This PDF file contains the front matter associated with SPIE Proceedings Volume 7851, including the Title Page, Copyright Information, Table of Contents, Introduction, and the Conference Committee listing.

The volume holographic correlator can be used in the fast scene matching. However, the traditional volume holographic recognition method is unable to implement rotation-invariant scene matching. In the multi-sample parallel estimation method, the intensity of the multiple correlation spots can also reflect the information of the rotation angle between the target image and the template image. Thus it can be used to derive the rotation angle in the post processing and the rotation-invariant scene matching can be realized. The function between the rotation angle and the intensity value of the correlation spots is presented. The experimental results show the validity of the proposed method. The rotation angle of the target image can be precisely derived and the maximum rotation angle is as big as five degree. This method is able to save much capacity of the volume holographic correlator, enlarge the scene matching scope and improve the recognition accuracy.

The demand on sensors for detecting chemical and biological agents is greater than ever before, including medical, environmental, food safety, military, and security applications. At present, most detection or sensing techniques tend to be either non-molecular specific, bulky, expensive, relatively inaccurate, or unable to provide real time data. Clearly, alternative sensing technologies are urgently needed. Recently, we have been working to develop a compact fiber optic surface enhanced Raman scattering (SERS) sensor system that integrates various novel ideas to achieve compactness, high sensitivity and consistency, molecular specificity, and automatic preliminary identification capabilities. The unique sensor architecture is expected to bring SERS sensors to practical applications due to a combination of 1) novel SERS substrates that provide the high sensitivity and consistency, molecular specificity, and applicability to a wide range of compounds; 2) a unique hollow core optical fiber probe with double SERS substrate structure that provides the compactness, reliability, low cost, and ease of sampling; and 3) an innovative matched spectral filter set that provides automatic preliminary molecule identification. In this paper, we will review the principle of operation and some of the important milestones of fiber SERS sensor development with emphasis on our recent work to integrate photonic crystal fiber SERS probes with a portable Raman spectrometer and to demonstrate a matched spectral filter for molecule identification.

With the rapid development of fiber optic sensing technology, more and more related monitoring programs begin to play an important role in oil and gas exploration. In the past, down-hole monitoring of temperature and pressure was dependent on pump partner, electronic pressure gauge and the capillary pressure gauge. However, such devices show many disadvantages in stability, reliability, accuracy and so on. In the interest of special anti-corrosion, seals, high temperature, high pressure treatment, and long life, the fiber optic sensor is critically investigated and a new design approach of fiber temperature and pressure sensor based on Fiber Bragg Gratings and Fabry-Perot Cavity is presented, respectively. The temperature and pressure resolution of this sensor can be as high as 0.3°C and 3psi. Meanwhile, the sensor can work under the condition from 0 to 15000psi and from -25 to 300 °C. This paper describes the technical principles, characteristics and field application of the sensor in detail.

Accurate phase retrieval from single fringe pattern is significant for dynamic phase measurement. Although it brings issues of speckle noise and severe non-sinusoidal waveform, the interference fringe pattern by coherent light is still often used for profile measurement, especially for measuring target with low reflective surface. Both simulation and experiment are carried out to study performance of two-dimensional Fourier transform, windowed Fourier transform(including windowed Fourier filtering and windowed Fourier ridges), and wavelet transform methods. The influence of the speckle noise and non-sinusoidal waveform to those phase retrieval methods is compared and discussed.

Random phase mask has been widely used for increasing security of holographic image encryption. This works study effect of random phase mask on quality of decrypted images through computer simulations. The results show that the image quality depends of the position of the phase mask with respect to the input image.

A novel single-channel color image encryption technique based on joint fractional Fourier transform correlator(JFRTC) and phase retrieval algorithm (PRA) is proposed. The target color image is decomposed into three red, green, blue (RGB) components. A joint image is formed and encoded into two random phase masks (RPM) iteratively. The security of the system is enhanced because of the fractional order as a new added key. The system and the operation procedure are simplified. Simulation experiments show that the algorithm converges rapidly and has great design flexibility. The decryption can be realized by digital or optical methods.

Data security techniques based on optical theories and methods have been proposed and widely developed in recent years. Compared with conventional mathematical encryption methods optical security system provides higher processing speed, more information volume, more encryption free-degree as well as its multi-dimension and parallel processing abilities. In this paper we proposed a novel architecture for optical image encryption with polarization-selective diffractive optical element (PDOE) based on interference theory. A target image is firstly encoded into two phase-only distributions and then these phase distributions are encrypted into the etched surface-relief pattern of a single PDOE mask. In the process of optical image decryption, when the working wavelength and the system configuration are correct, the PDOE mask with the encoded information for the target image can generate two desired polarized wavefronts by modulating the incident light beam. These two wavefronts interfere and then generate the decrypted image. The encoding algorithm to generate the phase-only distributions is simple and it does not need iterative process. The optical realization for image decryption also has the advantages of easier installation and collimation since all the optical elements are in a same optical axis. The employment of the PDOE mask in this optical security system will highly increase the information security and still maintain the parameter sensitivity in an acceptable region. Numerical simulation is performed to demonstrate the validity of this new proposed method.

In this paper, we introduced a concept of cascaded phase-truncated Fourier transforms (CPTFTs), which is a nonlinear iterative operator. Meanwhile, an optical/digital hybrid system was presented to implement the operator of CPTFTs. Thereafter, by adopting CPTFTs as main processing unit, we have done some research on optical one-way cryptosystem: an optical Hash function (O-Hash) and a keyed optical Hash function (K-O-Hash) were put forward respectively, which can be applied to message integrity check and authentication. Both of the O-Hash and K-O-Hash can transform an arbitrary-length pre-encoded message (without or with a secret key) into a fixed-length output by means of taking a two-step one-way encryption process. Finally, a set of numerical experiments were carried out to evaluate the performance of avalanche effect and collision resistance of the O-Hash and K-O-Hash constructed with our approach.

An optical recording technique, called retardagraphy, has been proposed, in which, retardance distribution of a birefringent object can be recorded on a polarization-sensitive medium made of an azobenzene copolymer. The phase difference distribution between two orthogonal polarization components of the wavefront to be recorded can be directly recorded. The multi-valued phase pattern recorded can be reconstructed by measuring retardation between two polarization components by an imaging polarimetry technique. In this paper, the optical recording and reconstructing methods in retardagraphy are presented. Its application to optical mass data storage is discussed.

In this work, to investigate the feasibility of plasmonics for data storage, we studied several aspects of the plasmoincs in confining and enhancing the light field in subwavelength metallic structures. Starting from the brief review on the plasmonic resonance in simple metallic nano-structures such as metallic ellipsoid and ellipsoidal metallic void, we extended our interest to the metallic apertures as a near-field transducer for data storage devices. Based on the several numerical calculations, simple and intuitive features in designing considerations such as resonance mechanisms, figureof- merits, topological considerations in metallic apertures are discussed.

In this paper, the position selectivity of holograms recorded with orthogonal-phase coded reference beams is investigated by numerical simulation and preliminary experiments. The results of numerical simulation show that with a phase-coded reference beam, the brightness of the reconstructed image is sensitive to the relative shift between the hologram and the phase-coding pattern of the reference beam. The position selectivity is not worse than 40μm in both lateral directions. The results of preliminary experiments also show that the position selectivity is even better. According to both the numerical simulation and the experiments, it is clear that with orthogonal phase-coded reference beams, the position selectivity can be satisfying for holographic storage. This suggests that a new hybrid multiplexing method, which incorporates orthogonal phase-coding multiplexing into shift-multiplexing, could be suitable for high-density and high-fidelity holographic storage.

In this paper, we suggest a simple method of making specified random-phase shifters which are used for speckle-shift multiplexing in photopolymers. Compared with other kinds of diffusers, they are easier to be made and designed to control the average speckle size so as to accommodate the requirement for high storage density. The experimental scheme and the theoretical calculation of the desired speckle size are given. Then the difference between the experimentally measured and theoretically calculated speckle size is discussed. Finally the unfavorable factors which influence the performances of shift-multiplexing using this scheme are discussed, and the feasible solutions to those problems are given.

CBHD (China Blue High Definition Disc) is a high-definition optical disc standard with Chinese independent intellectual property. Compared with DVD optical pick-up, CBHD optical pick-up, key component of CBHD player, has significant improvement in the channel bit rate and certain reduction in acceptable tolerance range for disk tilt, etc. This paper specifies the servo control system construction for the CBHD radial tracing and axial tracking. This servo control system should ensure the optical beam of OPU focusing on the Disc plane and following the track of CBHD channel accurately. According to the expected radial/axial maximum acceleration and the limitation of emax, an open-loop transfer function specifying the servo system for axial and radial tracking is introduced. The corresponding servo control algorithm including IIR filter based on the above-mentioned transfer function is theoretically analyzed and numerically simulated by MATLAB. Because optical pick-ups are different in dynamic properties and its digital circuit exist quantization error, time delay nonlinearity, etc, the tuning of IIR parameters is laborious and time-consuming. Thus a experimental platform for CBHD optical pick-up servo system are designed in this paper, and an user-friendly interface for IIR parameters adjustment is given. Experimental results showed that this control system has good servo characteristics in time-domain and frequency-domain.

A novel single-beam holographic tomography (SHOT) based technique is used for the recording and reconstruction of 3D shapes of water droplets, leading to quantification of the radii of curvatures along the surface, droplet separation, and number density.

Up to now, a variety of methods have been developed for the single-shot THz detection, which include spectral encoding technique [2-3], optical streak camera [4], non-collinear geometry spatial encoding [5], non-collinear cross correlation technique [6], retrieval algorithm based on in-line spectral interferometry [7], two-dimensional electro-optic imaging with dual echelons [8], tilted front collinear geometry [9], etc. For a single-shot characterization of THz pulse, all of the schemes mentioned above can be, however, only employed to measure the electric field of a single-shot THz either in its spatial or temporal domain, respectively, in real time. In this paper, we describe a method for a single-shot recording of the full spatiotemporal electric field, E(x, y, t), of freely propagating terahertz pulse based on the electro-optic (E-O) sampling technique and the pulsed digital holographic approach. From a series of sub-holograms recorded digitally, the complete THz electric field E(x, y, t) can be recovered by the following digital reconstruction algorithm. The spatial and temporal resolutions are limited by the wavelength of terahertz pulse and the probe pulse duration, respectively. Our new method will open a possibility of a full characterization of the three-dimensional THz field E(x, y, t) in a single-shot mode.

Nondiffracting beams are of interest for optical potential applications owing to their properties of smaller central spot, longer propagation distance and so on. A phase-holograms-based method of generation of nondiffracting beams array with arbitrary order is proposed in this paper. If a phase hologram is displayed on a phase-only spatial light modulator (SLM), when a collimated monochromatic plane wave illuminates it, an annulus with high concentration of energy is obtained in the Fourier plane. Then through the Fourier transform again, a nondiffracting beam will be generated. It is able to generate arbitrary order nondiffracting beams with high diffractive efficiency. More significantly, if a phasehologram- array that possesses the same eigenvalue is utilized, a unique bright annulus will be generated in the Fourier plane because of the shift-invariance of Fourier transform and the consistency of phase hologram design. Then through the Fourier transform again, a nondiffracting beams array will be generated. Furthermore, the location and the order of each individual nondiffracting beam can be customized according requirement. Experiment results are in good agreement with the numerical simulation and the theoretical analysis.

In the paraelectric phase photorefractive crystal, the quadratic electro-optic effect can result in Bragg gratings in the volume of the crystal. The reconstruction process and the diffractive properties of the grating can be governed by the externally applied electric field. The measurement of the diffraction efficiency as a function of the applied electric field during recording is described. Dependence of electrically controlled Bragg grating in paraelectric phase KLTN: Cu crystals on readout illumination beam polarization were experimentally investigated. The results of experiments show that the diffraction efficiency of electric-controlled volume grating can also be controlled by the polarization of readout light. All these results would offer an possibility for a photorefractive optical switch by adjusting the polarization of the readout beam to control the diffraction efficiency.

We propose a novel method of skin image reconstruction based on color generation using Monte Carlo simulation of spectral reflectance in the nine-layered skin tissue model. The RGB image and spectral reflectance of human skin are obtained by RGB camera and spectrophotometer, respectively. The skin image is separated into the color component and texture component. The measured spectral reflectance is used to evaluate scattering and absorption coefficients in each of the nine layers which are necessary for Monte Carlo simulation. Various skin colors are generated by Monte Carlo simulation of spectral reflectance in given conditions for the nine-layered skin tissue model. The new color component is synthesized to the original texture component to reconstruct the skin image. The method is promising for applications in the fields of dermatology and cosmetics.

Lasers used in dermatological treatments are presented. Commercially available semiconductor lasers (laser diodes) are also presented for comparison. Potential applications of semiconductor lasers to noninvasive information processing or diagnosis as well as medical treatment are discussed. In addition, the current application of LEDs to dermatology is also included in the paper.

A new method which makes use of the variable accelerated motion of servo motor is presented to fabricate the triangular fiber Bragg grating. Considering the exponential relationship between the changes of grating refractive index and the exposure of UV laser, this method only requires one exposure, the variable accelerated motion of servo motor is controlled by computer program to control the increment of UV laser exposure and the linear change of grating refractive index on the fiber axial, then the edge of triangular fiber Bragg grating can be gained. The experiment result shows that the edge of triangular fiber Bragg grating has a good linearity, the bandwidth is 1.6nm, the linear bandwidth which can be used is 1nm, and the maximum reflectivity is 90%. As a fiber Bragg grating sensor demodulation device, triangular fiber Bragg grating will be more widely used in sensing fields.

In this letter, a tunable chromatic dispersion compensating in 40Gbit/s system based on enhanced thermal chirping fiber Bragg grating is demonstrated. The dynamic dispersion is provided by a tunable dispersion compensator based on enhanced thermal chirping fiber Bragg grating, which can change the group velocity delay (GVD) without changing the center wavelength or change the center wavelength with a fixed group velocity delay (GVD).

We propose faced folded rods (FFR) as nano-antenna for light emissions. This FFR structure, which is composed of two folded gold rods, shows two different field enhancement modes depending on the polarization direction of feeding light. Under the incidence of x-polarized light, double hot spots are observed at gaps due to capacitive coupling between rods. Meanwhile, when y-polarized light is applied to this geometry, a single hot spot is achieved at the center of the structure which is due to the superposition of half-wavelength dipole resonance occurring at each folded rod. Strong resonance of several vertices, which is predicted to be 100 of electric field enhancement factor in FFRs, can be achieved for sensitive bio-molecular detection. Thus, we can manipulate the number and position of desired hot spots by way of controlling the polarization state of light. Since we can obtain up to four different hot spot areas in nano-meter scale, multiplexed biosensing can be possible using FFRs as the nano-antenna. To understand the physical mechanism behind the pair type of folded rods, a single folded rod is first simulated as a basic elementary structure and compared with the pair structure. Then, this FFR structure is fabricated with an electron beam evaporator and the focused ion beam lithography. The scattered light intensity is captured by a CCD camera and compared with the simulation data.

The diffraction far-field of planar waveguide is investigated and then rationality of the Gaussian approximation for it is clarified based on the characteristic of its beam propagation factor. A new definition for divergence half-angle is presented according to the maximal matching efficiency method, furthermore, relationship between the maximal matching efficiency divergence half-angle and normalized frequency is given.

Optoelectronic technology played a pivotal role in the unprecedented information revolution in the past two decades. One of the remaining grand challenges is the ability to store an optical signal in optical format. So slowing down the velocity of light have recently attracted substantial interest. In various mechanisms of slow light generation, semiconductor optical amplifier (SOA) attracts much attention because it offers the advantage of compactness, room temperature operation, electric-optical controllable and easy integration with existing optical communication systems. In this paper, slow light generation in SOA using four wave mixing (FWM) effect is analyzed. The dynamic changes of the signal light time delay with the outside controllable parameters, such as the injection current into SOA, the pump light power, the detuning frequency between pump light and signal light, are numerically solved on the basis of the theory of refractive modulation-index and the sub-sections model of SOA. This method has the advantage of accurate simulated results and providing the explicit relationships between the controllable parameters with the signal light time delay for the practical experiment.

Based on the non-paraxial vectorial moment theory of light beam propagation and waveguide mode theory, the beam parameters of single-mode fiber including mode-field radius, divergence half-angle and beam propagation factor are analyzed and calculated. Especially, the results of beam propagation factor show that if both the core and cladding layer fields are considered, M²>1 is always obtained and neglect of the cladding layer field will lead to M²<1. These conclusions may be useful for further research on beam quality of fiber laser beam.

In this letter, a novel simultaneous demultiplexing and clock recovery unit based on EAMs and clock recovery module is presented and experimentally demonstrated for a high speed OTDM system. The 10GHz clock signal with low jitter is extracted from 80Gbit/s and 160Gbit/s OTDM signal, and every channel of the OTDM signal is successfully demultiplexed using this unit. The power penalty is lower than 3dB at BER of 10^-9.

The crosstalk reduction of differential readout technology for Super-Resolution Near-field Structure (Super- RENS) disc system is analyzed. We calculate the crosstalk for both differential readout technology and normal readout technology by using scalar diffraction theory. Numerical analyses indicate that the differential readout technique is effective as a mean of crosstalk reduction. Further analyses demonstrate the effects of different Gaussian-weighted beams, defocus and track error on cross-talk ratio for both readout technologies. Simulations show that the wide incident beam is preferable to gain low crosstalk. By comparing the two kinds of readout technologies, we also find that the differential readout technology always obtains higher quality signal.

The fixing phase of the two-center holographic recording is not consistent with the mono-exponential formula, and the charge-transfer mechanism of the fixing phase is studied theoretically. The electron gratings of the shallower traps center have a great influence on the fixed space-charge-field, the stronger electrons grating of the shallower traps center would enhance the saturation space-charge-field of the deeper traps center in the fixing phase. The effects of the Fe concentration, Cu concentration and the oxidization-reduction state of the crystals on the fixed space-charge-field are investigated by using the Runge-Kutta method. The results show that the higher Fe concentration, the lower Cu concentration and the weakly oxidized crystal are available for enhancing the saturation space-charge-field of the deeper traps center.

Optical Computerized Tomography is a technique which is famous for real-time, stable and non-contact characteristics in various flow fields' diagnosis. As a result, it shows superiorities in many domains, including the aerospace survey and the measurement of the thermo physical parameters. Due to most of the traditional reconstruction methods of OCT are based on 2-D Radon Transform, they are pseudo three-dimensional in essence. That is to say, the flow field is divided into several parallel slices firstly, and then, the stack of tomogram slices is subsequently used to compute the 3-D representation. However, all the flow fields own real three-dimensional character. Therefore, in this paper, based on the 3-D Radon Transform, the optical interferometry is studied on the model of the volume CT. Meanwhile, the sufficiency condition of accurate reconstruction is studied. Besides, the transform reconstruction algorithm for volume OCT is also presented and verified by simulated experiments. In a word, this study will be better to visualize and display flow fields.

Holographic volume gratings as diffractive elements have much practical and more potential applications, such as spatial filters, attenuators, modulators, imaging lenses and so on. The reflection volume gratings have more higher wavelength selectivity than transmission gratings and is more suitable for spectral selectors. A type of photosensitive-refractive glass, silicate glass doped with silver, cerium, fluorine, and bromine, was fabricated at our lab and the basic holographic performances of the PTR glass are experimental measured in this paper. Holographic volume grating were recorded in the photosensitive-refractive glass sample by exposured to the interference pattern of a He-Cd laser operating at 325nm and 442nm respectively. A feasible experimental strategy for readout this kind of grating by invisible or longer wavelength light is presented based on the theory of coupled waves.

The discrete layer peeping (DLP) algorithm has been widely used to synthesize the fiber Bragg grating for the inverse scattering problem. The synthesis is useful both as a design tool and for characterization of already fabricated gratings with complex profiles. In the paper, the error sources of the discrete layer peeping algorithm, including the resolution, and the bandwidth, are analyzed. We choice different resolution and different bandwidth to calculate the reflection spectrum of fiber Bragg gratings with different length of the fiber Bragg grating, separately. We find that the synthesized reflectivity can all be synthesized when the resolution is different, but the length of the fiber Bragg grating required to synthesize the reflectivity is longer as the resolution increases. For one target reflection spectrum, we also find that the length of the fiber Bragg grating required to calculate the reflectivity with different bandwidth is almost same, and a deviation between the target reflection spectrum and the calculated reflectivity decreases as the resolution increases. The resolution and bandwidth required for a certain level of accuracy will depend in general on the bandwidth and the fine structure of the initial target reflection spectrum.

It is difficult for the traditional phased array radar to process large array-element and high time-bandwidth-product signal in real time. An optical architecture of implement true time delay adaptive beamforming based on Stimulate Photon Echoes(SPE) is introduced. The principle of how to implement a true time delay based on SPE phenomenon with its theory models is established. the method of how to implement variable time delays using laser beams modulated by linear frequency chirped pulses is discussed, the relationship between chirp bandwidth and delay step is demonstrated by simulation results. As a result, it allows to filter thousands of simultaneous AOAs with 30 GHz dynamically in both spatial and spectral domains, which can be used to adaptively steer a large RF phased array antenna toward the direction of interest while minimizing the effects of unwanted interference signals.

In this paper a dynamic diffusion model is presented in order to describe the monomer diffusion and photopolymerization during the grating formation in photopolymers. We have presented a simplified model before it, which did not consider the dynamic process of monomer polymerization. In this paper a dynamic diffusion model is presented which consider the polymerization rate of monomer is change with time. Monomer concentration will decrease because of photopolymerization, and the polymerization rate of monomer will also reduce with the decreasing of monomer concentration. So the polymerization rate of monomer should be a variable parameter. In this paper the polymerization rate of monomer is corrected, and the experimental data is fitted with this dynamic diffusion model, a perfect result is got, and the parameters were got by fitting experimental data. The theory good agree with the experimental results, it proves that this dynamic diffusion model is excelled than the simplified model.

A red-sensitive photopolymer material sensitized by azure II is fabricated and its holographic storage characteristics are studied. The experimental results show that this kind of material has high diffraction efficiency (the maximum value 56%), high exposure sensitivity (5.2×10^-3 cm²/mJ) and large refractive index modulation (1.6×10^-3). The analog image generated by a spatial light modulator (SLM) is stored in this medium, the transmission and reconstruction images have a good fidelity. It shows that this photopolymer material has the potential for high-density volume holographic storage.

The wavelength and defocus margins for collinear holographic data storage system are theoretically analyzed based on the first Born approximation and the scalar diffraction theory. Explicit expressions for the decay of diffracted signal in the center of the detector plane with the shift of the reading wavelength and with the defocus of the disc are presented. The expressions predict that the defocus margin is independent of the media thickness while a thicker disc leads to a narrower wavelength margin. Simulation results show that the wavelength margin of collinear holographic scheme is larger than that of the conventional 2-axis holographic scheme. The influences of the properties of reference pattern on both margins are also discussed.

In this paper, we demonstrate that a simple and practical phase-shifted fiber Bragg grating (PSFBG) operated in reflection can provide the required spectral response for implementing an all-optical Hilbert transformer (HT), including both integer and fractional orders. The PSFBG consists of two concatenated identical uniform FBGs with a phase shift between them. It can be proved that the phase shift of the FBG and the apodizing profile of the refractive index modulation determine the order of the transform. The device shows a good accuracy in calculating the Hilbert transform of the complex field of an arbitrary input optical waveforms when compared with the theoretical results.

A new method of using a cascaded long-period fiber grating (CA-LPFG) as the spectral filter in the ytterbium-doped mode locking in the normal dispersive regime are proposed. The CA-LPFG was fabricated in a single mode fiber at wavelength of 1064nm using a CO₂ laser based system. A stable mode-locking laser output at wavelength of 1034nm was observed and measured in the normal dispersive regime. In comparison with the conventional interference filters or fiber Bragg grating filters, the CA-LPFB can provide not only an all-fiber low-loss but also a transmission mode.

The optical pickup unit is a kind of mass-produced product as well as a diffraction-limited micro-optical system. Thus the optical elements are assembled serially in the production line, and its fabricating and assembling errors should be controlled to achieve a diffraction-limited focus spot on the disk. And the reflected light from the disk on the photo detector would be converted and processed in the servo control system and evaluated using the electrical evaluator. Thus a correlation between the electrical evaluator and the spot intensity should be considered when setting the testing standard for a production line. In this paper, the optical pickup is measured using a spot analyzing system. Its electrical signals are described in the evaluator. The optical system in the optical pickup would be divided into two testing parts: base part and focusing part. The base part includes the laser diode, collimator, prism, quarter-wave-plate, beam splitter and reflective mirror; while the focusing part has objective lens, phase plate, wave-plate, and so on. The focus quality is measured using the spot analyzer. Then these optical pickups are processed to get the electrical signals directly from the evaluator. Finally the parameters achieved using these two systems are compared and its correlation are investigated. This method is verified when designing a DVD production line and might be useful in establishing the standards for a new optical pickup.

In this paper, we examine whether the use of a two-dimensional finite impulse response (FIR) filter in two presently available recording/reproduction methods, the Off-axis method, results in an improvement in the signal quality. The linear minimum mean square error (LMMSE) method is first tested to examine its effectiveness in optimizing the coefficients of the FIR filter. Subsequently, the real-coded genetic algorithm (RCGA), which has the capability of searching a wide range of coefficients, is applied and the result obtained is compared with that for the LMMSE method to see if the coefficient evaluation leads to a local solution or the minimum solution. We also applied quadratic minimum mean-square-error (QMMSE) Equalizer as a nonlinear equalizer.

One of the problems that affects the practical use of holographic memory is deterioration of the reproduced images due to aberration in the optical system. The medium used in holographic memory systems must be interchangeable, and hence, it is necessary to clarify the influence of aberration in the optical system on the signal quality and perform aberration correction for drive compatibility. In this study, aberration is introduced in the reference light beam during image reproduction, and the deterioration of the reproduced image signal is examined.

In this paper a new scheme for fibre fineness measurement is proposed by incorporating image processing into a power-spectrum analysis method. In this scheme micrographs of fibre, pre-processed for noise suppression, are loaded to a SLM for the measurement, and their power spectrums are acquired by a high-resolution CCD camera. The principle of the scheme and the parameters of the optical system are discussed. The result of a numerical simulation agreed well with the calculation, which demonstrated the feasibility of this scheme.

Based on double random phase encoding method (DRPE), watermarking technology may provide a stable and robust method to protect the copyright of the printing. However, due to its linear character, DRPE exist the serious safety risk when it is attacked. In this paper, a complex coding method, which means adding the chaotic encryption based on logistic mapping before the DRPE coding, is provided and simulated. The results testify the complex method will provide better security protection for the watermarking. Furthermore, a low-noise multiple watermarking is studied, which means embedding multiple watermarks into one host printing and decrypt them with corresponding phase keys individually. The Digital simulation and mathematic analysis show that with the same total embedding weight factor, multiply watermarking will improve signal noise ratio (SNR) of the output printing image significantly. The complex multiply watermark method may provide a robust, stability, reliability copyright protection with higher quality printing image.