This PDF file contains the front matter associated with SPIE Proceedings Volume 6832, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Light-emitting diodes (LEDs) have the potential to become the main light source for the advantages of low energy consumption, being environmental friendly and long lifetime. However so far the brightness of LEDs is not sufficient for many applications due to low light extraction efficiency resulted from total internal reflection of the emitted light at semiconductor/air interface. To overcome this problem, fabricating 2-dimensional photonic crystals (PhCs) on the surfaces of LEDs is considered as one of the most effective ways. At present, the method of fabricating PhCs is primarily through e-beam lithography and ion-beam etching. Such processes are complicated and unsuitable for low cost mass production. In this paper we propose a novel method of using holographic and wet etching processes to fabricate PhCs in p-contact ITO layers of LEDs. The PhC patterns are firstly fabricated in photoresist layers coated on LEDs, using holographic approach, then acid solution are used to transfer the patterns into ITO layers. The experiments of adopting different etching solutions and etching rates were carried out and the results were compared, in order to find out the best etching condition. Experimental results demonstrate that solution HCl : HNO3 : H2O made less damage to photoresist mask and can better control the etching depth in ITO. PhCs with different lattice constant and depth were fabricated to obtain the best PhC parameters for higher light extraction. 30% increase of external quantum efficiency has been achieved in the experiment.

Glancing angle deposition (GLAD) is a thin film fabrication method providing dynamic control over the internal columnar microstructure of the deposited film. Using the GLAD technique it is possible to control the porosity of the coating allowing precise tailoring of the optical properties. Therefore, in a single material system, the refractive index profile of the film can be engineered to create a variety of multilayer structures. The focus of this research is on the optical properties of these structured thin films. When the structure is periodic, incident radiation is subject to constructive and destructive scattering which lead to photonic bandgap effects. Also of interest are the optical properties of aperiodic systems, such as the Thue-Morse multilayer, which are deterministic but non-periodic. The complex structural correlations in aperiodic systems lead to interesting bandgap-like properties. Applying the GLAD technique, periodic and aperiodic optical lattices are fabricated with titanium dioxide, a dielectric material commonly used in optical coating devices. The bandgap properties of these systems are investigated using transmittance spectroscopy and transfer matrix calculations.

Parallel femtosecond laser processing using a computer-generated hologram displayed on a spatial light modulator is demonstrated. The use of a spatial light modulator enables to perform an arbitrary and variable patterning. This holographic femtosecond laser processing has advantages of high-speed and high light-use efficiency. A critical issue is to precisely control the intensities of the diffraction peaks of the computer-generated hologram. We demonstrated some methods for the control of diffraction peak intensity. We also demonstrate the laser processing with two-dimensional and three-dimensional parallelism using the Fourier hologram.

Photonic crystals are emerging as new generation devices with lots of promising applications. Holographic fabrication of photonic crystals has become choice of many due to its associated flexibility. The paper reports about our efforts on holographic recording of various 2-D periodic structures in photoresist material and conversion of these to metallic structures, through electroforming. A He-Cd laser (442 nm) was used to record the basic diffractive structures by two beam interference technique. These types of structures can exhibit specific bandgap behavior and endurance in high power laser applications.

We present an analysis of the reconstruction through any intermediate plane by using the cascaded Fresnel diffraction integrals. The realization of the integral with the single fast-Fourier-transform (FFT) imposes inherently the constraints on the pixel resolution and the field of view of the computation window in the intermediate plane. On the other hand, according to the optical diffraction field of the band-limited object, the size of the diffraction field including most energy exhibits a change with the intermediate plane in a different way. Since the field of view of the computation window is usually smaller than the corresponding optical diffraction field, then the simply cascaded FFT-Fresnel diffraction integral algorithms will lose the resolution and degrade the image quality. It is proposed to improve the reconstruction by compensating the field to be close to the optical diffraction field and using the new field as the computation window in the intermediate plane. The numerical simulation and the experimental data-based calculation are performed and demonstrate our proposal.

The different reconstruction algorithms are investigated and the reconstructed images are presented in lensless Fourier transform digital holography. The most employed three algorithms, all based on the fast-Fourier-transform, are: the convolution algorithm, the angular spectrum algorithm, and the Fresnel algorithm. With the convolution algorithm and angular spectrum algorithm, there is an optimal reconstruction distance where the pass-band range of the transfer function is the largest. Then the whole reconstructed image with the highest resolution can be acquired. When the distance is different from the optimal distance, the size of the reconstructed image may vary with the distance and may disappear from the field of view in some cases. In order to obtain the whole image, two methods are proposed. However, at this time the resolution of the reconstructed image becomes lower. When the distance is smaller than the optimal distance, the whole image can be obtained, but the resolution of the image also decreases. The Fresnel algorithm is performed by using a single fast-Fourier-transform. With Fresnel algorithm, the same reconstructed images can be obtained with the different reconstruction distances and the reconstruction is better than with the convolution algorithm and the angular spectrum algorithm.

Based on the traditional basic theory for the making of the phase hologram, the digital phase hologram is studied in this paper. The experimental results demonstrated that, in the forming of digital phase type hologram, there exists a constituent parameter that corresponds to the exposure time of the traditional phase type recorded by holographic plate. By choosing the proper constituent parameter, the object wavefield can also be reconstructed from the digital phase hologram. In this paper, the forming of the digital phase hologram and how to choose the constituent parameter are presented, finally, the comparison between the digital amplitude holograpy and digital phase holography in theory simulation under the same condition and the experiment verification are given out.

Large amounts of communication bandwidth and memory space is occupied to transmit and store digital hologram on account of its enormous data volume. It is necessary to compress the information of digital hologram for effective transmittance and storage. After theory of off-axis hologram is studied, it is found that at most half of the information is useful for reconstructing image. A new method is proposed to compress the information, according to the spectrum character of off-axis hologram. The sampling frequency is reduced by shifting the useful information of digital hologram from high-frequency section to low-frequency section. Therefore, the information is compressed. The detailed procedure is expressed as follows. (1) To filter the hologram with a high-pass filter, whose cut off frequency is equal to the difference between frequency of reference beam and the highest frequency of object beam. (2) To multiply every row of the filtered hologram by a cosine sequence, whose frequency is equal to the difference between frequency of reference beam and the highest frequency of object beam. (3) To filter the processed hologram with a low-pass filter. (4) To subsample the hologram with a sampling frequency as four times as the highest frequency of the object. As thus, the digital hologram is compressed to half size of the original one at least. Moreover, higher compression rate will be obtained if the subsampled hologram is compressed with other methods. The theoretical analysis and experimental results are presented.

Surface contouring by digital phase-shifting holograph system based on the LC-SLM is proposed in the paper. Special phase-shift is introduced in the reference beam by changing code pattern displayed on the LC-SLM. And the reconstruction quality of complex amplitude of object wave has been improved greatly. The surface contouring measurement can be realized by means of phase change introduced by rotating the object beam.

Phase modulation characteristics of subwavelength metallic square holes are investigated for 2D imaging purpose. Based on Maxwell equations, the transmission model of three-dimension subwavelength metallic holes is founded by a mode expansion technique. The relationship between the widths of the holes and the phase from -π to π is established when the thickness of metallic film is given. Then the influences of coupling electromagnetic (EM) fields as well as the incident angle on phase retardation are investigated and calculated through varying the center distance between double holes. A slab lens is demonstrated by using hole-array formed on a metallic film, which verifies the theoretic analysis.

Electromagnetic diffraction of optical waves at a subwavelength aperture becomes a focus of recent research interest in order to explain theoretically and experimentally the transmission enhancement of arrays of nano-size holes in metallic screens. Some theories propose that the surface waves exited at a subwavelength aperture by diffraction is propagated to the neighboring aperture and interfered with the incident optical beam at that aperture, resulting in enhancing or suppressing of the transmitted energy through the aperture. In those theories one considers implicitly the interference of the two waves in the exit side of the aperture. However, in the entrance side of the aperture we note that the surface waves and the incident beam have perpendicular wavevectors and orthogonal polarizations before being coupled into a slit. It is then important to investigate how this interference occurs with mediation of mutual conversion between the surface waves and bulk waves at the nano-slit. We find that a part of the surface wave energy scattered by the slit edge leaks into the slit and induces diagonal electrical charge dipole, which radiates new bulk waves and surface waves on the slit's side-walls. Multiple reflection Fabry-Perot resonators are formed in both horizontal and vertical directions over the slit, depending on the slit's width and depth. We demonstrate the hypothetic interference between the fields induced by the surface waves coupled into the slit and the normal incident wave, which induces also electric dipoles and new surface waves at the slit. Our calculation fits well with the experimental results. The work is significant for development of the optical diffraction theory on the metallic nano-size apertures.

A biochemistry nanosensor based on hybrid metallic nanostructure array was put forward in this paper. The hybrid metallic nanostructure array consists of two types Ag nanostuctures, spherical and pyramidal structures with the same period. A biochemistry sensor experiment is demonstrated by detecting the transmittance spectra of hybrid metallic nanostructure using Sciencetech spectrophotometer. The wave peaks of transmittance spectra have shifts when the metallic periods and the refractive index of Ag nanostuctures are different.

We describe a convenient way to generate arbitrary vector beams by using a spatial light modulator, based on interferometric superposition of two orthogonally polarized beams. In our constructed optical setup, the SLM is used to produce a computer-generated holographic grating that diffracts a linearly polarized incident light into the +1st and -1st diffraction orders with desired wavefronts. After the two diffraction beams pass through two quarter wave-plates, the left- and right-handed circularly polarizations are yielded, respectively. Then a Rochi grating is utilized to recombine the two beams into single one such that any desired polarization configuration is achieved. We demonstrate the versatility of our method through optical experiment, in which a variety of polarization beams are realized. By making use of the incident wave with helical phase, our technique can produce both cylindrically symmetric and asymmetric polarizations. To the best of our knowledge, the experimental realization of cylindrically asymmetric polarization is reported for first time. We also study the focal properties of vector beam through a high numerical aperture lens. Starting from Richards-Wolf vectorial diffraction theory we calculate the focal field distribution and obtain some interesting focal volume structures, such as flat-topped focus, doughnut focus with special dark volume structure.

We introduce and compare two methods to produce the phase-shift patterns, which are widely generated in the near-field lithography, in the optical far field. The key component of the two methods is a phase-only diffractive optical element, a similar function found in the maskless lithography. The technique to produce a smaller feature size was a major improvement beyond the diffraction limit.

In this work, the transverse optical trapping of spherical particle with strong absorption is studied in geometrical optics model by numerical simulation. In our work, the exact expressions of wave vector are used instead of traditional approximate expressions, and the transverse optical trapping force acting on a spherical particle due to strong absorption is calculated when the particle is illuminated by a focused Gaussian beam of TEM₀₀ mode. The calculated results show that stable transverse optical trapping positions only exist when the center of the spherical particle is located in front of the focus of the beam. Our results also reveal that the trapping positions are decided by the radius of the beam waist ω0. The magnitude of transverse optical trapping force and the stiffness of optical trapping decrease with the increase in ω0.

The dual-beam fiber-optic stretcher has been used for studying cell's viscoelastic properties under optical radiation pressure [1, 2]. In this paper we study the coupling from one fiber to another by a Red Blood Cell swollen to a spherical shape, and captured by the two countpropagating laser beams. First, we compute the photonics force distribution on the cell's surface using the ray optics, and then the deformation of the cell using the mechanics of the linear membrane theory of thin shell. Finally, we compute the coupling coefficient between the two fibers by the deformed ball lens of ellipsoidal shape. As the cell acts as a thick lens here, its spherical and defocus aberrations are estimated and included in the calculation of the coupling coefficient [3]. This technique could allow obtaining the visco-elasticity of a large number of cells by rapidly measuring the light coupling efficiency as a function of the laser beam power and the fiber end-to-fiber end separation, but without imaging and measuring the cells deformation.

In this invited paper, I will first review some of the fundamentals of optical scanning holography. I will then include some of the recent publications on optical scanning holography.

In this paper, a new method, which synthesizes the technology of computer graphics (CG) and holographic integral photography, is proposed to realize the holographic display of virtual 3D scene in large size. In this method, elemental stereographic images of 3D scene are computed by a virtual holocoder instead of using pickup process. And then, the color of elemental stereographic images is separated by computer and three tricolor elemental image series are printed by high graphics printer. The printed image series can be integrated into the previous 3D scene with a lens array whose optic parameters match to the virtual holocoder. If the image series are illuminated by laser, the virtual 3D scene is reconstructed by coherent light, and then the reconstructed scene can be recorded by single wavelength color holographic technology in large size.

The comparison of bi-grating diffraction imaging and the displaying of ordinary transmission hologram with white light source, shows two different imaging methods have same essence, but different characteristic. In these two processes of imaging, the light-wave of the object has been diffracted twice, both methods have to combine the dispersed image of different wave length, so both of them have to employ the spectral combination characteristic of grating. The bi-grating imaging equation not only is fit for the bi-grating imaging process, but also has guidance meaning in ordinary transmission hologram displaying with white light source and the aid of grating.

The backlight unit should be used to illuminate the liquid crystal display (LCD) panel, and the typical light throughput is around 5% for the color LCDs. This insufficient light efficiency is predominantly related to the use of the color filter. In this paper, a three-step Talbot grating based on the fractional Talbot effect to realize the color separation in the color LCD is proposed in order to increase the light efficiency. Simulation shows that, when the incident light is a uniform plane wave, the light efficiency of 85% is obtained, which is far higher than that of using color filter's 33% theoretically. This design is insensitive to the displacement along the direction of the movement of color separation plane and the change of RGB wavelengths, and it is also insensitive to the grating's steps height. In addition, the Talbot grating is feasible for fabrication.

A real-time miniaturized three-dimensional endoscopic imaging system basing on Dammann grating array illumination is proposed. The system consists of two endoscopic channels that one channel is used to project an array structured light generated by Dammann grating on an object and the other is used to obtain images from the object to measure its surface profile. Using the special designed Dammann grating, it is very simple to generate an array structured light, couple it into the endoscopic channel and project it on an object. The measured images are processed with a standard image processing procedure and the surface profile is extracted by Fourier transform profilometry algorithm. With the development of computer hardware and fast image processing algorithms, the imaging system can acquire real-time data and dynamically process three-dimensional measurements. The system was evaluated in 3-D measurements of several objects with known geometries. The results show high accuracy of the imaging system and its potential applications in clinic and biology research.

A subwavelength transmission polarizing beam splitter (PBS) of deep-etched binary silicon grating at wavelength of 1550 nm is described, and TE-polarized and TM-polarized waves are mainly diffracted in the -1st and 0th orders, respectively. In order to achieve high extinction ratio, the grating depth and period are optimized using the rigorous coupled-wave analysis (RCWA). And the maximum extinction ratio of the rectangular PBS grating can reach 301.97 with the optimum grating period of 1291 nm and depth of 2.04 μm, the efficiencies of TE-polarized wave in the -1st order and TM-polarized wave in the 0th order are 60.07% and 73.09%, respectively. Holographic recording technology and inductively coupled plasma (ICP) etching could be used to fabricate the silicon PBS grating. Though the diffraction efficiency of the silicon PBS grating is not so high, since the silicon material is widely-used and easy to obtain; the grating structure is compact and the fabrication technology of this material is well established for mass production, the deep-etched silicon transmission PBS grating should have potential applications in optical communication systems.

Phase-shifting is one of key technologies in the digital holography or interferometry. Exact and stable phase shifts play an important role in the experimental results. Computer-generated holograph phase-shifting unit based on LC-SLM can produce phase shift with repeatable and high stability. In the system, it is very crucial to encode the computer-generated holograph on LC-SLM. This paper investigates phase-shifting precision and stability as well as diffraction efficiency by using various encoding methods in theory and experiment. The work in the paper establishes foundation that computer-generated holograph phase-shifting unit based on LC-SLM can be applied in the digital holography and interferometry system.

In this paper, we design phase-only and quantized diffractive optical elements to transfer a field with circular Gaussian intensity distribution to an expanded squared uniform distribution based on the Fresnel diffraction theorem. The simulated annealing algorithm was used to design these elements. Many different cost functions were defined, applied and compared in this algorithm. Besides, we found that dark area expansion in the target patterns can improve the uniformity of designed results. However, there are no improvements when the bright area is smaller than an eight in one dimension of the total diffraction field. In addition, the uniformity can be improved at the expense of decreased diffraction efficiency.

X-ray transmission gratings (TG) have attracted much interest because of its wide use in x-ray telescope, synchrotron radiation facilities, and target diagnostic in inertial confinement fusion, etc. In this work, a 200 nm period master TG to diffract x-ray in the energy range 0.1-8keV has been successfully fabricated by electron beam lithography followed by gold electroplating. In fabrication processes, 500 nm resist was exposed by focused electron beam on polyimide free-standing-membrane coated with a Cr/Au plating base. According to numerical simulation, the proximity effect due to electron back-scattering from the substrate can be sharply reduced because of the thin polyimide free-standing membrane substrates. PMMA resist was chosen due to its high resolution and good performance in subsequent processes. After delicate dose test and shape modification of the proximity effect caused by electron front-scattering, resist grating bars with 95 nm width and 200 nm period were achieved. Subsequently, resist patterns were transferred to gold layer by electroplating. In future work, with this master mask of TG, thousands of TG to diffract x-ray can be sufficiently replicated using x-ray lithography.

Ion-beam etching blazed flat-field concave diffraction gratings (FFCG) to achieve high diffraction efficiency is a difficult task. This paper presents a new method to fabricate convex holographic gratings as master gratings for making FFCG. This method makes it convenient to fabricate blazed FFCG with corrected aberrations and uniform predetermined blaze angle over the grating surfaces. It can also be adapted to the commercial fabrication process. This method could be briefly described as follows: First, we make a convex grating using holographic recording method. The grooves are determined by the interference fringes of two spherical waves, one of which is divergent coming from the back side of the substrate, and the other is convergent coming from the front side. Leading-term aberrations can be corrected by optimizing the center positions of the two sphere waves. Second, the exposed convex grating is etched by ion beam to make a blazed convex grating. In this step, it is much easier to get a uniform blaze angle over the surface of a convex grating than over the surface of a concave grating. At last, the etched convex grating is used directly as a master grating to replicate blazed FFCG. An optimized example for a specific system structure is given in this paper. The advantages and difficulties of the method are discussed.

To alleviate the difficulty of ion beam etching, it is essential to acquire the low gradient holographic photoresist grating masks as well as the high gradient ones (i.e. the rectangular holographic photoresist grating masks). According to the ion beam etching experiments, the low gradient photoresist grating masks can effectively eliminate the redeposition. The control of the profile of holographic photoresist grating masks is investigated in this paper. Considering the effects of developing time and temperature of the developer on the response of photoresist and adopting the combination of computer simulation and experiments, a low gradient photoresist grating mask: 30% duty cycle at bottom and 65° gradient can be fabricated. The study indicates the increase of the developing time causes the diminish of the threshold volume of exposure while the increase of the slope of the linearity of photoresist response; the rise of the temperature of the developer leads to both the increase of the threshold volume of exposure and the slope of the linearity of photoresist response. As a result non-1:1 interferential exposure and low-temperature development are required in the fabrication of low gradient photoresist grating masks. The 1:7 interferential exposure and 15°C- development have been adopted in this experiment.

Holographic photopolymers become promising materials for future production of holographic devices. And the mechanism of hologram formation in photopolymers has been broadly studied. In this paper we present a simplified model in order to describe the monomer diffusion and photopolymerization. According to this model, the main effect the modulation of refraction index comes from the intensity of recording beams and fringe spacing during recording. So we quantitatively analyzed the effect of recording intensity and fringe spacing on diffraction efficiency, and carried out validating experiments with a novel blue-green sensitized photopolymer. Holographic gratings were recorded with different recording beam intensities and different fringe spacing respectively, and corresponding diffraction efficiency were obtained. By fitting the experimental results to the model, we obtained the material parameters, such as diffusion time constant, polymerization coefficient. The experimental results indicated that a higher recording intensity resulted in a faster growth of grating and lower saturated diffraction efficiency. And saturated diffraction efficiency increased with the increasing of fringe spacing. These agreed well with theoretical expectation. This study improves the understanding of recording process and consequently allows building more accurate holographic components in the photopolymers.

The holographic storage characteristic of a new kind of water-resisting photopolymer is studied; and studied it's photoperceptivity and application in many aspects. The photopolymer is composed of two dyes which is sensitive to red and blue wavelength. This kind of photopolymer is water-resisting and its post retreatment is simple. The volume shrinkage mass of this material is also small. We have used this material to make gratings successfully; we settled the problem of spreading this photopolymer to soft film for storage.

Digital holography is a whole-field, non-contact, and highly sensitive interferometric imaging and testing technology. It is more suitable for microscopic measurement owing to digitalization and flexibility in holograms recording, storage, reconstruction and transmittance. This paper analyzes the factors which lead to the phase aberrations in the off-axis lensless Fourier transform digital holography firstly. Then a method, which is obtained by borrowing ideas from T. Colomb, is presented to correct the phase aberrations automatically during the numerical reconstruction. This is implemented by multiplying a phase mask directly with the reconstructed wave field. The phase mask is obtained by an iterative procedure computing automatically without the pre-knowledge of the physical parameters, such as the off-set of the reference point source and the recording distance. This method enables one to reconstruct the relative correct and accurate phase-contrast image, even in the presence of the noise, which is needed to be smoothed by a median filter. In order to achieve an accurate phase image, the procedure described here is applied iteratively, starting from the initial values provided by the first evaluation. We present and analyze the simulation results of the phase images based on a special three-dimensional micro object. The results show that for a weak noise the above method is very effective; while for strong noise the common phase-unwrapping method must be applied. This indicates that it is very important to record high quality hologram and to suppress the noise in phase data.

A method for the measurement of low-density microporous polymeric foams with digital microscopic image plane holography is studied. An image plane hologram of microporous foam is recorded in an optical system of a Mach-Zender interferometer by CCD sensor, and the magnified image, which contains the quantitative information of the intensity and the phase of the microporous foam, is reconstructed numerically from the captured single interference pattern by twice fast Fourier transform and digital filter processing of frequency spectrum. And the morphometry and the pore diameter of the microporous foam under test can be obtained. A theoretical analysis has been performed and experimental results of the polymeric foam are also given. The experimental results show that the method presented in this paper is feasible, easy in data processing.

This paper discussed the measurement error of digital holographic 3D surface shape caused by imprecise measurement of the incident angle and the tilt angle of object light illumination in theory. The result showed that the error caused by the tilt angle is much greater than the incident angle. Then a method to accurately calculate the object light's tilt angle by detecting the interference field of reference plane is proposed based on the above discussion. Finally, the feasibility of the method is proved through a 3D surface shape detection experiment.

Based on Fresnel diffraction theory, the point spread function (PSF) of the off-axis lensless Fourier transform digital holographic system with pre-magnification is deduced for the first time to the best of our knowledge. The limited lateral resolutions of the digital holographic systems with and without pre-magnification are analyzed in detail. For lensless Fourier digital holography, the expression of the limit resolution is obtained by use of Rayleigh resolution criterion and the PSF of this system. The obtained resolution is different from others in coefficient. Moreover, we propose new recording conditions with which the higher resolution can be achieved. The experimental results of a USAF test target demonstrate the correctness of the theoretical analysis about the lensless Fourier digital holography. For digital holography with pre-magnification, the limit resolution is also analyzed in detail. The results show that the imaging resolution is associated with the parameters of MO and CCD, the recording condition and the light wavelength. If the imaging resolution of CCD is higher than that of MO, the resolution of the whole system is dependent on the numerical aperture of MO. On the contrary, the resolution is dependent on the imaging resolution of the CCD. It is best to make the imaging resolution of MO approach the resolution limitation and the imaging resolution of CCD equal to or higher than the resolution of MO slightly, which can be implemented by decreasing the distance between the object and MO and decreasing the recording distance properly. The simulation results indicate the correctness of the theoretical analysis.

Based on the point spread function of the off-axis Fresnel digital holographic system with pre-magnification, the phase aberration introduced by microscope objective is obtained. Using a collimated light as reconstructing wave, the phase aberration introduced by the difference between the reconstructing wave and the reference recording wave is analyzed. This method is very simple, and it is very different from the one proposed by T. Colomb et al. The phase mask that can be used to compensate automatically the phase aberration in the phase reconstruction is obtained. According to the principle of digital holography, it must be pointed out that for Fresnel digital holography, the recording distance must be determined accurately before compensating automatically the phase aberration. This is done by an automatic focusing procedure, which is based on image-gray-entropy-method. The simulation result for a special three-dimensional micro object, which is polluted by a random noise, is presented. The percentage error of the reconstructing distance obtained by the focusing procedure is below 0.6 for SNR = 25. Then an automatic aberration compensation procedure, which is the same as that one proposed by T. Colomb et al., is applied to reconstruct the phase image. The results show that for a weak noise the above method is very effective; for a stronger noise the procedure described here is applied iteratively, starting from the initial values provided by the first evaluation; while for a very strong noise the procedure fails at all. Moreover, after applying a median filter to the primary reconstructed phase image, the aberration of the phase image obtained by further iteration decreases, at the same time the noise is strengthen.

We explored the reaction mechanism of the dual-wavelength water-resisting photopolymer. The photosensitive material which was sensitive to red and green light was synthesized, using the complex photo sensitizer. The photosensitivity was improved and the scope of the photosensitive spectrum was broaden. We also studied the influence of the ingredient on the holographic performance of the polymeric material. Further studies on the influence of the solution preparation on the quality of the hologram was made, too. The appropriate exposure time and disposal way were obtained through experiments. The experimental result indicates that this hologram of the dual-wavelength water-resisting photopolymer is damp-proofing and non-active. It is easy to preserve in any environment. It needn't chemical treatment to manufacture hologram applying this prescription. The diffraction efficiency would be increased obviously by heating. Providing ideal storage material to the manufacture of the holographic element, the prospect of the appplications would be more extensive.

Angle amplifier of laser beam scanner is a widely used device in optical systems. Volume holographic optical elements can be applied in the angle amplifier. Compared with the traditional angle amplifier, it has the advantages of high angle resolution, high diffraction efficiency, small size, and high angle magnification and flexible design. Bragg anglewavelength- compensating recording method is introduced. Because of the Bragg compensatory relation between angle and wavelength, this device could be recorded at another wavelength. The design of the angle amplifier recording at the wavelength of 514.2nm for the working wavelength of 632.8nm is described. An optical setup for recording the angle amplifier device is designed and discussed. Experimental results in the photorefractive crystal Fe:LiNbO₃ demonstrate the feasibility of the angle amplifier scheme.

Owing to the high Bragg selectivity and capacity of multiple recording, volume holography has been widely investigated for devices such as wavelength filters in wavelength-division multiplexing fiber communication systems in recent years. Transmission-Writing and Orthogonal-Readout scheme (TWOR) has been proposed for making wavelength filters in holographic media. In this paper, experiments on wavelength selectivity of volume gratings with TWOR scheme are successfully conducted for the first time to our knowledge. Readout by wavelength-tuning showed that a 3-dB bandwidth of 0.5nm was achieved. The experimental results agreed well with the expectation of 2-D coupled-wave theory, and verified the feasibility of TWOR scheme.

According to the theory of electric-optical effects to design the slice pattern, size and the appropriate combination of chip, the γ₆₃-transversal electric-optical modulator (pockells box) of KDP crystal is designed in the article. The high semiwave voltage of KDP crystal (~8000V) will be decreased to several hundred voltages which can be used in practical application and the temperature stability of this electric-optical modulator is improved. The experimental result shows that the signal transfered by laser is not affected with the changing of the working temperature of this electric-optical modulato. While the He-Ne laser (λ=0.6328μm)is used to the communication, the semi-wave voltage will be reduced to 687.5V practically and the coefficient of eletric-optical is γ₆₃=11.98×10^-12m/V. It is consistent with the theoretical value.

This paper introduces a new and simple concept of moire effect. A circular grating placed at Talbot planes can achieve beam deflection measurement in real time. It is not only used for 2-D beam shift measurement at every point, but also used to measure the angle and plane parallel degree of optical element and birefringence measurement of the optical material.

This paper presents a new method to measure the characteristic parameter of the laser holographic anti-counterfeiting label, with less dependency on the stability of source light. The He-Ne laser, having 5% relative instability, was used as the light source. Based on the nature that one beam of light can be divided into two beams at a fixed ratio, the source light was divided into the reflex and the transmission at the fixed ratio by a piece of glass. As the label was scanned automatically, the intensities of the reflex and the diffraction were measured online and in real time to get the SNR. The data table for contrast was given, which showed the differences between the real value and the calculated value of the intensity of the transmission as the incident beam. The measurement results of the SNR of 8 different versions of labels were also listed. The experimental data demonstrate that the relative error of the transmission intensity is not more than 0.29%, and that of the SNR is less than 2.0%, which is approximately half the error of the original method.

In this work two liquid crystal spatial light modulators (LCSLMs) were applied to encode a reference beam and holographic storage of a set of encrypted data pages that formed the object beam. The SLMs were developed by converting two 84×48 pixels mobile phone displays and were set in transmissive mode. Fourier holograms were recorded in a red sensitive photopolymer emulsion (SM635C of POLYGRAMA, Brazil), coated on a glass substrate. While replay the reconstructed data page, recorded against a specific reference beam was captured by using a CCD camera and processed in a personal computer for decryption. The encoded reference beam forms a unique key to the individual hologram recorded through shift multiplexing. Diffraction efficiency of holograms was calculated and was found to be about 45%. The system offers a very cost effective solution for secure data storage and retrieval and can be used for storing valuable software, security documents etc.

High efficiency solar cells are emerging as a viable tool for tapping solar energy. Such cells need cool light to be concentrated on them for high conversion efficiency. Conventional refractive and reflective light concentrators, with sun tracking systems, are bulky and heat the solar cell due to single focus convergence of heat and light radiation. HOEs are emerging as an active candidate for making new generation light concentrators. In this paper we report the design, development and characterization of a multi beam reflection HOE for light concentration. The proposed design of single focus, multiple exposed reflection element with wavelength selectivity can be used to avoid sun following system.

Scanning and interference imaging spectrometer are widely used in earth observing, microscope imaging, etc. Motion mechanisms are utilized in all these simple imaging spectrometers, which make the system big, expensive and unstable. A novel static non-imaging spectrometer is introduced specifically. 2D (two-dimension) static multi-channel spectral measurement is realized in this spectrometer, utilizing 2D hadamard matrix code mask and 2D detector. The hadamard matrix is different from traditional S circular code. The orthogonal property of hadamard matrix is utilized, and with special transform negative codes in hadamard matrix are also realized. Basing on this non-imaging spectrometer static imaging spectrometer is developed. First 2D imaging spectrometer can be divided into many 1D ones which work independently. The 1D imaging spectrometer is obtained with position information added into the hadamard coding system in dispersive direction. To get 2D imaging spectrometer, extend the coded aperture: put some masks together in non-dispersive direction. According to this model, the spectrum of an image instead of a slit can be estimated at one time. The optical system is designed to simulate the imaging spectrometer. Compared to the simple scanning imaging spectrometer the simulated result shows the model's resolution can be compared to simple scanning spectrometer, but the scanning time of simple scanning imaging spectrometer is about 3 times of our simulation. At last some implementation issues are mentioned.

The cubic phase mask is an approximate theoretical solution for extension of depth-of-field (DOF) in the computational opto-electronic imaging system. In the practice, it does not provide an infinite depth of field. Especially the cubic coefficient needs to be determined for a given optical system and a requested extension of the DOF. Many other approaches using a variety of masks have been proposed. In this paper we propose a polynomial phase mask, which is still separable in the Cartesian coordinate system, as the cubic mask. The phase contains 16 terms of odd powers and was optimized by the simulated annealing. The cost function was designed for invariance of the MTF curves with a full range of depth-of-field of ±200 μm in a biomedical microscope. This number of polynomial coefficients provides the optimization with a necessary number degree of freedom. We introduced a target MTF to assist the simulated annealing, which was defined iteratively from the ideal MTF to a more practical and achievable target MTF. Our result is compared with that of the recently published approaches. The experimental results with digital restoration of images using the invariant MTF are also shown.

In order to improve the quality and solve the problem of low speed of image reconstruction in the traditional optical computerized tomography (OCT) when the data acquired is incomplete projection, the multiple constrained of genetic algorithm based on algebraic iterative was proposed. Generally speaking, under the condition of multiple-objective optimization, the common extreme point for all the objective functions doesn't exist. So we can achieve the preferable compromise in the contradictions of multiple objectives. In this article, there are three constrained conditions. The first one is the maximum entropy criterion which is used mostly to solve the problem of OCT image reconstruction when the data acquired is incomplete projection recently. The second one is the minimum criteria of peak value which is introduced to suppress noise effectively and ensure the gliding property of the image reconstruction, because of the first one leading to noise amplification during the iterative process. The last constrained condition is the minimum criteria of the difference between the projection again of image reconstruction and the original projection. The concept of penalize-function is introduced into the genetic algorithm, which would transform the constrained optimization problem to unconstrained. It is clearly demonstrated from the experiment results that the algorithm reconstruction technique can efficiently improve the quality of images reconstruction of the incomplete projection data.

A method for producing one-step holographic stereogram is presented. Combining computer-based digital image processing technology, two kinds of stereogram, made of slits or dots respectively, are discussed. The stereogram produced can offer a combination of large viewing zone and minimal image distortion, depending on alterable parameters in the image processing program. Hologram-recording experiments are carried out, and then process and results are given. Since the techniques described are applicable to mass produce large scale stereogram automatically, primary designing of stereogram-printing equipment, both 'slits' and 'dots' systems are studied.

A new type of holographic screen used to display projected 3-dimensional (3D) images with large viewing angle and relatively high brightness is presented. The screen is 2-dimensional hexagonal lattice relief in micron-scale lattice period, fabricated in plastic sheet using holographic technique and pattern replication method so that the fabrication of the screen is fast and cost effective and large-size screen can be obtained. Theoretical analysis and experimental results demonstrate that larger lattice period generates more diffracted rays thus provides larger viewing anlge and brighter image. 45° horizontal and 30° vertical viewing anlges have been achieved and the images with parallax have been observed. The screen has the potential of being applied for 3D holographic movie display and 3D art exhibition.

Extending the depth of field (DOF) of incoherent optical systems has been an active research topic for many years, and the extended depth of field (EDOF) system can be used in many fields. We developed a novel circular pure phase plate to extend the DOF by a factor of 4 without decrease of optical power in image plane. The plate is divided into several equal-area annular zones and placed in the exit pupil of a standard optical imaging system. The annular zones alternately eliminate the influence of different defocus beside the ideal Gauss object plane. The comparisons of the MTF and PSF curves between two systems show that the system employing the phase plate has a large DOF while preserving an acceptable resolution. Also, the images captured by the system don't have to be restored by a digital filter before next processing. And the simulation of imaging a spoke target in several defocused condition also confirms the EDOF of the imaging system. The DOF can be adjusted by two parameters of the phase plate: defocus compensation parameter and zone number. We gave the relation curves between system's performances and parameters of the plate.

The polarization-based digital holography of Fresnel-zone-plate (FZP) convolution without motion is proposed. This method focuses mainly on imaging of two-dimensional objects embedded in highly scattering media. The key of the method is that the uniformly distributed light source is utilized to make many FZP projections superpose on an object in a classical incoherent correlator. In this way a hologram of the object is obtained by convoluting its intensity distribution with the FZP intensity distribution without relative motion. A method called composite hologram is applied to improve the low signal-to-noise ratio due to extremely weak signals submerging in large backgrounds. Especially, the configuration of this method is designed to avoid time-consuming. The polarization gating is used in order to extract the weakly polarized light from the highly scattered light. In experiments, the degree of polarization of circularly polarized light is maintained better than that of linearly polarized light in highly scattering media. Circularly polarized light is, accordingly, used in practice. The experiments on a 0.4-mm-diameter metal wire embedded in Intralipid-1% phantom are carried out. The outline of the metal wire can be still distinguished, although the reconstruced image becomes blurred as the thickness of cuvett increases to 30 mm. An attempt to apply this method to image the metal wire embedded in chicken tissue sections also be implemented. The reconstructed images can be distinguished in depth of 10 mm. The experimental results demonstrate that the method has potential applications in imaging of objects embedded in highly scattering media.

One of the more intriguing of solar collection techniques, holographic concentration, has been addressed in many ways, but it has so far met with only limited success. The major attraction of holography is that unlike conventional concentrators, the holographic concentrator can track the sun across the sky while remaining completely stationary. A simple system using holographic Fresnel lenses (HFLs) was proposed in this paper. We present the theoretical analysis and the technique for fabricating HFLs used for solar concentrator. Several HFLs fabricated using corresponding recording geometries, resulted in a combined device that collects light at any angle, with each lens responsible for gathering sunlight for a certain portion of the day. Three HFLs with different fringe pattern were achieved, which operates in the morning, at noon and in the afternoon, respectively. The primary experimental results of the concentrator were presented, which effectively concentrates the visible spectrum over a 60 degrees daily angular variation. Several advantages of the holographic concentrator we obtained include longer lifetime, low cost, and the small size of a flat piece of film compared to a mirror or lens. The dispersive characteristics applied to photovoltaic power generation would offer a novel type of generator with high conversion efficiencies.

A liquid crystal display (LCD) recently comes into common use. It is possible for this display unit to provide the same size of displaying area as the image screen on the panel. Thus the conventional display can show only one screen, but it is impossible to enlarge the size of a screen, for example twice. To enlarge the display area, the authors have developed an enlarging method of display area using a mirror. Our extension method enables the observers to show the virtual image plane and to enlarge a screen area twice. In the developed display unit, we made use of an image separating technique using polarized glasses, a parallax barrier or a lenticular lens screen for 3D imaging. However, each technique has a defect at viewing an image. In the glasses method, an observer needs to wear the special glasses for a viewing screen. The slit or lens sheet reduces the resolution in half. To solve these problems, we develop a new virtual display system using a unidirectional diffusing image screen.

The conventional display can show only one screen, but it is impossible to enlarge the size of a screen, for example twice. To solve this problem, the authors presented an enlarging method of display area using a mirror. Our extension method enables the observers to show the virtual image plane and to enlarge a screen area twice. Although the displaying region is doubled, this virtual display could not produce 3D images. In this paper, we propose a 3D imaging display with an extended region using an angle-controlled unidirectional 4-views display.

The conventional display can show only one screen, but it is impossible to enlarge the size of a screen, for example twice. Meanwhile the mirror supplies us with the same image but this mirror image is usually upside down. Assume that the images on an original screen and a virtual screen in the mirror are completely different and both images can be displayed independently. It would be possible to enlarge a screen area twice. This extension method enables the observers to show the virtual image plane and to enlarge a screen area twice. To enlarge the screen region twice, it is necessary to prepare a mirror. This mirror and the imaging plane of an original display must be placed at right angles to each other. Therefore, the mirrors take up much space in front of display. To solve this problem, we have developed a new reflective mirror using a holographic optical element.

The reconstruction of digital hologram is a key topic in the research of digital holography, which is maturely developed for the reconstruction of two-dimensional image. Recently, the reconstruction of three-dimensional image has attracted much more attention. In this paper, we apply the two-wavelength digital holographic contouring method to obtain the three-dimensional image, the basic idea of which is to reconstruct the shape through the phase difference that can be numerically calculated by Fresnel diffraction algorithm. Considering the fact that the obtained phase is wrapped on the interval (-π, π], and the unwrap algorithm always fails for the object with large height steps or spatially isolated areas, we adopt the two-wavelength digital holography to provide an equivalent longer wavelength such that the obtained phase is continuous everywhere. The experiment results prove the feasibility and efficiency of the method.

In this paper, we calculated the numeric results of diffraction field in space of X-ray (λ=4.5nm) Fresnel zone plate based on angular spectrum method, analyzed the axial and radial distribution patterns of X-ray Fresnel zone plate. The Full Width at Half-Maximum (FWHM), Depth Of Focus (DOF) and Strehl efficiency of focus spot were studied. Discussed the relationships between FPZ's design parameter and focus spot properties. At the condition of λ=4.5nm and the outmost width Wn=50nm, the size of focus spot is proportional to the outmost width, and increase slowly with the increase of number of zones and focus length; the DOF of focus spot increase at first; when the focus length increased to 40µm, the DOF incline to a constant; the focus spot's Strehl efficiency increased slowly with the increase of number of zones and focus length.

In this paper, we propose an improved hologrpahic technique for fabricating 2D hexagonal and 3D hexagonal packed photonic crystals (PhCs). The key element in the fabrication system is an off-axis holographic lens group (OHLG) consisting of three off-axis holographic lenses. Under the illumination of an expanded laser beam, three collimated beams can be generated by the OHLG to form a uniform hexagonal lattice pattern without using a collimating lens. The utilization of OHLG in the system eliminates the noise in the interference pattern resulted from the collimating lens so that lattice quality is enhanced. The system is simple and stable and can be used to fabricate large-size PhCs.

We discuss the diffraction of waves due to the periodically corrugated boundary of vacuum and a linear, homogeneous negative refraction index metamaterials (NIM). We show by numerical simulation that the grating surfaces can give rise to a well-defined diffracted beam in addition to the negatively refracted beam. The direction of the diffracted beam is consistent with elementary diffraction theory; however, the coupling to this higher order beam is much larger than would be the case for a positive index material (PIM). To explore the properties of diffracted beams in a negative-index sample, we simulate a wave incident on the interface between a NIM grating and free space. The numerical study provides an indication of the relative coupling of the incident wave to the zeroth and first order beams.

A new method of digital image processing is developed for the correlation recognition of aviation photographs under volume holographic correlator. The physical characteristics of semivariogram of the image are analyzed according to spatial statistics, which suggests the principle of the image segmentation, including the dimension of the templates, the space between each template and the image restoration. Then the residual space of each template is calculated directly based on the 2D-images to enlarge and to scatter the differences between the correlativity. After that, the residual spaces are reconstructed to form the final set of templates. Finally the proposed method is tested on a series of aviation photographs. The experimental results come with rather higher precision as well as rather lower computational complexity, which supports the real-time capability of the optical correlation recognition of aviation photographs under volume holographic correlator.

Traditional dispersive spectrographic systems usually base on slit imaging. The entrance slit can ensure a remarkable spectral resolution but a loss of system throughput and vice versa, thus this kind of instruments can't achieve Jacquinot advantage and Fellgett advantage simultaneously and statically. To derive a high gain model for the stationary dispersive systems with these two advantages, traditional single-slit and the multi-slit spectrographic systems were studied. A method for single channel spectrum abstraction in a multi-slit spectrographic system was derived. This method demonstrates that if each individual slit in a multi-slit system possesses a transformation form of orthogonal independent column codes, the spectrum of each individual slit can be abstracted from superposed spectrum, spectral resolution of equivalent single-slit system is obtained and the system achieves dual advantages. This high gain computational system model is applicable for almost all kinds of existing dispersive spectrographic systems. Furthermore individual coded slits can be integrated as a coded aperture to increase system's integration level and reduce off-axis aberration. Based on the derivation of theoretical model, two kinds of coding forms' mathematical models were studied. To verify the derived theory, a testing system with a specially designed flat-field holographic concave grating and a coded aperture of order 16 Hadamard matrix form was set up. The experiment indicated that although optical aberration and other system noise were involved, this high gain system model could still achieve a high spectral resolution of 0.4nm as single-slit system, while remarkable system etendue (8X) and SNR (4X) were also obtained, which proved the correctness of the theoretical derivation.

Multimode interference (MMI) couplers, based on the self-imaging effect (SIE), are accepted popularly in integrated optics. According to the importance of MMI devices, in this paper, we present a novel method to design and fabricate MMI couplers. A technology of maskless lithography to make MMI couplers based on a smart digital micro-mirror device (DMD) system is proposed. A 1×4 MMI device is designed as an example, which shows the present method is efficient and cost-effective.

Polarization is one of the key features of light wave. generation of light beams with required polarization is an issue worth studying. In this paper, we propose a new method by which arbitrarily polarized light beam can be formed in specified output plane. Several simulated results about axial-symmetric polarization are obtained by use of our proposed scheme and the scheme proposed by. [J. Phys. D: Appl. Phys. 38 (2005) 827-832]. It is clear that simulated results with use of our scheme are more agreed with the ideal beam. In addition, several other polarized beams are also simulated. From all simulated results, they are all showed that a beam with arbitrary polarization distribution can be obtained by use of our proposed scheme.

In this paper, we designed a single binary optical element (BOE) which can perform collimating, dispersing and focusing. Therefore, we can use it to replace grating and focusing lens in the mini-spectrometer. With just one major optical element, the anti-vibration ability and optical stability of portable mini-spectrometer can be improved in big scale. At the same time, optical set-up for mini-spectrometer also becomes much easier since fewer elements are involved. Space saving due to this BOE offers opportunities for further resolution improvement. Besides this, this binary optical element can be produced in very low cost compared to the cost of those gratings and lenses, since binary optical elements are much easier to be duplicated for the sake of development of optical plastics and nano technology.

The short wavelength, high brightness and good spatial coherence of soft x-ray lasers make them ideal sources for the diagnostics of dense plasmas. As a widely used diagnosing tool in the research of laser-produced plasma, interferometry has many advantages in the accurate measurement of the plasma electron density because it directly gives refraction index mapping from the interference pattern processing. The electron density gradient and electron density of larger variety plasma will be probed by the soft X-ray diffraction grating Mach-Zehnder interferometer (DGI). At the wavelength 13.9nm which our DGI uses, we fabricate a laminar grating used as the splitter grating. Its groove density is 1000g/mm, groove depth is 13nm, duty cycle is 0.4±10%. The zero and first diffracted order beams have an equal metrical diffraction efficiency about 25 percent at 81.3 degrees, and the maximum of the product is 7.6 percent at 81.2 degrees. The results illustrate the laminar grating is suitable for being used as a new pattern splitter grating at the wavelength 13.9nm.

In this paper, we introduce the potentialities of the digital hologram for the three-dimensional shape measurement from numerical reconstructed image. The image processing of the Fresnel digital hologram recorded by CCD sensor and the algorithm for 3d shape reconstruction is taken into account. Firstly, we stitch a series of small digital holograms to obtain a hologram with larger size. Secondly, the reconstructed image sequences of different depth planes are obtained by numerical reconstructing hologram. Finally, the depth information of each sample point of object is gained by algorithm of focus measure evaluation, in which the maximum focus measure of a region is found by the grey level variance of image sequence. The basic principle of this technique and its experimental verification are presented.

The multiple phase screens and Fourier-transform algorithm for numerical simulation of beam propagation through atmospheric turbulence is important for imaging problems, lidar or laser radar. In this work Fast-Fourier-transform-based model of phase screens are used to simulate the propagation of a radar beam. The refractive-index power spectrum used for phase screen generation is the so-called modified atmospheric spectrum defined by L C Andrews. The standard compensations used to correct the undersampling at low spatial frequencies are improved, and the limitations and numerical requirements for a simulation of given accuracy are established. By using the improved algorithm, the scintillation index of gaussian beams propagation through atmospheric turbulence is studied. Comparisons of simulations with analytic results are presented. The on-axis theoretical scintillation index is compared with simulated results at different ranges and good agreement is shown between numerical simulation and theoretical results.

A new technique is proposed to obtain a real color hologram with a large viewing angle by the combination of computer and optical method. Two steps are followed to finish this technique. (1) Computer-generated hologram H₁ is yielded. According to the theory of light propagation, and taking full advantage of computer-generated hologram, object lightwave distribution of three monochromatic Fresnel holograms with a large dimension is computed in different area of the same plane. Object lightwave distribution is folded into smaller area based on the method of mirror images. High density holograms H_1r, H_1g, H_1b are generated after the holograms are exported and microfilmed. (2) A rainbow hologram H₂ is generated by optical ways. In the recording procedure, two parallel mirrors with appropriate parameters must be matched in the experiment system. In terms of the reversibility of light path principle, an image with a wide viewing angle is reconstructed by reversing the reconstruction lightwave. The principle of the proposed method and the experimental result prove that the technique achieves a color reconstructed image with a wide viewing angle of 14° . It is very clear that the stereoscopic effect of the reconstructed image is increased.

A fundamental problem in optical and digital holography is the existence of speckle noise in the reconstructed image. Many approaches have been carried out in order to overcome this problem. In this paper a new technique to reduce the speckle noise is proposed based on the physical nature of speckle noise. The illumination direction of the object beam is changed to provide a different phase information for the same recorded object in an off-axis digital holographic setup and the holograms are recorded with different illumination directions. Then the intensity information of the reconstructed images is superposed and averaged to reduce the speckle noise. The theoretical analysis and experimental results are shown to valid our proposal. They prove that the technique can effectively reduce the speckle noise without ruining the object information.

A novel holographic light-guide plate (HLGP) for the illumination of liquid crystal display is proposed in this paper. The holographic film designed for red light (632.8nm) is introduced to the top surface of the wedge-shaped light-guide plate. The backlight system with the HLGP can achieve large gain in uniform illumination. The enhanced illumination uniformity of the emanating light is measured in the experiments.

Photon sieve is a novel diffractive optical element modulating either amplitude or phase which consists of a great number of pinholes distributed appropriately over the Fresnel zones for the focusing and imaging of light. Photon sieve has the advantages of the diameter of pinholes beyond the limitation of the corresponding Fresnel zone width and the minimum background in the focal plane. Furthermore, photon sieve can be fabricated on a single surface without any supporting struts required unlike the Fresnel zone plate. Photon sieve can be used as EUV telescope for solar orbiter, space-based surveillance telescope operating at visible light, or other imaging components. Photon sieve can also be used as one of the promising lithographic tools for nanoscale science and engineering to obtain the lower cost, higher flexibility and better resolution. The approaches to enhancing imaging resolution of photon sieve are presented in detail. According to Fresnel-Kirchhoff diffraction theory, the diffractive field of photon sieve is described by means of the discrete fast Fourier transform algorithm. The related contents include the calculation of point spread function, the suppression of side lobes, the imaging bandwidth, the physical limit of resolution, and the diffraction efficiency. Imaging properties of photon sieve are analyzed on the basis of precise test.

A novel photopolymer based on polyvinyl-alcohol for holographic storage was fabricated. The material with riboflavin (RF), methylene bule (MB), erythrosin B (ErB) as the photosensitizers for holographic storage has a broad absorption spectrum range (more than 500nm). The photopolymer can be sensitized by the whole visible light, and that will improve storage capacity and density of the holographic storage greatly, especially under the short wavelength recording. Photo-induced reaction processes in the photopolymer and phase grating of index modulation for holographic storage were studied. The surface structure of the grating and the images of reaction processes were scanned by SEM (Scanning Electron Microscope). The experimental results are compared with the kinetics theory of the polymerization and they are fitted well. Furthermore, the grating constant can be estimated from grating images which were scanned by SEM. Some holographic characteristics of the photopolymer were analyzed. Using a standard holographic setup, we recorded unslanted diffraction gratings.The material has high maximum diffraction efficiency (≥68%), good sensitivity (≥3.03×10^-3 cm²/mJ), and high index modulation (≥4.58 ×10^-4) when its tickness is about 300μm. Two dimentional simulate images generated by SLM (Spatial Light Modulator) were stored in the film, and the reconstructed data pages had good fidelity. The results show that the material has a better potential in holographic storage.

Holography has been widely applied in industry measurement, especially in 3D non-contact testing. Combining a high resolution charge-coupled device (CCD) with a phase modulating liquid crystal display (LCD), holographic interferogram recording and display could be realized by digital holographic technique. Digital holographic technique has a great number of important and practical applications. In the conventional holography hologram was detected and reconstructed by the holography panchromatic plate, or the photoconductive thermoplastic film, or the BSO crystal and etc. But in the digital holography--the numerical version of the conventional holographic technique, hologram is digitally detected by CCD and then displayed on the computer monitor. By reconstruction, the hologram is writted into LCD, then illuminating the LCD with the reference wave, the tested object may be reconstructed optically. In this paper the application technique of CCD/LCD in holography is theoretically studied and the bottle techniques have been solved. According to the resolving power of the CCD and LCD, the angle between the two interfering waves should be less than 3° for recording the interference fringes with high spatial frequency. The simple and prospective optical architecture is perhaps Twyman-Green interferometer for easy to adjust the required small angle between reference and tested object waves, and also optical path deference for satisfying the requirement of spatial and temporal coherence. The disadvantages of CCD/LCD digital holographic technique is the small separation angle between zero-order and ±1-order diffraction. In order to separate ±1-order from zero-order diffraction, the minimum fringe spacing formed by the interference of object wave with reference wave should satisfy the sampling theorem. This decides a relationship between the size of object and the recording distance, which will be discussed in detail in the following text. And also discussion about the experimental research of LCD in digital holography would be included in our paper.

This paper proposes the Fuzzy Control Iterative Algorithm (FCIA) for the design of diffractive optical elements for laser beam shaping. Firstly, to improve the poor uniformity of output laser beam obtained by the G-S algorithm, we put forward the Profile Smoothing Algorithm (PSA), which is effective in improving beam uniformity but slack in controlling the Mean Square Error. Then we put forward the Fuzzy Control Iterative Algorithm, which combines PSA and G-S algorithm by fuzzy control theory. Taking advantages of GS and PSA, FCIA can decrease both Mean Square Error and nonuniformity of output beam simultaneously. Computer-designed result shows that an extremely ideal output beam is derived by using FCIA. The Mean Square Error is 0.75%. The nonuniformity is 0.46%. And the energy converting efficiency is up to 94.91%. This paper affords a novel algorithm for the design of diffractive optical elements for laser beam shaping.

The focusing properties and focal depth of amplitude modulation Gaussian beams are investigated. Numerical results show that the intensity in the focus plane is circle shape in the low numerical-aperture optical system, while the intensity distribution in the focal plane is ellipse shape in high numerical-aperture optical system due to contribution of depolarized longitudinal component. Focal spot size and focal depth can be adjusted by changing geometrical parameters and the modulation amplitude power n of Gaussian beams. The tunable range of the focal depth is very considerable.

In recent years, a new fiber position sensor based on wavelength encoding plane variable-line-space gratings is developed and has attracted more and more interest. In this paper the theoretical background to the fiber position sensor concept is briefly described. The large slope groove density distribution variable-line-space grating with holographic recording is used in fiber position sensor. The preliminary results obtained were quite noteworthy. Due to the unevenness of the incident light intensity in different wavelength, the diffractive intensity of different position change quickly. The diffraction wavelength curve of the system is given. The resolution of the position sensor is also discussed in this paper.

Using DMD system to make circular gratings and arrays is based on the character of Space Light Modulation (SLM) of DMD chip which can control the reflected lights based on the input figures' gray-scale. Firstly, circular gratings are simulated in a computer with some simulation software programmed in VC. Then, the figures are inputted in the DMD chip. With the character of SLM of DMD chip, the reflected lights can be controlled according to the circular gratings' gray-scale. The circular gratings can be obtained after being developed, fixed and etched. Many contrast experiments are carried out to confirm the technique parameters of circular gratings, as well as fabricate the two levels, four levels and array of circular grating. By use of this method, we are capable of making low-cost but useful circular gratings easily. Their levels and radii can be controlled, which will be suited for many optical systems. Compared with scoring mechanically, lithography and e-beam etching, binary optical methods are more convenient, efficient and low-cost.

It is known that rectangular grooves profile and various duty cycles (line to pitch) are required to attain maximum efficiency. The gold transmission phase gratings have been fabricated using holography and ion-beam etching techniques. The latent image monitoring technique and real time end-point detection technique were utilized to improve control of the shape of grooves and duty cycle during exposure and development, respectively. It is difficult to produce gratings with larger duty cycle in photoresist on gold for standing wave, nevertheless it is revealed in our work that the duty cycle can be more than 0.4 for the case for photoresist on gold substrates if development is stopped where the slope of the monitoring curve begins to drop off, not at the peak of the diffracted signal. In ion-beam milling, the influence of redeposition on the shape of grooves and duty cycle has been overcome by using a thin mask of Chromium with a comparatively low ion-etch rate and tilting and rotating substrates beneath the ion beam. Finally, some gold phase gratings with the duty cycles in the range of 0.25-0.45 have been obtained, whose duty cycle value is about 0.45, and their grooves profile is trapezoidal profile whose left and right facets are both more than 83 degrees approximately.

Hot embossing has become a key technique in the replication of microstructures. In particular, the hot embossing of diffractive gratings into thermoplastic has been widely used in the mass production of holograms. The process involves the transfer of a surface relief structure from a plate to a substrate by high temperature and pressure applied to an intermediate film. So in this paper a novel printing process for replication of holographic lens used as multiplexer/demultiplexer has been demonstrated. Advantages of this technique are the low cost and ease of processing. Some analysis indicates that for WDM in fiber communication, the thermoplastic polycarbonate is a good choice. In the primary experiments, the optimum temperature and force for embossing were 130 degrees and 5Mpa. The optimal thickness of a nickel shim used in the mesne process was established to be 60 micron. The lens arrays were uniformly embossed over the entire area of the thermoplastic which was typically 8×8. Minimum diffraction efficiency of the embossed lens in thermoplastic layer is about 50% (-3dB). High quality replicas of device have been fabricated using this process. Printing via an embossing process offers the possibility of mass production of demultiplexer easily and cheaply compared with conventional demultiplexer.

The uniformity of ion beam current density profile has been amended by changing the flow of the gas and making a new beam channel. The platform scanned in the horizontal orientation in this experiment, so the horizontal ion beam current distribution had hardly any effect on the etching uniformity and amending the ion beam current density profile in the vertical orientation was sufficient for the purpose of plat etching profile. The ratio of the ion source's working gas inputs has some effect for the uniformity and a ratio of 6.50sccm: 8.00sccm: 9.60sccm of the three gas inputs flow1: flow2: flow3 will lead to a more uniform profile. According to the horizontal distribution and the original vertical ion beam current density distribution measured by Faraday Cup, a new beam channel was made. The uniformity of ion beam current density profile is enhanced from ±4.31%to ±1.96% in this experiment.

Multilayer dielectric grating plays an important role in the laser inertial confinement fusion, which is fabricated by using holographic lithography and ion beam etching. In this paper details the reactive ion beam etching of multilayer dielectric grating with SiO₂ as the top layer. The etching of SiO₂ was carried out by a radio frequency reactive ion beam etcher with CHF₃ chemistry to increase the etch selectivity and get a high fidelity grating pattern transfer from photoresist into SiO₂ coating. The photoresist gratings with different profiles as masks were used to create SiO₂ corrugations with different profiles separately. The etching results were analyzed in detail, including the facet and redeposition effects. In conclusion, it is essential that the photoresist grating mask should be high and steep enough to get SiO₂ grating with vertical profiles. The multilayer dielectric grating with SiO₂ as the top layer exhibited an efficiency of about 95% in the - 1 order at TE polarization of 1 064 nm light at Littrow mounting.

Holographic technologies for optical memories and interconnection devices have been studied actively because of high storage capacity, many wiring patterns and high transmission rate. Among multiplexing techniques such as angular, phase code and wavelength-multiplexing, speckle multiplexing technique have gotten attention due to the simple optical setup having an adjustable random phase filter in only one direction. To keep simple construction and to suppress crosstalk among adjacent page data or wiring patterns for efficient holographic memories and interconnection, we have to consider about optimum randomness of the phase filter. The high randomness causes expanding an illumination area of reference beam on holographic media. On the other hands, the small randomness causes the crosstalk between adjacent hologram data. We have proposed the method of holographic multiplexing, shift-phase code multiplexing with a two-dimensional orthogonal matrix phase filter. A lot of orthogonal phase codes can be produced by shifting the phase filter in one direction. It is able to read and record the individual holograms with low crosstalk. We give the basic experimental result on holographic data multiplexing and consider the phase pattern of the filter to suppress the crosstalk between adjacent holograms sufficiently.

This paper proposed a method by using integral imaging for computationally reconstructing three-dimensional (3D) images from different viewing points without introducing additional system complexity. In this method, the process of 3D scene sensing is accomplished by using a microlens array to obtain elemental images. The multi-viewing-points reconstruction process is carried out by computationally simulating optical reconstruction. The prototype displays differently directional views with a horizontal or vertical angle pitch of 3°~1°, when the depth range of object is from 150mm to 450mm. The viewing angle of one image point is about 53°. By optimizing the parameters of imaging system, the angle pitch would satisfy the requirement of practical application. The experimental results proving the effectiveness of the method are given.

Holographic grating can be used widely in optical fields, especially in wavelength division multiplexer and optical fibre network. In this paper, a new kind of water resisting photopolymer which is sensitive to the red light of 632.8nm and green light of 514.5nm is made into double holographic grating by exposure twice. The resolution of this grating is above 4000line/mm. The principle of manufacture and technology of the new style grating is simple; it doesn't need the second treatment. The grating has many other merits, such as lower cost high diffraction efficiency, better stability and so on. Based on the study, the holographic grating can be used for wavelength-division demultiplexer for it is lower loss and narrow-band width.