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Photorefractive polymer composites have gained considerable attention due to their fascinating applications like 3D displays and 3D Telepresence. In this report, the performance of a novel PR polymer composite doped with graphene is studied. The addition of graphene laminates to a photorefractive composite results in up to threefold enhancement of space charge (SC) field build-up time. From our optical and electrical measurements, the faster build-up time is attributed to larger charge generation resulting from electronic interaction between graphene and the 7-DCST chromophores.

In this work, brief theoretical modeling, analysis, and novel numerical verification of a photorefractive polymer based four wave mixing (FWM) setup for defect detection has been developed. The numerical simulation helps to validate our earlier experimental results to perform defect detection in periodic amplitude and phase objects using FWM. Specifically, we develop the theory behind the detection of isolated defects, and random defects in amplitude, and phase periodic patterns. In accordance with the developed theory, the results show that this technique successfully detects the slightest defects through band-pass intensity filtering and requires minimal additional post image processing contrast enhancement. This optical defect detection technique can be applied to the detection of production line defects, e.g., scratch enhancement, defect cluster enhancement, and periodic pattern dislocation enhancement. This technique is very useful in quality control systems, production line defect inspection, and computer vision.

Photorefractive composites derived from photoconducting polymers offer the advantage of dynamically recording holograms without the need for processing of any kind. Thus, they are the material of choice for many cutting edge applications, such as updatable 3D displays and imaging through a scattering medium. This article reviews the basic properties of photorefractive polymer systems and the inherent advantages that have attracted much attention. The chemistry and physics relevant for the design of the high-performance guest−host composite are discussed and recent advances emphasized. In particular, a charge transporting polymer with high mobility and history-independent response times is highlighted, as well as polymer systems useful for holographic displays and the material considerations necessary to develop high-speed, large-sensitivity composites.

Holography is a powerful technique for providing high-resolution, realistic three-dimensional (3D) images without the need for special eyewear. A material that takes full advantage of the potential of holography, including updatability, has not existed. Here, the first updatable holographic 3D display based on a photorefractive polymer is summarized. The performance characteristics of these materials are measured, and how they relate to the development of additional display enhancements such as pulsed writing, white light viewing, and large viewing angle, are discussed.

Among the various methods to produce three-dimensional (3D) images, holography occupies a special niche. Indeed, holograms provide highly realistic 3D images with a large viewing angle capability without the need for special eyewear. Such characteristics make them valuable tools for a wide range of applications such as medical, industrial, military, and entertainment imaging. To be suitable for an updatable holographic display, a material needs to have a high diffraction efficiency, fast writing time, hours of image persistence, capability for rapid erasure, and the potential for large display area-a combination of properties that has not been realized before.

Three-dimensional holographic displays simulate natural human vision without the need for special eyewear. This makes them particularly suited to applications that require situational awareness, such as medical, industrial and military imaging. The current crop of commercial holographic 3D displays either lack image-updating capability (so are 'write-once' devices) or have poor image persistence. Tay et al. now report the development of a recording medium based on specially designed photorefractive polymers that combines a number of favourable properties. They demonstrate a holographic 3D display based on this material that can record and display new images every few minutes, has a significant size (4×4 inch), can be viewed for several hours without the need for refreshing, and can be readily erased and updated with new images. A recording medium based on specially designed photorefractive polymers that combines a number of favourable properties is used to demonstrate an updateable holographic 3-dimensional display that is capable of recording and displaying new images every few minutes, has a significant size and can be viewed for several hours without the need for refreshing, as well as being able to be erased and updated with new images when desired. Holographic three-dimensional (3D) displays1,2 provide realistic images without the need for special eyewear, making them valuable tools for applications that require situational awareness, such as medical, industrial and military imaging. Currently commercially available holographic 3D displays3 use photopolymers that lack image-updating capability, resulting in restricted use and high cost. Photorefractive polymers4,5,6,7,8,9 are dynamic holographic recording materials that allow updating of images and have a wide range of applications, including optical correlation10, imaging through scattering media11 and optical communication12,13. To be suitable for 3D displays, photorefractive polymers need to have nearly 100% diffraction efficiency, fast writing time, hours of image persistence, rapid erasure, and large area—a combination of properties that has not been shown before. Here, we report an updatable holographic 3D display based on photorefractive polymers with such properties, capable of recording and displaying new images every few minutes. This is the largest photorefractive 3D display to date (4 × 4 inches in size); it can be recorded within a few minutes, viewed for several hours without the need for refreshing, and can be completely erased and updated with new images when desired.

MI sensor is a magnetic sensor based on the Magneto Impedance (MI) effect discovered by Mori et al. in 1993[1]. A small and highly sensitive magnetic sensor (AMI 306) based on above MI effect and used as an electromagnetic compass mainly in mobile phones and smart phones has been developed and commercialized by AICHI MICRO INTELLIGENT[2]. According to theoretical analysis, the MI sensor is foreseen to show the fT/√Hz level of noise density[3], and its performance would even be equal to SQUID. MI element (AMI306) with pickup coil fabricated by a plating process is used in electromagnetic compasses. Although it shows magnetic resolution in the micro Tesla order[4], higher performance in sensitivity and noise level is required.

Low noise MI sensor (MI-CB-1DK, shows 20 pT/Hz0.5 at 10 Hz of noise density [1] based on amorphous magnetic wire has been commercialized in 2006, and has been used for detecting foreign ferrous particles in various products such as foods, medicines and industrial products produced in factories. In the case of foreign particles detection, it is required to detect foreign ferrous particles with a size of less than 1mm (especially around 0.3 mm), therefore the demand for magnetic sensor increases for tinier field detection. From such a background, we previously reported the development of low noise MI sensor by the design of amorphous magnetic wire and MI element[1]. And the research of biomagnetic measurement using this MI element has also been reported[2].

Novel acrylic acid (AA) and butyl acrylate (BA) type block polymers were synthesized by living radical polymerization and evaluated their pressure sensitive adhesive performances. AA/BA/AA type triblock copolymers have good adhesive performances and holding power even without cross-linking. According to TEM pictures, micro-domain structures were observed for these triblock copolymers. These micro-domain structures may contribute to the high holding power for adhesive samples, since it was thought that the AA block micro-domains generated the hydrogen bonding power.

The photorefractive joint transform correlator (JTC) combines two features. The first is embedded semi-adaptive optimality which weighs the correlation against clutter and noise in the input and the second is the intrinsic dynamic range compression nonlinearity which improves several metrics simultaneously without metric tradeoff. The performance of this two-beam coupling joint transform correlator scheme is evaluated against several other well-known correlation filters that have been developed during the last three decades. The result shows that the two-beam coupling joint transform scheme is a very robust correlator with respect to standard evaluation metrics for different sets of data.

Silty-to-sandy mantle and laterite sediments overlying bedrock in West Africa (Cameroon to Mali) were studied to establish their origin. Oxygen isotope values of fine quartz (1 to 10 μm in diameter) separated from the samples have a relatively narrow range (+ 15 to + 17%, vs. SMOW) and are indistinguishable from quartz separated from two Harmattan wind dust samples collected in Nigeria (+ 15.4%). However, the oxygen isotope values are distinctly different from those of quartz in samples of basement Precambrian granites (+ 10.5 to + 12.8%), gneiss (+ 13.3%o), and a Cretaceous shale (+23.2%) from the same area. The δ 18 O values of quartz from the studied soils and sediments systematically decrease with increasing particle-size. Small oxygen isotopic variations were observed for quartz up to 105 μm in size, whereas greater stable isotope variations are present in quartz fractions larger than 105 μm Oxygen isotope and particle-size frequency evidence indicate that the fine sand silt-size quartz fraction ( 105 μm) had a local origin. We conclude that the eolian fine quartz was transported by the Harmattan winds which blow from the Chad Basin to the Atlantic Ocean.

We report on photorefractive polymer composites that exhibit stable dynamic properties under continuous operation. These materials are based on a bis-triarylamine side-chain polymer matrix with a low ionization potential. The evolution of the response time for exposures up to 4 kJ/cm2 was studied and compared with that obtained in poly(n-vinylcarbazole) (PVK) based composites. In the composites, operational stability is combined with video-rate compatible dynamics, large dynamic range at moderate fields, and long shelf lifetimes.

In prior work, we exploited the nonlinearity inherent in four-wave mixing in organic photorefractive materials for adaptive filtering. In this paper, we extend our work further and demonstrate new applications which involve: dislocation, scratches and defect enhancement. With the availability of the organic photorefractive materials with large space-bandwidth product, it should open the possibility of using the adaptive filtering techniques in quality control systems.

In prior work, we demonstrate optical correlation via dynamic range compression in two-beam coupling using thin-film organic materials. In this paper, we continue the effort; characterize the performance of this correlator for variety of input. We successfully demonstrated correlation results almost free of cross- correlation and noise for extremely complicated noisy image were the signal image consist of several targets and reference image superposed of many templates.

We demonstrate image restoration and recognition via photorefractive two-beam coupling using organic photorefractive materials. Our results outperforms the simulations based on the phase-only and some optimal correlation filters.

Photorefractive composites derived from conducting polymers offer the advantage of dynamically recording holograms without the need for processing of any kind. Thus, they are the material of choice for many cutting edge applications, such as updatable three-dimensional (3D) displays and 3D telepresence. Using photorefractive polymers, 3D images or holograms can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. Absence of a large-area and dynamically updatable holographic recording medium has prevented realization of the concept. The development of a novel nonlinear optical chromophore doped photoconductive polymer composite as the recording medium for a refreshable holographic display is discussed. Further improvements in the polymer composites could bring applications in telemedicine, advertising, updatable 3D maps and entertainment.

Imaging in atmospheric turbulence and target recognition in cluttered environments have been research topics for many years. Currently, there are some well-established techniques for image restoration and recognition; however, if the atmospheric turbulence becomes a severe scattering medium and the surrounding environment is very cluttered, most conventional methods, such as inverse filtering and Wiener filtering, will be inadequate for correcting and recognizing the captured images. In this paper, we experimentally demonstrate nonlinear dynamic range compression techniques for image restoration and correlation via two-beam coupling and four wave mixing in organic photorefractive films.

In this paper, we demonstrate optical correlation via dyna mic range compression in two-beam coupling using thin-film organic materials. In contrast to the first demonstration, in which it was not possible to demonstrate correlation with complicated input, here we demonstrate correlation with extremely challenging cases involving finger prints, images in clutter, and SAR images. Our correlation results outperform many correlation results, including ones based on optimal filters. 1. INTRODUCTION In this paper, we demonstrate dynamic range compression co rrelation via a photorefractive two-beam coupling correlator (TBC) which proposed more than a decade ago . 1, 2 The correlator operates by pump ing a clean reference beam by the joint spectra of reference and signal images. The TBC has been studied extensively through computer simulations. In these studies, it was found that, for some cluttered signals, the TBC outperforms, in terms of peak-to noise ratio 2-4 , other correlators based on phase-only filters

A practical method of producing truly three-dimensional images that do not require the viewer to wear special eyewear would have many potential applications - in telemedicine, mapping and entertainment, for instance. True 3D holographic displays have so far lacked the capability of updating images with sufficient speed to convey movement. Now, a team working at the University of Arizona's College of Optical Sciences and Nitto Denko Technical Corporation in Oceanside, California, has developed a system that updates images at close to real-time. In a proof-of-concept experiment, they adapt an established technique based on holographic stereographic recording and a novel photorefractive polymeric material as the recording medium to produce a holographic display that can refresh its images every two seconds. Multicoloured and full parallax display are possible in this system - as is 3D 'telepresence', in which data describing holographic images from one location are transmitted to another location where the images are 'printed' with the quasi-real time dynamic holographic display. Holographic displays can produce truly three-dimensional (3D) images, but have so far been unable to update images fast enough. These authors have adapted a previous technique, based on holographic stereographic recording with a photorefractive polymeric material as the recording medium, to produce a quasi-real-time holographic display that can refresh its images every two seconds, and use it to demonstrate the possibility of 3D telepresence. Improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment. Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted considerable public interest since it was depicted in the original Star Wars film in 1977. However, the lack of sufficient computational power to produce realistic computer-generated holograms1 and the absence of large-area and dynamically updatable holographic recording media2 have prevented realization of the concept. Here we use a holographic stereographic technique3 and a photorefractive polymer material as the recording medium4 to demonstrate a holographic display that can refresh images every two seconds. A 50 Hz nanosecond pulsed laser is used to write the holographic pixels5. Multicoloured holographic 3D images are produced by using angular multiplexing, and the full parallax display employs spatial multiplexing. 3D telepresence is demonstrated by taking multiple images from one location and transmitting the information via Ethernet to another location where the hologram is printed with the quasi-real-time dynamic 3D display. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

In this paper, we exploit the nonlinearity inherent in four-wave mixing in organic photorefractive materials and demonstrate edge enhancement, contrast conversion, and defect enhancement in a periodic structure. With the availability of these materials, which have large space-bandwidth products, edge enhancement, contrast conversion and defect enhancement are possible.

The electron transporting molecule tris(8-hydroxyquinoline) aluminum (Alq 3 ) was introduced into a photorefractive composite in a low density to study the effects of electron traps on the performance. Compared to a control sample, Alq 3 samples exhibited higher dielectric strength, over-modulation at reduced voltage, and increased writing speed. Transient measurements indicated grating revelation via decay of a competing grating. The dynamics are consistent with a bipolar charge transport model. Overall, Alq 3 improves the sensitivity, trapping, and breakdown voltage without significant losses in absorption or phase stability.

The first updatable three-dimensional holographic display based on a photorefractive polymer device, exhibiting a fast response, long persistency, and phase stability is discussed. Material and optical setup changes for new and broader applications are outlined.

Photorefractive polymers are dynamic holographic recording materials that allow for updating of images. They have been investigated over the last decade and have a wide range of applications including optical correlation, imaging through scattering media, and optical communication. Here, we review the achievement of the first updatable holographic 3D display based on photorefractive polymers and report the fabrication of a 6 x 6 inch 2 display, the largest photorefractive 3D display to date capable of recording and displaying new images every few minutes. The holograms can be viewed for several hours without the need for refreshing, and can be completely erased and updated whenever desired.

We report the photorefractive properties of tetraphenyldiaminobiphenyl (TPD) based polymer composites that have been developed for single pulse laser operation at 532 nm. With an optimized composite, we demonstrate more than 50% diffraction efficiency using 4 mJ/cm2 single shot writing and 633 nm continuous wave (cw) beam reading. The present devices showed a 300 μs fast response time. This reveals the potential for these polymer devices in applications which require fast writing and erasure. Since the writing pulse-width is in nanosecond time scale, the recording is totally insensitive to vibrations. These devices can also be used as a stepping stone to realize all-color holography since they are sensitive to both green (532nm) and red (633nm) wavelengths. The holograms can be written with either of these two wavelengths and can be read by the same wavelength or the other wavelength with high diffraction efficiency. This demonstrates that these devices have the advantage of performing two-color holography, a step closer to a dynamic full-color holographic recording medium.

This paper presents a motion control sensor based on magneto-impedance (MI) effect. The device has 6-axis, namely 3-axis accelerometer, 3-axis magnetometer and a signal conditioning IC, in a compact package. Using this 6D (6 dimensional) motion control sensor, the attitude of an object such as a cell phone can be detected. This sensor has been embedded in Vodafone 3G mobile phone.

We propose an optically controllable device Photorefractive Connection Module (PRCM) for free-space optical interconnection between boards. The optical signal composed of a large number of spatially divided channels passes through the photorefractive material which is core of PRCM. In the photorefractive material, diffraction gratings are induced only where the control beam and the pump beam are illuminated. The signal beams in desired spatial channels can be diffracted by setting an appropriate pattern of the control beam and extracted by separating from the control beam with a beam splitter. In this study, we use organic photorefractive polymer PATPD as the photorefractive material. Diffraction efficiency of PATPD is comparable with thick inorganic crystals although the thickness of PATPD is less than 1/10 of these crystals. Thin gratings have a large advantage for PRCM because the thickness of the gratings causes large crosstalk between spatial channels. In addition, the constraint of phase matching is reduced because the phase mismatch is proportional to the thickness of the material. The decrease of the phase mismatch provides large allowance for misalignment of incident angle of beams; therefore it becomes easy to adjust incident angles. We reveal the relation of diffraction efficiency to angular difference of PATPD by analysis and experiment. Diffraction efficiency decreases by half at the difference of 0.5°, which is about ten times larger than that of thick crystals. We demonstrate that it is possible to extract the signal beams in desired channels and reconfigure the extraction pattern according to optical control by using PATPD.

Recently accelerometer attracts much attention from industries for its vast potential to the applications in the field of automobile, mobile computers, robotics and so on. Most of the newly developed accelerometers are Si based sensors with the aid of the MEMS technology. They suffer either weakness against mechanical shock or slow response to the acceleration, so some improvement is needed to apply them to the applications such as cell phones. So far the authors have developed micro MI sensor (magneto-impedance sensor) element that incorporates amorphous magnetic wire and micro-pickup coil. This paper presents a new type of accelerometer using MI element which satisfies mechanical endurance and fast response, as well as miniature size.

We have demonstrated an optical novelty filter based on the two-beam coupling effect in photorefractive polymers. The photorefractive polymer composition was optimized for response time and two-beam coupling gain by changing the ionization potential and polarizability of various components. In this study, a photorefractive polymer composition was simultaneously optimized for response time and gain, and employed as a key element in a two-beam coupling novelty filter with a high contrast ratio and a limiting frequency of 14Hz, considerably higher than any previously reported in a two-beam coupling photorefractive novelty filter.

We report on the photorefractive properties of two polymer composites that utilize a new bis-triarylamine side-chain polymer matrix. Correctly locating the frontier orbitals of the new transport manifold with respect to the HOMO levels of chromophores, allows stable continuous operation over exposure levels of more that 4 kJ/cm2 when samples are electrically biased at 57 V/μm. This operational stability is combined with video-rate compatible grating build-up times and a dynamic range that allows index modulations of 3 x 10-3 and gain coefficients on the order of 100 cm-1 at moderate fields. The thermal stability of one of the composites reported is excellent, showing no signs of phase separation even after one week at 60°C. A comparison with the stability of composites where the new matrix was replaced by PVK is also presented.

We have recently demonstrated several improvements in material properties and optical design to increase the resolution, size, brightness, and color range of updatable holograms using photorefractive materials. A compact system has been developed that is capable of producing holograms with brightness in excess of 2,500 cd/m2 using less than 20mW of CW laser power. The size of the hologram has been increased to 300mm × 150mm with a writing time of less than 8 seconds using a 50 Hz pulse laser. Optical improvements have been implemented to reduce the hogel size to less than 200 μm. We have optimized the color gamut to extend beyond the NTSC CIE color space through a combination of spatial and polarization multiplexing. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

The display of 3-D objects has always been fascinating. Recent research explores new possibilities in holographic imaging and 3-D television.

Organic photorefractive polymer composites can be made to exhibit near 100% diffraction efficiency and fast writing times, though large external slants are needed to project the applied field onto the grating vector. We show here that the use of interdigitated electrodes on a single plane provides similar performance to these standard devices and geometries but without a external slant angle. This new device's structure also greatly improves the diffraction efficiency and sensitivity compared to less slanted standard devices necessary for some real applications, such as holographic displays, optical coherence imaging, and in-plane switching.

In this paper, we exploit the nonlinearity inherent in four-wave mixing in organic photorefractive materials and demonstrate edge enhancement, contrast conversion, and defect enhancement in a periodic structure. With the availability of these materials, which have large space-bandwidth products, edge enhancement, contrast conversion and defect enhancement are possible. Some simulation results also are provided.

Researchers at the University of Arizona’s College of Optical Sciences and Nitto Denko Technical Corp. have created a rewriteable holographic display that may one day enable 3D holographic film.

Fabry–Perot interferometers (FPIs) are designed to work near and off the absorption resonance of an electro-optic (EO) polymer. The near-resonance EO activity (EO coefficient r13∼25.4pm∕V at ∼1086nm) is enhanced over that off resonance (r13∼9.0pm∕V at ∼1526nm). The full width at half maximum of the FPI transmission band is ∼16nm near resonance compared to ∼22nm off resonance. The modulation performance can, therefore, be improved with a modulation ratio increased to ∼78% near resonance (at 1064nm) from ∼19% off resonance (at 1520nm). The modulation speed is approximately megahertz and can be increased to greater than gigahertz with improved circuit design.

We present the first updateable holographic 3-D display with memory, capable of displaying a new image every few minutes. The holographic display uses a photorefractive polymer composite as recording medium with exceptional properties such as reversibility, high diffraction efficiency, large size (4×4 inches), fast recording and long hologram storage.

Individual nanosecond pulses at 532nm are applied to record gratings in photorefractive composite. At 4mJ∕cm2 illumination, maximum diffraction efficiencies of 56% have been reached with a build-up time of only 300μs (t1) demonstrating one order of magnitude faster recording compared to writing with continuous wave beams. This fast response enables applications in optical processing requiring frame rates of 100Hz or more. Due to the short duration of the writing pulses, the recording is insensitive to vibrations.