We made a comparison of the experimental results between the different bird albumins.

Preparation of holographic gratings using photosensitive films pectin-H₂O-oxidizing agent exposed to a He-Cd laser, wavelength of 442nm. For the photo-oxidation, we used two agents: ammonium dichromate and iron ammonium citrate. Parallel studies performed experimental variation of angles between overlapping beams that generate the interference pattern, generating different spatial frequencies in the holographic gratings. Were prepared from pectin-water-ammonium dichromate and pectin-water-ammoniacal iron citrate. Results module of the transfer function (MTF) of the materials used, to determine the diffraction efficiencies as a function of the spatial frequency (line/mm) of each holographic gratings, which were prepared with different pectin and oxidizing agents. We made an experimental analysis of the MTF, comparing each of the films with different photosensitizers applied.

A computer generated hologram (CGH) is a hologram generated by simulating the recording process of a hologram on a computer. Various methods have been proposed for generating a hologram using CGH. However, an objective evaluation method for comparing images reconstructed by different CGH methods has not yet been established. So far, only subjective evaluation has been used to evaluate the images. The objective evaluation is necessary to standardize conditions for age of subject, vision, etc. Volume signal to noise ratio (VSNR) has been proposed for objective evaluation. VSNR is a three-dimensionally extended signal to noise ratio (SNR), that represents the difference between the spatial light distribution of reconstructed images and a real object. Although VSNR seems suitable for quality measurements in the 3D domain, measurements and comparisons of VSNR have been limited to computer simulation. In this paper, we propose a method of measuring spatial light distribution using a digital camera and measures the VSNR. Spatial light distributions are generated by taking pictures of the reconstructed images and real objects at various focal lengths. The VSNRs of various CGH calculation methods and multi-view 3D display technologies are then measured by the distributions. We compared VSNRs from different CGH methods and found that speckle noise deteriorated the VSNRs of the reconstructed images of holograms.

Head-mounted type 3-D displays are expected to be useful with Augmented Reality techniques to provide visual information. However, because these displays use the stereoscopic method to provide 3-D vision, observers tend to experience eye discomfort when viewing 3-D images due to the disparity between accommodation and convergence. Electro-holography is a rival technique that displays holograms on electrical devices such as a spatial light modulator and enables observers to view ideal 3-D images in comfort for many hours. In the current study, we applied the holography technique to an eyepiece-type display in order to solve the disparity problem. Our system can represent 3-D images at arbitrary depths and displays large reconstructed images by using a Fourier transform optical system. We also adopted the time division color method to reconstruct full-color images. In computer generated holography, holograms for each color are calculated considering with the distance between their wavelength. In this paper, we describe our calculation algorithm and report the fabrication of an eyepiecetype full color electro-holographic display for binocular vision. To confirm the effectiveness of the proposed system, the reconstructed images were evaluated both objectively and subjectively. Results of experiments show that reconstructed full-color images are located at the correct depth.

Digital holographic microscopy provides 3D quantitative phase imaging that is suitable for high resolving investigations on reflective surfaces as well as for transmissive materials. An optical configuration for a digital holographic microscope and a method for digital holographic microscopy are presented. A cube beam splitter in the optical path, with a small angle between the optical axis and its central semi-reflecting layer, both split and combine a diverging spherical wavefront emerging from a microscope objective to give off-axis digital holograms. Since the object wave and the reference wave go the same way to the CCD camera, it is called common-path digital holographic microscopy. When a plane numerical reference wavefront is used for the reconstruction of the recorded digital hologram, the phase curvature introduced by the microscope objective together with the illuminating wave to the object wave can be physically compensated. A compound digital holographic microscope (with reflection mode and transmission mode) has been build up based on this unique feature. Results from surfaces structures on silicon wafer and micro-optics on fused silica demonstrate applications of this compound digital holographic microscope for technical inspection in material science.

Holographic diffraction gratings can measure micro movements, with a system that detects each period of the moving grating. One of the important features of this device is the grating period, which determines the measurement accuracy. The period can be on the order of fractions of micron, with high reproducibility and with an error of a quarter of period. One of the qualities of this system is its robustness; the measures are invariant to noise induced by device movements and environment thermal changes.

In recent years, many types of polymers have been used in different recording holographic medium due their relatively low cost and some of them are be self-developing needing no wet processing or thermal treatment. Therefore, in this research recording materials based on Acrylamide-adhesive polymer matrix layer are prepared by gravity settling method after time drying, the layers are characterized by recording transmission holographic gratings ( LSR 445 NL 445 nm) and measuring the first order diffraction efficiency holographic parameter. This recording material has good diffraction efficiency and environmental stability.

We propose a new optical symmetric cryptographic system with simultaneous encryption and transmission of binary data and secret key by using dual phase-shifting digital holography. Dual phase-shifting digital holography contains two inner and outer interferometers which are used for encrypting data and a secret key at the same time. The technique using dual phase-shifting digital holographic interferometry is efficient because this scheme has an advantage of interference fringe data acquiring time. Binary information data is encrypted by the secret key by applying phase-shifting digital holographic method, and this secret key is also encrypted by phase-shifting digital holographic method and transmitted. Encrypted digital hologram in our method is Fourier transform hologram and is recorded on CCD with 256 gray-level quantized intensities. These encrypted digital holograms are able to be stored by computer and be transmitted over a communication network. With this encrypted digital hologram, the original binary data are decrypted by the same secret key. Simulation results show that the proposed method can be used for a cipher and security system.

Thus far, various approaches to generate the computer-generated holograms (CGHs) of 3-D objects have been suggested but, most of them have been applied to the still images, not to the video images due to their computational complexity. Recently, a method to fast compute the CGH patterns of 3-D video images has been proposed by combined use of data compression and novel look-up table (N-LUT) techniques. In this method, temporally redundant data of 3-D video images are removed with the differential pulse code modulation (DPCM) algorithm and then the CGH patterns for these compressed video images are calculated with the N-LUT method. However, as the 3-D objects move rapidly, image differences between the video frames may increase, which results in a massive growth of calculation time of the video holograms. Therefore, we propose a novel approach to significantly reduce the computation time of 3-D video holograms by employing a new concept of motion-vector of the 3-D object. In the proposed method, 3-D objects are firstly segmented from the 1st frame of the 3-D videos, and the CGH patterns for each segmented object are computed with the N-LUT algorithm. Secondly, motion vectors between each segmented object and the corresponding objects in the consecutive 3-D video frames are calculated. Thirdly, the CGH patterns for each segmented object are shifted with the calculated motion vectors. Finally, all these shifted CGH patterns are added up to generate the hologram patterns of the consecutive 3-D video frames. To confirm the feasibility of the proposed method, experiments are performed and the results are comparatively discussed with the conventional methods in terms of the number of object points and computation time.

In this paper an application of the Holographic Optical Element (HOE) which is designed by using the photopolymer is proposed. Using the HOE to replace two optic elements of the conventional HMD is possible to reduce the volume and weight. In order to implement the proposed system, we analyze the optical characteristics of the photopolymer and confirm the optimum recording condition of the HOE. The proposed system is verified experimentally.