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When the scattering or absorption is large, the 3D resolution is about 100 wavelengths in holography, but the combination of scatterometry, imaging, and deep learning is a general-purpose method with a resolution of about wavelength.

Reflectivity is useful for evaluating the extinction coefficient; however, it is highly sensitive to the refractive index structure. In this study, we propose a novel, to the best of our knowledge, method for evaluating the influence of the structure on reflectivity using rigorous coupled-wave analysis (RCWA), and apply it to analyze the reflectivity of the dye rhodamine B. The reflection–absorption spectrum of the film was significantly affected by its surface and internal structure. We found that simulating the reflectivity of a film with an unknown internal structure using the coherency parameter is convenient. The RCWA facilitated simultaneous treatment of the coherent diffraction by the surface structure and incoherent reflection in the film.

We analyze the reflectivity of a film and rectangle with incoherent behavior by rigorous coupled-wave analysis. The sample was Rhodamine B on a transparent substrate, and its absorption spectrum was measured and simulated.

A novel method is proposed to measure the thickness of the indium tin oxide (ITO) film, which is less than 20 nm, using valid Fourier’s phase information of white light correlogram and curve matching algorithm. Based on the Fourier transform amplitude information, the valid phase distribution function that contains the thin transparent electrode ITO film thickness information has been successfully extracted. A curve matching algorithm based on standard deviation is employed to accurately calculate the thickness of such thin ITO films. The experimental results show that the thickness values were consistent with that determined using the stylus instruments, indicating that this method can be applied to measure the ITO film thickness ranging from 5 to 100 nm.

Nanophotonic devices, such as CMOS image sensor (CIS) pixels, are formed by stacking multiple layers of semiconductor materials. The complex refractive indices of these materials vary with the wavelength of light. Currently, industrial development of photonic devices includes a design step where light propagation is simulated using numerical methods, such as finite-difference time-domain (FDTD). Such simulations require that the refractive indices of the constituent materials be known accurately. Most commonly employed methods for computing the real and imaginary parts of the dispersive refractive indices are based either on the evaluation of the Kramers-Kronig (K-K) integral, or on the use of theoretical models of permittivity. These methods rely on the experimentally measured reflectivity or transmissivity spectra of thin films of a material to determine its refractive indices. In the first part of this paper, we describe the computation of the dispersive refractive indices of certain materials using an optimization routine based on a genetic algorithm and the coherent reflectivity and transmissivity spectra of thin-films. This approach finds the global optimum unlike earlier methods based on local optimization techniques. In the second part of the paper, we evaluated the K-K integral and used the Lorentz model of permittivity to compute the real part of the refractive index of Rhodamine B from its imaginary part. The imaginary part was determined from the transmission spectrum of a thin film of Rhodamine B. Recently, we used a similar strategy to compute the dispersive refractive index of an on-chip color filter commonly used for CIS pixel.

The data transfer rate as well as recording data density of holographic data storage systems can be improved by using a high-numerical aperture (NA) objective lens. However, a high-NA lens is likely to develop an inhomogeneous intensity profile of a reproduced holographic page data based on the polarization state of reference and signal beams during recording and readout. We analytically formulated how the polarization state of reference and signal beams during recording and readout affects signal intensity on a camera over the entire area of the page data. When Born approximation is applicable, we found that the signal amplitude of the reproduced page data can be expressed by multiplying signal amplitude calculated from scalar diffraction theory by an attenuation coefficient dependent on the polarization state. This means the intensity profile of the page data, taking polarization effect into account, can be calculated without using vector diffraction theory which requires high computational complexity. The validity of this analytical formulation was confirmed through a comparison of experiments with numerical analysis. The formulation led to a new method of increasing signal intensity of the page data area deteriorated by the polarization effect.

Reconstructing an image from the scattering pattern of particles with several wavelengths is difficult. This is because precise calculation in such cases is difficult, and because there is no proper procedure to evaluate shapes from the scattering pattern. We use rigorous coupled-wave analysis (RCWA), which we previously developed and applied to an isolated scatterer, and rotate the particle to reconstruct the image. We find that it is possible to discriminate between rectangles, triangles, and squares. The precision of length can be less than 0.2 of the wavelength, provided that the refractive index of the scatterer is known.

An accurate method for measuring the wafer surface height is required for wafer inspection systems to adjust the focus of inspection optics quickly and precisely. A method for projecting a laser spot onto the wafer surface obliquely and for detecting its image displacement using a one-dimensional position-sensitive detector is known, and a variety of methods have been proposed for improving the accuracy by compensating the measurement error due to the surface patterns. We have developed a simple and accurate method in which an image of a reticle with eight slits is projected on the wafer surface and its reflected image is detected using an image sensor. The surface height is calculated by averaging the coordinates of the images of the slits in both the two directions in the captured image. Pattern-related measurement error was reduced by applying the coordinates averaging to the multiple-slit-projection method. Accuracy of better than 0.35 μm was achieved for a patterned wafer at the reference height and ±0.1 mm from the reference height in a simple configuration.

Quasicrystal hole arrays are expected to be adopted as new focusing optical elements, owing to the characteristic self-imaging effect and the possibility of overcoming the diffraction limit. Using one such element, we achieved soft X-ray focusing. We designed a fivefold symmetric quasicrystal based on a Penrose tiling pattern consisting of 301 1.5 μm diameter holes. The light source was 10 nm synchrotron radiation. The observed diffraction pattern agreed well with the results of Fraunhofer-approximation simulations. Furthermore, the focal spot size was estimated by direct CCD imaging and found to be sufficiently small, in line with simulation results.

When the scatterer size is less than 100 wavelengths, the effect of diffraction is large. The analysis of diffraction is important for 3D shape measurement. However, in soft x rays, shapes suitable for rigorous diffraction analysis have been limited to ellipses and periodic structures. We have developed a method to expand this to any shape (isolated triangle, rectangle, etc.). Experimentally, we measured the respective widths of the cross section of a column consisting of two layers and showed that the resolution was at least a few wavelengths. For this purpose, we have also developed a fast simulation method with a small memory size.

We developed a versatile method for three-dimensional shape measurement where a specific particle can be selected on the substrate and its cross-sectional shape and size can be measured. A non-contact fast measurement is possible for the particle in the resonance domain. We applied rigorous coupled-wave analysis to the particle and calculated the diffraction patterns, comparing the patterns with the experimental results to obtain the size and shape. The shape and position of the focusing spot on the scattering particle was controlled precisely. With this method, the category of the analyzable object is extended to more shapes, such as rectangles and triangles, in addition to a conventional ellipsoid.

A hologram provides a useful model for explaining the associative memory of the brain. Recent advances in neuroscience emphasize that single neurons can store complex information and that subtle changes in neurons underlie the process of memorization. Experimental results suggest that memory has a localized character. This finding is inconsistent with the characteristics of holographic memory, because this memory has a delocalized, uniform distribution of refractive index in the recorded medium. The recently proposed columnar memory model has a discrete distribution of refractive index. In this study, we first examined the performance of columnar memory and found that it was comparable to holographic memory. Secondly, we showed that this model could explain the above-mentioned experimental results as well as associative memory.

The aim of this work is to enhance the Q value of a photonic crystal microring resonator that can be used to buffer optical signals (in a pulse train). A conventional photonic crystal microring resonator having 60° bends exhibits poor confinement of light due to the radiation losses at the bending points. Hence, we replaced conventional bent waveguides with circularly curved ones. The Q value of the resulting ring resonator is measured, and we demonstrate, as an example, an eightfold enhancement of the Q value at a wavelength of 1340 nm. Finally, we also estimate the Q value of a ring waveguide that excludes the optical coupling between the input/output waveguides, showing that the replacement of a sharply bent waveguide by a curved one increases the Q value by up to 5.2 times at a wavelength of 1340 nm.

We present an efficient means of light extraction from two-dimensional photonic crystal (2D PC) cavities with SiO 2 cladding. We propose a vertically coupled system consisting of a 2D PC cavity and a hydrogenated-amorphous-silicon (a-Si:H)-wire waveguide, which we theoretically investigate using the 3D finite-difference time-domain method. Light can be extracted with an efficiency of greater than 95% to both output ports of the a-Si:H-wire waveguide or extracted with an efficiency of greater than 90% to a single output port of the a-Si:H-wire waveguide with a reflector.

We found that the distances between isolated scatterers with similar columnar shapes could be measured by taking a single Fourier transform of their diffraction intensity. If the scatterers have different shapes, the distances between similar shapes can be selected from the distances between all the shapes. The distance from a specific scatterer can be measured with a resolution of 0.8 wavelengths and a precision of 0.01 wavelengths. This technique has the potential to be used in a novel optical memory that has a memory density as high as that of holographic memory, while can be fabricated by simple transfer molding. We used rigorous coupled-wave analysis to calculate the diffraction intensity. Some of the results were verified by nonstandard finite-difference time-domain simulations and experiments.

To realize high-precision and wide-field measurements in retardation-modulated differential interference contrast (RM-DIC) microscope, we developed a new technique to stitch plural images taken by a high-magnification objective lens with attention paid to the high edge detection ability of the RM-DIC microscope. We showed some experimental results with grating samples and made sure that the developed new method had good performance for widening the measurement field of the RM-DIC microscope.

In order to verify the authenticity of security documents, we propose the measurement of the surface distortion of the cover film of security documents. Surface shapes of films of 31 genuine documents and 29 counterfeit documents were measured by using a white light interferometer. Differences between the surface features of a genuine security document and those of a counterfeit one were studied. Roughness and peak–valley density were the two features used to characterize the measured surface shape. Only 2 out of 29 counterfeit documents could not be distinguished from the genuine ones by film distortion analysis. The likelihood ratio of this method in the authentication of genuine documents was 14.5. This implies that the proposed method is useful for authentication of genuine documents.

近年普及の著しい液晶カラーテレビをはじめとした，液晶ディスプレイに使用されているCF（カラーフィルター）の光学特性を測定し，そのコントラストを決定しているメカニズムについて考察した。カラーレジストを製造する際に，粒径の異なるジルコニアビーズを使い，分散条件を変えてモデルサンプルを作った。そしてその光学特性を測定したところ，粒径の小さいジルコニアビーズを使って分散したフォトレジストを使用したCFほど，偏光解消度が小さくなりその結果クロスニコルに配置した偏光板の間にCFを挿入した系のコントラストが向上することが示された。

While developing a three-dimensional (3-D) measurement technique for the retardation-modulated differential interference contrast (RM-DIC) microscope, we encountered a problem. The problem was that the measurement range was restricted in λ because it applies weak phase approximation. To overcome this drawback, we propose a 3-D reconstruction method with z-axis scanning. This technique needs high optical sectioning, like confocal microscopy. We investigated the characteristic of optical sectioning in a DIC microscope, then we confirmed experimentally that a DIC microscope has high optical sectioning. We also confirmed that a RM-DIC microscope has higher optical sectioning. By combining the optical sectioning of a RM-DIC microscope and z-scanning, we developed a new 3-D reconstruction method. This novel technique overcomes the observed problem as the measurement range is increased to micron order.

application/pdf, We propose a combination of ray optics and Fraunhofer multiple-slit diffraction theory for calculating the twodimensional triangular periodic grating in the resonance domain. The peak of the envelope pattern of angular distribution of diffraction efficiency is calculated by ray optics while the peak width is calculated using Fraunhofer theory. It was clarified, using rigorous coupled-wave analysis and a nonstandard-finite-difference timedomain method, that the envelope pattern of the diffraction of the grating could be calculated easily and understood intuitively for the design of displays and lighting.

A polarization-sensitive swept-source optical coherence tomography system (central wavelength: 1,310 nm; A-line rate: 20 kHz) was developed to evaluate the three-dimensional structure of the anterior eye segment with the phase retardation associated with the anterior segment birefringence of the eyes. Evaluation of normal eyes and an eye with necrotizing scleritis was performed. In the sclera of the normal eyes, a striking polarization change was observed in the cumulative phase retardation images and the boundary of the sclera could be readily detected. In the eye with necrotizing scleritis, phase retardation at the sclera was low in an extensive area; this implied diffuse destruction of the collagen tissue in the sclera had occurred. Polarization-sensitive optical coherence tomography is useful as a contrast engine of the anterior eye segment and for the evaluation of pathological change in the sclera. [Ophthalmic Surg Lasers Imaging 2009;40:607-610.]

A two-dimensional photonic crystal directional coupler is a flexible optical component that can easily change optical properties such as operating frequency, wavenumber, and group velocity. We investigate the changes in the photonic bands with geometrical modulations such as radii and positions of air holes by the finite-difference time-domain method. Following the calculations, we classified the modulations by their effects on the photonic band: producing a flat band and shifting the normalized frequency of propagation modes of the coupled waveguide. We also discuss the physical implications of the relationship between the modulations and their effects on photonic bands. Finally, we applied this knowledge to the adjustment of the normalized frequency of a flat band, and then, we show that the normalized frequency of a flat band 0.291 can be decreased to 0.286. This demonstration indicates that the findings of this study can be used to obtain the desired optical properties of a directional coupler.

A two-dimensional photonic crystal waveguide with a novel geometry is introduced. The center line of this waveguide is bent along a free-curve such that the direction of the propagating light can be changed without scattering or reflection losses. The design method is described for a triangular lattice, its optical properties such as transmission spectrum and dispersion relation are calculated, and actual devices are then fabricated and demonstrated that they worked as optical waveguides.

application/pdf, Focus analysis techniques from computer vision are applied to digital holography to determine the depth (range) of multiple objects and their surfaces from a single hologram capture. With this method the depths of objects can be determined from a single hologram capture without the need for manual focusing and without prior information on object location. Variance and the Laplacian of Gaussian are analyzed as focus measures, and techniques are proposed for focus plane determination from the focus measure curves. The algorithm is described in detail and demonstrated through simulation and optical experiment.

While considering measurements of grating-type samples with the retardation-modulated differential interference contrast (RM-DIC) microscope, we found a problem of phase objects. The problem is that smaller measured values than the actual phase distribution are obtained when phase objects are beyond the weak phase approximation range. We analyze the image characteristics of phase objects and show that the problem is caused by the effect of an image component which is proportional to the square of the phase distribution. To overcome this disadvantage, we propose a new analysis method named self phase-correction (SPC). The SPC method corrects the phase distribution of the first order approximation under the weak phase condition and obtains the actual phase distribution of an object’s phase beyond the weak phase approximation range. We propose a two-image SPC method and a three-image SPC method for the RM-DIC microscope, and examine the suitability of these methods. We confirm that the three-image SPC method effectively overcomes the problem, and that the measurement range of the RM-DIC microscope can thus be extended to a half-wavelength phase difference.

The orientational stabilities of three azobenzene-containing materials were compared. The azobenzene was aligned by linearly or elliptically polarized light. The polarization state was recorded by inducing optical anisotropy using excitation light. The optical anisotropy was evaluated by measuring Stokes parameters of probe light. The stable condition for polarization recording was investigated. It was verified that cooperative molecular reorientation by several azobenzene side chains in azobenzene copolymer is effective for stable optical data storage by polarization recording.

Optical performances of a unique photoinduced chiral material were investigated. The material employed in our study is an azobenzene-based copolymer (PCDY50) that exhibits a very large photoinduced birefringence and a superior stability of photoinduced molecular orientation state. The photoinduced chirality of the PCDY50 thin film was analyzed in detail by elliptical analysis on the basis of either circular or linear polarization. The validity of the processes is demonstrated by comparing experimental results and calculations. Consequently, the formulation based on circular polarization is appropriate for analyzing the relationship between the polarization state of incident and transmitting beams accurately. Furthermore, photoaddressable polarization-altering functions, for example, as an optical rotator, an ellipticity modificator and a circular polarization generator were examined by applying the invariant ellipticity (or azimuth) state condition to an 800-nm-thick PCDY50 film. Some possible applications of the photoinduced chiral thin film are also suggested.

We investigated thermal-lensing effects in a side-pumped 1.3-μm Nd:YVO4 slab laser amplifier having a bounce geometry. The thermal-lens power during 1.3 μm laser action was 1.3-times larger than that without laser action. Excited-state absorption is the main cause for increased heat loading during laser operation. The heat-loading formula in end-pumped 1.3-μm vanadate lasers having low Nd doping can be extended to account for heat generation in diode-side-pumped vanadate bounce lasers having high Nd doping. Key words: Diode-pumped lasers, Thermal lensing, Interferometery PACS: 42.55.Xi, 65.40.-b

A novel method of optical data storage was proposed using the rotation of polarization. The optical data was recorded as a chiral structure formed in a film made of an azobenzene copolymer using elliptically polarized light irradiation. The elliptically polarized light of a reading light was digitized into two states, "0" and "1". The initial state is defined as "0", while state "1" is observed by an optical rotation of the reading light, which is achieved by the photoinduced chiral structure formation. The recording characteristics were investigated by varying the intensity of the recording light and the recording time. Since the chiral structure was erased by circularly polarized light, state "1" could be reversed to state "0". The possibility of using our proposed method for achieving next-generation rewritable, multilevel, and parallel optical data storage was discussed.

Line-field spectral domain optical coherence tomography (LF-SDOCT) has been developed for very high-speed three-dimensional (3D) retinal imaging. By this technique, the A-line rate significantly improved to 823,200 A-lines/s for single frame imaging and 51,500 A-lines/s for continues frame imaging. The frame rate at continues frame imaging is 201 fps. This 3D acquisition speed is more than two fold higher acquisition speed than the standard flying spot SD-OCT. In this paper, the integration time of the camera was optimized for the in vivo retinal measurement and the degradation of the lateral resolution due to the ocular aberrations was suppressed by introducing the pupil stop. Owing to an optimal integration time, the motion artifact can be significantly suppressed. Also a pupil stop was employed in order to enhance the contrast of the OCT image for the effect of ocular aberrations. The in vivo 3D retinal imaging with 256 cross-sectional images (256 A-lines/image) was successfully performed in 1.3 seconds, corresponding to 0.8 volume/s. The maximum on-axis system sensitivity was measured to be 89.4 dB at a depth of 112 μm with an axial resolution of 7.4 μm in tissue. It is shown that LF-SDOCT might have a sensitivity advantage in comparison to the flying spot SD-OCT in the ultra high-speed acquisition mode., This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?id=137894. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

We propose a non-iterative deconvolution method that can improve the out-of-focus lateral resolution in line-field spectral-domain optical coherence tomography. By using an inverse filter designed from the point spread function of the system, the out-of-focus lateral resolution can be enhanced to a level comparable with the in-focus resolution over the entire axial measurement range. The resolution before and after this deconvolution has been verified experimentally. Furthermore, the method has been applied to the measurement of an ex vivo porcine eye chamber, which has demonstrated that the method was satisfactorily applicable to biomedical applications.

Development of permeable pavement, which has durability and sufficient permeability even under the condition of heavy traffic and/or soil sub-grade, has been necessary in recent years to prevent river flood in urban region. Laboratory tests, full-scale accelerated loading test and 3 years' test pavements constructed all over the Japan have clarified: 1) Permeable pavement on sand layer has the same durability as the ordinary pavement. 2) When the pavement need to be constructed on a soil layer, drainage from sub base-course could be an effective countermeasure to improve its durability. 3) Its permeability has not been deteriorated after 2-3 years service. 4) Permeable pavement could be effective for preventing river flood by reducing and delaying run-off.

The physical model of photoinduced mass transport, which was previously proposed, was improved. A novel numerical method was developed to analyze electromagnetic field distribution and energy transformation in more detail. The electromagnetic field was calculated using a modified cubic interpolated propagation/constrained interpolation profile (CIP) method. The mass transport was calculated using a particle method proposed previously. The photoinduced surface relief of an azobenzene polymer film formed by optical near-field exposure was simulated using a proposed physical model and a numerical method. The numerical results were compared with experimental results. The surface profile and energy dependence of thne photoinduced surface relief formation obtained numerically were coincided with the experimetal results.

Based on weak phase approximation and the partial coherence theory, we analyze the image characteristics of a phase object using a microscope. We show that the image of the phase object is formed by the interplay between the phase distribution and the defocus. Using this theory, we also show the image characteristics of a differential interference contrast (DIC) microscope. We develop a method for extracting the phase component from the DIC image using two images with different retardation to reconstruct the phase distribution of the object. We call our new microscope a “retardation-modulated DIC (RM-DIC) microscope”. We describe the RM-DIC microscope and confirm our method using grating samples with depths of 20 and 50 nm. To measure the three-dimensional (3D) figures of the microstructures on the object using a DIC microscope we need to extract the phase component from the DIC image and to deconvolute the phase component by means of the modulation transfer function (MTF) of the DIC microscope. We conclude that our RM-DIC microscope can take quantitative measurements of the phase distribution, making it a very useful tool for 3D measurement of an object’s microstructures.

We have achieved high average power Raman output from a compact, diode-pumped, self-stimulating Nd 3+ :KGd(WO 4 ) 2 Raman laser. Maximum Raman output power of 0.8 W was achieved at a pulse repetition frequency (PRF) of 2 kHz. The optical efficiency from diode to Raman laser was 14%. By generating extra-cavity second harmonics using a LiB 3 O 5 crystal, it was possible to produce 0.2 W yellow output. The laser system was simulated numerically using rate equations and the results obtained were in good agreement with the experimental results.

Photoinduced chirality in azobenzenes has been investigated. Even in low-molecular weight azobenzenes, photoinduced optical rotation could be observed and the characteristics were similar to that of ever reported in azobenzene side-chain-type polymer. Any relationship between molecular chirality and photoinduced chirality could not be observed in low-molecular weight azobenzenes. Further, very large optical rotation of 41 deg./μm could be observed in an azobenzene copolymer containing large birefringent unit. Dependence of optical rotation on intensity, wavelength and ellipticity of excitation beam were examined. The phenomenon was discussed based on the assumption that photoinduced helical structure was formed by elliptically polarized beam irradiation.

A set of fully automated algorithms that is specialized for analyzing a three-dimensional optical coherence tomography (OCT) volume of human skin is reported. The algorithm set first determines the skin surface of the OCT volume, and a depth-oriented algorithm provides the mean epidermal thickness, distribution map of the epidermis, and a segmented volume of the epidermis. Subsequently, an en face shadowgram is produced by an algorithm to visualize the infundibula in the skin with high contrast. The population and occupation ratio of the infundibula are provided by a histogram-based thresholding algorithm and a distance mapping algorithm. En face OCT slices at constant depths from the sample surface are extracted, and the histogram-based thresholding algorithm is again applied to these slices, yielding a three-dimensional segmented volume of the infundibula. The dermal attenuation coefficient is also calculated from the OCT volume in order to evaluate the skin texture. The algorithm set examines swept-source OCT volumes of the skins of several volunteers, and the results show the high stability, portability and reproducibility of the algorithm., This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=oe-14-5-1862. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

A numerical deconvolution method to cancel lateral defocus in Fourier domain optical coherence tomography (FD-OCT) is presented. This method uses a depth-dependent lateral point spread function and some approximations to design a deconvolution filter for the cancellation of lateral defocus. Improved lateral resolutions are theoretically estimated; consequently, the effect of lateral superresolution in this method is derived. The superresolution is experimentally confirmed by a razor blade test, and an intuitive physical interpretation of this effect is presented. The razor blade test also confirms that this method enhances the signal-to-noise ratio of OCT. This method is applied to OCT images of medical samples, in vivo human anterior eye segments, and exhibits its potential to cancel the defocusing of practical OCT images. The validity and restrictions involved in each approximation employed to design the deconvolution filter are discussed. A chromatic and a two-dimensional extensions of this method are also described., This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=oe-14-3-1006. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

A novel model for photoinduced mass transport was proposed. The equation of motion describing the photoinduced mass transport was obtained by introducing inhomogeneous viscosity and incompressibility to Cauchy's equation of motion, which is a master equation of the phenomenon. The force that acts on the dipole that is induced in azobenzene polymer by the electromagnetic field and surface tension force were considered to be the driving forces for photoinduced mass transport. A newly developed electromagnetic-induced particle transport method based on moving particle analysis was used to calculate the equation of motion and the electromagnetic field numerically. The surface relief grating was formed by illuminating two-beam interference and the surface relief shape was investigated using the original calculation method. The inhomogenous viscosity that explains this phenomenon was investigated by considering the SRG erasure process in detail.

A photoresponsive amorphous copolymer that consists of cyanoazobenzene and a large birefringent moiety with extended π-conjugation was recently designed and synthesized. It has been confirmed that this copolymer exhibits a very large optical rotation of 41°/µm under the optimized excitation conditions practically determined within our optical setup, i.e., 457.9 nm, 30 mW and ellipticity=-0.5. The large rotation angle observed could be attributed to the increment of the order parameter of the polymer side chains promoted by the introduction of the extended π-conjugated moiety. Even more, the dependence of optical rotation on beam power, wavelength and ellipticity of the excitation beam has been examined. The phenomenon of photoinduced chirality in an azobenzene amorphous copolymer is discussed and analyzed on the basis of general ellipsometry by solving the transformation matrix of the sample.

High speed complex full-range Fourier domain optical coherence tomography (FD-OCT) is demonstrated. This FD-OCT requires only a single A-scan for each single transversal position for full-range Fourier domain optical coherence tomography. The Fourier transform method is applied along the direction of the B-scan to reconstruct complex spectra, and the complex spectra compose a full-range OCT image.

(SS-OCT) system, which uses a ready-to-ship scanning light source, is demonstrated. The light source has a center wavelength of 1.31 μm, -3 dB wavelength range of 110 nm, scanning rate of 20 KHz, and high linearity in frequency scanning. This paper presents a simple calibration method using a fringe analysis technique for spectral rescaling. This SS-OCT system is capable of realtime display of two-dimensional OCT and can obtain three-dimensional OCT with a measurement time of 2 s. In vivo human anterior eye segments are investigated two- and three-dimensionally. The system sensitivity is experimentally determined to be 112 dB. The three-dimensional OCT volumes reveal the structures of the anterior eye segments, which are difficult to observe in two-dimensional OCT images. A two dimensional tomographic movie shows a dynamic motion of a human iris., This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-13-26-10652. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.

We report fabrication of ultra-fast optical switches operated at a wavelength of 1064 nm using spin-coated one-dimensional polymeric photonic crystals doped with nonlinear-optical dyes. The optical switches are controlled either by an applied electric-field voltage or by a pump light by use of two different optical-configurations. The response time of the electro-optic switch and the all-optical switch are limited by the applied voltage and the laser used, respectively. The polymeric photonic crystals can be easily fabricated with low cost.

We propose a direct fabrication of light diffusers using azobenzene polymer films. Holographic recordings of surface relief diffusers are formed on the polymer film by exposure to an Nd:YAG laser (532 nm) through source diffusion materials. No post-treatment is needed, and it can be erased by heating or irradiating uniform laser beam. Diffusion pattern can be controlled by the polarization of the laser. Transmittance of over 88% is obtained at the wavelength of 633 nm.

Surface relief holograms are fabricated by irradiation of laser interference patterns on an azobenzene polymer film. The hologram needs no post-treatment, and can be erased by heating the films to above its glass transition temperature. Rewritable Fresnel holograms are fabricated on azo-polymer film. Replication of the surface relief hologram is also demonstrated. An application for business cards is considered.