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Issue 7 ， 2007
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Form error of optical surface repaired by wet-etch figuring
Abstract：A wet-etch figuring method is presented to repair the form error of optical surface to avoid the subsurface damage and surface pollution caused by traditional polishing technology. The Marangoni effect is used to control the dwell time and dwell area of chemical solvent,and the optical surface is repaired by program control of a digital system. The surface roughness of the optical surface before and after processing is measured by a profilometer. Experimental results show that the form error of the optical surface can be decrease from 1.22 λ(λ=632 nm) to 0.66 λ by the method in many wet-etch and a little wipe off surface figuring,but the optic surface roughness is invariable in test.The results also indicate that the method can improve the laser threshold of optical element.Keywords：optical element;wet-etch figuring;surface form error repairing;Marangoni effect;roughness- 37
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Published：2020-08-12 -
Improvement of high frequency dynamic performance of actuator in optical pickup by finite element and sensitivity methods
Abstract：After analysis on the high frequency resonance mechanism of a actuator in optical pickup, the effect of parameters on the high frequency dynamic performance are studied by Finite Element Emulation(FEE). The FEE together with the sensitivity analysis method are used to analyze structure parameter’s contributions to the second order resonance frequency, and then the structure is optimized. The result shows that the second resonance frequencies in the focusing and tracking directions are increased by 6.6% and 17.5% respectively, thus the dynamic performance of the lens actuator in high frequency is improved obviously. The method can also be used in other optimum design fields.Keywords：optical pickup;actuator;high frequency dynamic performance;sensitivity analysis method;finite element emulation- 53
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Published：2020-08-12 -
Dwell time algorithm based on matrix algebra and regularization method
Abstract：A novel algorithm to solve dwell time based on linear algebra (matrix-based algorithm) is discussed,in which math model changes the fabrication process from convolution to matrix product,so that the calculation of the dwell time becomes a solution to linear equations. Traditional factorization methods such as Gaussian elimination and total least squares can not be used because the linear equations are severely ill condition. So, the Tikhonov regularization is used to solve the ill-posed problem caused by meterage error,and the regularization parameter is determined adaptive method without any prior knowledge. By comparing with different algorithms, the advantages of the matrix-based algorithm are obviously with the precision enhancing 30%. In the end, an error data is solved with actual parameters using the matrix-based algorithm. The simulation results show that the convergence rates of the PV and RMS values can reach up to 0.48 and 0.62, respectively. The matrix-based algorithm can satisfy the requirement of fabrication very well.Keywords：aspheric processing;dwell time algorithm;regularization method- 50
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Published：2020-08-12 -
Quantitative research on higher order harmonic suppression in 17~33 nm with different thickness Al filters
Abstract：With 840 l/mm transmission grating (made in house) behind the exit of Spherical Grating Monochromator (SGM) in Spectral Radiation Standard and Metrology (U27) beamline, the dispersion of exit beam and the contributions of different orders were analyzed. The results of higher order harmonics suppression by different thickness Al filters were given in the region of 17~33 nm. The results show that when the thickness of Al filter is 400 nm, and the wavelength between 17~33 nm, the contributions of higher orders to the detector signal are restricted to less than 2%, and the Photon Diode (PD) intensity is strong enough. After being corrected by quantum efficiency of the PD detector, the higher order contributions are less than 0.6%, which is important for calibration absolute reflectivities of multilayer and detector.Keywords：synchrotron radiation;higher order harmonics suppression;Al filter- 70
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Published：2020-08-12 -
Flat-top interleaver of cascaded M-Z interferometer with 2×2 and 3×3 fiber couplers
Abstract：An all-fiber flat-top interleaver of Cascaded M-Z Interferometer (CMZI) using a 2×2 and two 3×3 fiber couplers with approximate rectangular wavelength response was developed.The relationships among the coupling ratios of the couplers, the length difference of interference arms, and the intensity transmission spectrum were analyzed. The results indicate that a uniform flat-top spectral response can be obtained by the configuration when the length difference of interference arms and the coupling coefficient of the couplers are some certain values and the passband and stopband of optical interleaver can be improved remarkably. Compared with conventional CMZI, the most advantage of the present method is that the coupling ratio of couplers can be controlled accurately. Finally,a novel structure of interleaver is fabricated using fused biconical taper technics in experiment. The experiment results agree with the analytical ones well.Keywords：applied optics;comb filter;Mach-Zehnder interferometer;interleaver;directional coupler- 33
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Published：2020-08-12 -
Design of a photographic objective using cubic phase plate
Abstract：An optical/digital imaging system is proposed. This system uses a cubic phase element and digital image processing to increase the depth of focus in keeping the same illumination and resolution. Two positions, -1.6 λ(λ=550 nm)and in focus, are analyzed in simulation. Then both modulate transformation function (MTF) and the relationship between the MTF and focus in a longer depth of focus are given. Using the imaging simulation tools CodeV, the simulation images are obtained. After digital processing, the final image is also obtained. Experimental results show that this new optical/digital system can increase the depth of focus by 6 times at least.Keywords：photographic objective;optical design;Phase plate;Depth of focus- 48
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Published：2020-08-12 -
Design of an optical system for UV curing source with LED array
Abstract：A novel system mainly consisting of multipath controllable constant current source, UV LED spatial array and optical system for UV curing source with LED array was presented.Among them, UV LED spatial array is used to increase the radiation and uniformity of the source. Based on analyzing the UV curing source structure, an optical system was designed. The design method and several design cases, and simulations for optical system with the Light Tools software were also presented. Experimental results show that UV irradiance of the LED spatial array source designed by this method can reach 200 mW/cm2, and the radiation in the radiating area maintains even and stable, which can meet the needs for source in UV curing process.Keywords：UV curing;LED spatial array;optical design;Light Tools- 54
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Published：2020-08-12 -
Middle infrared continuous zoom optical system
Abstract：For cool 320×240 detector with staring focal plane array, a middle infrared continuous zoom a optical system was presented. The optical system using optical configuration of reflect mirror fold is composed of a zoom object lens system and a secondary imaging system, including seven lenses and two reflectors. Based on the practical requirement and feature parameters of detector, the optical design parameters were given. Using zoom system principle and optical design software, the schematic diagram, modulation transfer function (MTF) curve, spot diagram, and Root Mean Square (RMS) value of the spot diameter were investigated. Finally, the cold reflection ray-tracing of short EFL end was studied and the correlative schematic diagram was also given. The results indicate that the optical system with 3.7~4.8 μm spectral region can realize 50~500 mm continuous zoom and satisfy 100% cold shield efficiency. It has the advantages of simple structure, high image quality, short zoom path and smooth zoom locus. And moreover, only one aspheric surface is adopted in the system, so the system is in a low price and easy to machine and adjust.Keywords：infrared optical system;continuous zoom;optical design- 50
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Published：2020-08-12 -
Structural design and mechanism analysis of a valveless piezoelectric pump with single bimorph and double chambers
Abstract：A valveless piezoelectric pump with single bimorph and double chambers was put forward for improving its flow rate. Some elastic curved surface differential equations of circular piezoelectric composite laminates were derived from the theory on the elastic thin plate bending with small deflection. The structure and working principle of the piezoelectric pumps consisted of one PZT bimorph to fabricate two chambers were introduced. The relations of structure and flow rate were analyzed by comparing with the single bimorph and single chamber piezoelectric pump. The valveless piezoelectric pump with single bimorph and double chambers was designed and fabricated. It has unique structure and high flux output. Experimental results show that the flow rate of piezoelectric pump with single bimorph and double chambers is obviously improved comparing with the flux output of the single bimorph and single chamber piezoelectric pump.Keywords：single bimorph and double chambers;valveless piezoelectric pump;principle;flow rate- 38
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Published：2020-08-12 -
Study on electrode process of UV-LIGA micro-electroforming by AC impedance method
Abstract：In order to find out basis factors related with metal electrocrystallization of cathode and to take adequate measures to control electrode process of cathode, the electrode process kinetics of micro-electroforming was studied. Under provided composition of electroforming solution and technology course conditions, the electrode process kinetics of micro-electroforming Ni structure was studied by AC impedance method. The equivalent circuit of micro-electroforming system was presented. Then, the influence of agitation and leveling agent on impedance of electroforming system was analyzed based on AC impedance chart and resistance reactance frequency response. Finally, the kinetic parameter, exchange current density in electrode process was calculated. The results show that the optimization amount of leveling agent is 3 g/L by measuring impedance of solution, exchange current density is 0.171 A/dm2 under agitation and optimization amount of leveling agent conditions. The impedance of solution is decreased, and the current efficiency of cathode is increased while agitating micro-electroforming solution and using leveling agent, it can improve surface performance, tightness and uniformity of Ni microstructure.Keywords：micro-electroforming;AC impedance method;leveling agent;exchange current density- 61
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Published：2020-08-12 -
A simple and low-cost method to fabricate flexible microelectrodes for neural applications
Abstract：A simple and low-cost method to fabricate implantable flexible thin-film microelectrodes is described for neural applications. A photosensitive polyimide (Durimide 7510) is used as substrate materials instead of non-photosensitive polyimide or parylene in conventional process. A new self-shaped technique for thin-film electrode is also employed in the scheme. In addition, an easy and mild release procedure based electrochemical etch is proposed to detach microelectrodes from the fabrication substrate. The whole process using only two masks and two depositions is simple and fast, and can greatly reduce the time and cost of fabrication of neural microelectrodes. The geometrical, electrical properties and biocompatibility of the microelectrodes are also discussed.Keywords：flexible microelectrode;neural prostheses;polyimide;groove;sacrificial layer- 65
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Published：2020-08-12 -
Control for automatic rising-lowering of gyroscope
Abstract：The automatic rising-lowering system of a hanging gyroscope is designed, in which linear motor controlled by the DSP (Digital Signal Processing) is adopted to automatically rising-lowering the sensitive components of the gyroscope instead of the traditional cam gear manipulated by manpower, and the relevant software and hardware are also designed. In the determination of stability, when the pulse frequency is 26~40 Hz, the gyroscope runs stably and the unilateral swing is 94~210', when the pulse frequency is 33 Hz, the stability of lowing the gyroscope and north-finding effect are best and the unilateral swing is 105~147'. In the comparative experiments between automatic rising-lowering system and traditional manual operation, the automatic rising-lowering system shows its high stability, low repeat and simple operation. The experiment results indicate that the automatic rising-lowering system has a high stability, and can shorten the north-finding time and improve the precision of north-finding.Keywords：gyroscope;linear motor;automatic rising-lowering;Automatic control- 52
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Published：2020-08-12 -
Building method of ICF chamber center reference system and its monitoring
Abstract：A new method for building and transferring chamber center reference system for the target of Inertial Confinement Fusion(ICF) was put forward, and three sets of optical vision monitor instruments with autocollimating and microscope functions were designed and investigated. And then, the working principle and optic design were presented. Finally, the calibration method and testing results were given. The analysis results indicate that the precision of the monitoring system is above ±3.28 μm. Experimental results prove that the method of building and transferring coordinate reference system are easy to carry out and keep a high accuracy. It can satisfy the system requirements of leading physical-test target to the center of target chamber.Keywords：ICF;chamber center reference system;coordinate transfer;vision measurement;autocollimating- 76
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Published：2020-08-12 -
A high speed and high precision displacement measurement method using double grating scales
Abstract：A high speed and high precision displacement measurement method based on double grating scales was presented, and the signal’s switching and merge of double grating scales was discussed based on the analysis of measuring theory of grating scale. By analysis of the subdivision error of Moire fringe, the error of the count impulse’s switch process was decreased. A signal process circuit was designed using the programmable logic device-FPGA, and the feasibility of method was proved through the logical and timing simulation by the design software of FPGA. Experimental results show that while the maximum allowable moving speed of grating is grater than 1 m/s, the measurement resolution is 10 nm. It can satisfy the system requirements of high speed and high precision displacement measurement.Keywords：displacement measurement;double grating scale;switching and merging;FPGA- 48
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Published：2020-08-12 -
Theory and experiment on hydrodynamic suspension ultra-smooth machining for silicon wafers
Abstract：In order to realize nano-scale ultra-smooth machining for silicon wafers, a hydrodynamic suspension machining system based on robot was established,and the nanometer SiO2 suspension liquid with good dispersibility and stability was developed. By conducting experiments, the correlation between the surface roughness of workpiece and the machining time, motor rotate speed, density of abrasive particles were revealed. Experimental results indicate that the machining effects are the best when the machining time, motor rotate speed and density of abrasive particle are 60 min/s,6 000 r/min and 30 g/L,respectively. The surface roughness after machining can be 1.55 nm. Based on the conducting experiments, the machining mechanism was analyzed. The results show that the hydrodynamic suspension ultra-smooth machining for silicon wafers is the combination of mechanical impacting and chemical function. The nano-scale ultra-smooth surface of silicon wafers can be realized after hydrodynamic suspension machining and high quality surfaces without plastic deformation and damage are achieved.Keywords：ultra-smooth machining;hydrodynamic suspension;silicon wafer;removal mechanism- 49
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Published：2020-08-12 -
Variable temperature quasi-creep experiment for fabrication of microfluidic chip using Cyclo-olefin Polymer (COP)
Abstract：A hot embossing method is used to fabricate Cyclo-olefin Polymer (COP) microfluidic chip in this paper. Since temperature is the most important parameter in hot embossing process, the variable temperature quasi-creep experiment is set up to study the viscoelastic character of COP for determination of the working temperature. From a point of temperature below COP’s (Tg) temperature, applying the embossing working pressure, the temperature-deformation curve at slow temperature rising speed(1.5 ℃/min) is obtained. According to this curve, the hot embossing of microstructure under embossing reference temperature (Tr) has a high accuracy and low substrate deformatiom. Experiments show that average duplication precision is 97.6% in width and 94.3% in depth. Electrophoresis and DNA separation experiments have been done on fabricated COP chip,which shows that COP chip has excellent biologic compatibility and is suitable for biochemical analysis.Keywords：COP microfluidic chip;variable temperature quasi-creep experiment;electrophoretic efficiency- 40
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Published：2020-08-12 -
Novel 2D chaotic map based on image segmentation and image encryption approach
Abstract：A novel image encryption approach based on a new 2D chaotic map and consisting of left map and right map utilizing image segmentation was proposed. The chaotic encryption of image is realized by processing image stretch-and-fold. Firstly, a square image was divided into two isosceles triangles along the diagonal, utilizing the difference of the pixel numbers of two adjacent columns of the triangles, each pixel in a column was inserted to the next adjacent column. Then, the original image could be stretched to a line. Finally, the line was folded over to a new square image whose size was the same as the original image. The process was invertible,so that the positions of image pixels could be used in image encryption. Taking the numbers of the left map and the right map as the keys, the algorithm of the map was formulated, the method of key generation was designed and the security of the proposed image encryption was analyzed. The simulation results show that the proposed encryption approach is valid. When the key is 64 bits, the whole key space size is 1.84×1019 and the speed of encryption is 3 Mb/s. The image encryption has several advantages such as rapid speeds, high security and without message loss and it is easy for hardware/software realization.Keywords：2D chaotic map;image encryption;Chaos- 45
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Published：2020-08-12 -
Application of data fusion to acoustic holography
Abstract：A data fusion technology was proposed based on neural network and evidence theory,and a data fusion model consisting of the sensor subnet and the fusion subnet was established based on the measurement principle of acoustic holography.The sensor subnet on neural network was given to realize the map from the target characteristic parameters to the target type,so that the preliminary output was obtained. Then, the evidence theory and target information were synthesized to obtain the final identification result was obtained. Finally, an example was provided to illustrate the application of data fusion technology to the sound source identification of acoustic holography. Experimental results indicate that the identification rate of sound source is 94.2% after data fusion, It is increased by 11.7%. The application of data fusion technology can reduce the adverse effects caused by insufficient information or accidental errors and make the identification results of sound source more reliable.Keywords：acoustic holography;sound source identification;neural network;evidence theory- 39
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Published：2020-08-12 -
Method of motion object recognition based on affine invariant
Abstract：A method characterized by its excellent invariability in translation, rotation, scale and angle of view for recognizing motion object in 3D space was presented. The contour curve of object was parameterized by an affine invariable and the parameterized curve of object waiting for recognition was projected orthogonally. So it could keep better correlation with the object of the same type in store. Finally, normalized related function was regarded as the criterion of recognition. The experimental results show that the correlation of objects is over 95% in the 3D's change of pose,the proposed method can recognize objects of multiform changes with superior discrimination rate.Keywords：object recognition;affine transformation;contour curve;motion object- 55
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Published：2020-08-12 -
Lip contour description based on orthogonal transform in visual driven speech synthesis system
Abstract：In order to describe the lip contours in a lip reading system automatically and fleetly, orthogonal compression transformation was applied to the feature extraction of lip contours. Discrete Fourier Transform (DFT) and Discrete Cosine Transform(DCT) were used to get the descriptors of lip contours in the asymmetrical lip contour model. Then the Hidden Markov Model (HMM) was trained using two kinds of descriptors as the eigenvectors of lip contours. The experiments based on isolated Chinese words show that the number of DCT descriptors needed is 15, while the number of DFT descriptors is 20 at the same recognition rate of 40%. Experiments also show that the computing quantity and the consuming time are reduced obviously by the DCT at the same recognition rate.Keywords：asymmetrical model;lip contour;boundary feature;Fourier descriptor;discrete cosine transform descriptor;Hidden Markov Model- 44
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Published：2020-08-12 -
Global calibration of CCD cameras in measurement system for 3-D foot shapes
Abstract：A measurement system for 3-D foot shapes under different loads and the practical global calibration principle of CCD cameras based on coordinate mapping and POWEL optimization method were described. The model of the measurement system was constructed based on four coordinate systems,the visual point-net grid in light plane and in CCD camera image planes was formed through the scanning of two inclined planes and the mapping relations were constructed. Finally, the objective function based on transform coefficients between different coordinate systems was defined and the transform parameters were optimized by POWEL method. Measurement results show that the repetitive error of single CCD camera is 0.062 5% and the relative measuring error of four CCDs is 0.365%. Experimental results prove that the simple and practical global calibration method can be used in the spot calibration of the measurement system, and installation errors and nonlinearity of CCD cameras can be reduced.Keywords：3-D measurement;foot shape;global calibration;coordinate mapping;nonlinear optimization- 50
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Published：2020-08-12 -
Fusion of remote sensing images based on the second generation Curvelet transform
Abstract：A novel fusion algorithm for remote sensing image based on the second generation Curvelet transform is proposed. The histogram matching between the Pan image with high spatial resolution and the band image to be fused in the Ms images is performed to eliminate the spectral differences,and the histogram matched Pan image and the band image to be fused in the Ms images are decomposed by the Curvelet transform. Then, some fusion rules are employed to obtain the Curvelet coefficients of the fused image. Finally, the inverse Curvelet transform is performed to obtain the fused Ms image with high spatial resolution. Using the proposed method to simulate several sets of IKONOS images, experimental results demonstrate that the total spectrum preservation is improved by 10.54% compared with the Intensity-hue-saturation (IHS) transform method and the spatial quality is improved by 0.81%~1.12% compared with the Discrete Wavelet Transform (DWT) method. The proposed algorithm also can overcome the high spectrum distortion of the IHS method and the low spatial quality of the DWT method, so that the proposed algorithm can not only improve the spatial quality of the fused Ms images effectively, but also make the fused images in little spectrum distortion.Keywords：image fusion;second generation Curvelet transform;Multispectral image;panchromatic image- 45
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Published：2020-08-12 -
Denoising algorithm of displacement estimation based on phase difference of Fourier transform
Abstract：A robust denoising algorithm for estimating the displacement of a moving target based on the phase difference of Fourier transform phase spectrum is presented. According to shift theorem of Fourier transform, the algorithm employs the phase spectrum difference in polar coordinates of the sequence of two frame images of a moving target to search displacement through detecting the period of the phase spectrum difference or computing the slope of its section. The vectorial filtering is used to reduce noise and keep the period characteristic, and the sectional fitting is used to compute the displacement of the slope. The experimental results show that the algorithm can give the displacement of moving target with the accuracy of 1 pixel.Keywords：Fourier transform;phase spectrum difference;displacement estimation;vectorial filtering- 37
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Published：2020-08-12 -
An illumination-independent edge detection and fuzzy enhancement algorithm based on wavelet transform
Abstract：An illumination-independent edge detection and fuzzy enhancement algorithm based on wavelet transform is proposed to extract edges out of a non-uniform weak illumination image. By educing the image wavelet transform formula from the image formation model and CCD camera imaging formula, the pixels’ wavelet module coefficients in the edge area of the image are analyzed and compared, and an illumination-independent wavelet edge detection formula insensitive to illumination is designed. Then, the fuzzy enhancement operator is proposed,which increases the difference between the edges,backgroud and noise by taking into account the wavelet module magnitude and gradient direction.Finally,through the synthetic and real images experiments, the performance of proposed edge detection method is evaluated. It is concluded that the edge detection evaluation criterion F of the proposed method for step edge is 0.984 3, the location accuracy Ed is 0.126 5, and the mean error of the cross ratio computed by the detected feature circles edge is 3.72×10-3. The experimental results prove that this edge detection method works well for the non-uniform weak illumination images.Keywords：edge detection;wavelet transform;illumination-independent;fuzzy enhancement- 49
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Published：2020-08-12 -
Modified high definition reconstruction algorithm of astronomical speckle images
Abstract：Because of atmospheric turbulence, the performance of high resolution imaging of large optical instruments is severely limited. Speckle imaging is one of ways to eliminate atmospheric blur based on recording series of images with short exposure to freeze the turbulence to obtain restoration image for reconstruction. By incorporating dynamic shrinkage of support region, a modified maximum likelihood blind deconvolution algorithm is proposed in this paper. The algorithm is applied to the restorations of short-exposure images of astronomical point source star, images of astronomical extended object and adaptive optics long exposure images of point source star. Experimental results prove that this algorithm works well not only for short exposure images of point source star, but also for images of astronomical extended object and adaptive optics long exposure images. The PSNR of reconstruction images is raised by over 10 percent. The novelty of this algorithm is that the support region of astronomical object can be contracted adaptively according to the threshold in reconstruction iterations.Keywords：astronomical image;high definition reconstruction;maximum posterior estimation;dynamic support constraint- 38
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Published：2020-08-12
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