Contents
2011
Volume: 31 Issue 8
51 Article(s)
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Atmospheric Optics and Oceanic Optics
2D Lateral Shearing Wave-Front Reconstruction Based on Decoupling Difference Zernike Future Defining Coefficient Method
Peng Aihua, Ye Hongwei, and Li Xinyang
Lateral shearing interferometry is a reference-free technique. The wavefront under test interferes with a laterally sheared copy of itself in the superposed range. The wave-front difference of the two sheared wavefronts is obtained from interferogram, the wavefront could be reconstructed using some wavefront reconstrucLateral shearing interferometry is a reference-free technique. The wavefront under test interferes with a laterally sheared copy of itself in the superposed range. The wave-front difference of the two sheared wavefronts is obtained from interferogram, the wavefront could be reconstructed using some wavefront reconstruction algorithm. The Zernike underdetermined coefficient method based on difference Zernike polynomial is one of the wavefront reconstruction algorithms. The measuring principle of lateral shearing interferometry is introduced; 2D shearing wavefront reconstruction based on decoupling difference Zernike under determined coefficient method is proposed. It is indicated by theoretical analysis and numerical simulation that the proposed method is simple, accurate and could be used to recover annular wavefront with Zernike polynomials in rectangular coordinates..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 801001 (2011)
Detectors
Study on Phase Diversity Wavefront Sensor
Li Fei, and Rao Changhui
With the improvement of the algorithms and hardware, phase diversity wavefront sensing technology becomes an important developing direction of the wavefront sensing technology, which is attributed to many advantages such as simple configuration, common path detection and so on. Phase diversity wavefront sensor is simulWith the improvement of the algorithms and hardware, phase diversity wavefront sensing technology becomes an important developing direction of the wavefront sensing technology, which is attributed to many advantages such as simple configuration, common path detection and so on. Phase diversity wavefront sensor is simulated not only for point sources but also for extended sources. An experimental testbed is built based on point source to detect the static Zernike aberration. Numerical simulations and experimental results demonstrate that phase diversity wavefront sensing technology can retrieve the wavefront accurately. Under the given experimental condition, the root mean square of the residual aberration is about λ/100 for the low order aberrations and less than λ/50 for the random aberrations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 804001 (2011)
Poisson Noise Removal for X-Ray Pulsar Integrated Pulse Profile
Hu Huijun, Zhao Baosheng, Sheng Lizhi, Yan Qiurong, Yang Hao, and Chen Baomei
The photon detection model of X-ray pulsar and the construction of pulsar integrated pulse profile are discussed. The characteristics of pulse profile which is reconstructed by the way of photon counting are analyzed. A de-noising algorithm based on non-normalized Haar wavelet is proposed, and the optimal parameters foThe photon detection model of X-ray pulsar and the construction of pulsar integrated pulse profile are discussed. The characteristics of pulse profile which is reconstructed by the way of photon counting are analyzed. A de-noising algorithm based on non-normalized Haar wavelet is proposed, and the optimal parameters for wavelet threshold function are derived based on Haar wavelet. The experimental study is done in the ground simulated experimental system for X-ray pulsar navigation. Experimental results show that the peak signal-to-noise ratio can be improved by at least 2 dB, and the accuracy of time-of-arrival (TOA) measurement is also improved, which is proved by Monte Carlo simulation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 804002 (2011)
Diffraction and Gratings
Moiré Fringe-Based Focusing-Test Scheme for Optical Projection Lithography
Yan Wei, Li Yanli, Chen Mingyong, and Wang Jian
Based on the short wavelength, large numical operture, and short focal depth of optical projection lithography, a focusing method is presented based on Moiré fringe and the principle of triangulation. By analyzing the optical properties of photoelastic modulation and Savart plate, combining the intensity modulatioBased on the short wavelength, large numical operture, and short focal depth of optical projection lithography, a focusing method is presented based on Moiré fringe and the principle of triangulation. By analyzing the optical properties of photoelastic modulation and Savart plate, combining the intensity modulation mechanism of dual-grating Moiré fringes, the linear relation between focal plane displacement and output light energy is established in a single grating period. After theoretical analysis and simulated test, it shows precision at nanometer scale with the property of non-contacting, high robustness and well time efficiency, meeting the demands of focusing test in projection lithography..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 805001 (2011)
Fiber Optics and Optical Communications
Cascaded All-Fiber 1020 nm Light Source Based on Fiber Raman Amplification
Xu Jiangming, Leng Jinyong, Hou Jing, Wu Wuming, Xiao Hu, and Zhou Pu
Cascaded all-fiber 1020 nm light source with 196 mW output power is designed and demonstrated. This light source can realize the amplification of low-power 1020 nm seed light with a cascaded amplifier. The cascaded amplifier is composed of fiber Raman amplifier and Yb3+-doped single-mode fiber amplifiers. At the stage Cascaded all-fiber 1020 nm light source with 196 mW output power is designed and demonstrated. This light source can realize the amplification of low-power 1020 nm seed light with a cascaded amplifier. The cascaded amplifier is composed of fiber Raman amplifier and Yb3+-doped single-mode fiber amplifiers. At the stage of fiber Raman amplification, comparing experiments with three different Raman gain fiber lengths are performed to study the influence of fiber length on the output power at fixed seed power and pump power, and the spectrum of output light with 3150 m Raman gain fiber is measured. The spectrum and power characteristics of output light of Yb3+-doped single-mode fiber amplifiers are studied. This 1020 nm light source provides pump source for the study of the tandem pumping of 1064 nm fiber laser. And this cascaded all-fiber amplification solution based on fiber Raman amplification can be used to amplify other special seed light at low power..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806001 (2011)
Optimization of Phase Noise of Opto-Electronic Oscillator Through Low-Biasing Technology for Modulator
Hong Jun, Yang Chun, Chong Yuhua, and Li Xianghua
A novel method for reducing the phase noise of the opto-electronic oscillator (OEO) is proposed and experimentally demonstrated. As for a given single-loop OEO, its phase noise characteristics are determined by the noise-to-signal ratio (NSR) which can be reduced by optimizing the direct current (DC) bias voltage of thA novel method for reducing the phase noise of the opto-electronic oscillator (OEO) is proposed and experimentally demonstrated. As for a given single-loop OEO, its phase noise characteristics are determined by the noise-to-signal ratio (NSR) which can be reduced by optimizing the direct current (DC) bias voltage of the modulator. Results show that, when the injected optical power equals to 60 mW, the minimum single sideband (SSB) phase noise at the low bias point is gotten which decreases by 2.8 dB than that at the quadrature bias point of the electro-optic modulator..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806002 (2011)
A Novel Single-Polarization Single-Mode Photonic Crystal Fiber with Two Arrays of Four Lines of Semiminor-Axis-Decreasing Elliptical Air-Holes
Zheng Hongjun, Wu Chongqing, Wang Jian, Wang Zhi, Liu Shanliang, and Li Xin
A novel single-polarization single-mode photonic crystal fiber (SPSM-PCF) design with two arrays of four lines of semiminor-axis-decreasing elliptical air-holes is proposed. The proposed SPSM-PCF characteristics are investigated by using a full-vector finite element method (FEM) with perfect matched layer (PML) boundarA novel single-polarization single-mode photonic crystal fiber (SPSM-PCF) design with two arrays of four lines of semiminor-axis-decreasing elliptical air-holes is proposed. The proposed SPSM-PCF characteristics are investigated by using a full-vector finite element method (FEM) with perfect matched layer (PML) boundary conditions. The modal birefringence of the proposed SPSM-PCF is as high as 2.752×10-3 at the wavelength of 1.550 μm and the beat length is 0.564 mm. The confinement loss of the x-polarization mode is as low as 0.139 dB/km, whereas the loss of the y-polarization mode is as large as 16.890 dB/km. Compared with the case of x-polarization mode, the y-polarization mode can be suppressed with a shorter fiber length. The numerical aperture is 0.415, the effective mode-field area is 3.667 μm2, and the nonlinear coefficient is 28.740 (W·km)-1 at the wavelength of 1.550 μm. The total dispersion profile of the SPSM-PCF is dispersion-flattened with the wavelength range from 1.347 to 1.691 μm. This dispersion property makes the proposed SPSM-PCF useful for various applications such as supercontinuum spectrum generation and pulse transmission. The spectral region of input light for SPSM operation is as wide as 600 nm. It indicates that this is a good solution to realize broadband dispersion-flattened SPSM operation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806003 (2011)
Bit Interleaved Product Coded Pulse Position Modulation with Iterative Demodulation for Free-Space Optical Communication
Hu Hao, Wang Hongxing, Xu Jianwu, Sun Xiaoming, and Liu Min
There is a poor efficiency for pulse position modulation (PPM) in combination with binary correction coding for free space optical communication. To solve the problem, a new scheme, which introduces bit interleaving and iteration technology into product coded PPM, is proposed. Bit interleaver is used to make signal decThere is a poor efficiency for pulse position modulation (PPM) in combination with binary correction coding for free space optical communication. To solve the problem, a new scheme, which introduces bit interleaving and iteration technology into product coded PPM, is proposed. Bit interleaver is used to make signal decline independently. Soft demodulation method of PPM is derived under weak turbulence and Gaussian cascaded channel based on maximum-likelihood criterion. Combined with soft input soft output (SISO) algorithm of block decoding, iteration between demodulation and decoding is achieved. Simulations under weak turbulence show that, the scheme provides 1 dB gain at bit errror rate (BER) of 10-5 compared with bit interleaved product coded PPM with independent demodulation and decoding, and has perfect error performance at high code rate, which is valuable in high reliability in information transmission with comparatively lower bandwidth requirement. The proposed scheme provides a solution to efficiently unite error control coding with PPM in atmospheric optical wireless communication systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806004 (2011)
A Novel Fiber Sagnac Magnetic Field Sensor Based on Magnetic Fluid
Zu Peng, Xiang Wanghua, Bai Yangbo, and Jin Yongxing
An optical fiber Sagnac magnetic field sensor based on magnetic fluid is proposed. The magnetic fluid exhibits magneto-optic birefringence under external magnetic field, in which the nanoparticles form chains along the magnetic field and cause the anisotropy. The interference spectrum of the sensor shifts with the exteAn optical fiber Sagnac magnetic field sensor based on magnetic fluid is proposed. The magnetic fluid exhibits magneto-optic birefringence under external magnetic field, in which the nanoparticles form chains along the magnetic field and cause the anisotropy. The interference spectrum of the sensor shifts with the external magnetic field due to the magnetic fluid film inserted in the Sagnac loop together with a section of polarization maintaining fiber. The output spectrum shifts with the variation of magnetic field strength when the plane of the magnetic fluid is perpendicular to the direction of the light and parallel to the direction of the external magnetic field. The achieved sensitivity and resolution of the sensor, which are related to the thickness of the magnetic film, are 16.7 pm/Oe (1 Oe≈79.578 A/m) and 0.60 Oe for 60 μm thickness, respectively. When the plane of the magnetic fluid is perpendicular to the direction of the magnetic field, the output spectrum does not shift with the variation of the magnetic field strength..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806005 (2011)
Study on Spectral Properties of Tilted Long-Period Fiber Grating Written by High-Frequency CO2 Laser Pulses
Wei Shilei, Zhang Weigang, Fan Hongjian, Geng Pengcheng, Shang Jiabin, Yin Limei, and Xue Xiaolin
A novel tilted long-period fiber grating (TLPFG) written by high-frequency CO2 laser pulses was experimentally demonstrated. The coupled-mode theory was modified in order to theoretically analyze the TLPFG. The effects of tilted refractive index modulation on the spectral properties of the TLPFG were studied. The influA novel tilted long-period fiber grating (TLPFG) written by high-frequency CO2 laser pulses was experimentally demonstrated. The coupled-mode theory was modified in order to theoretically analyze the TLPFG. The effects of tilted refractive index modulation on the spectral properties of the TLPFG were studied. The influence of tilted angle on the modes coupling of TLPFG was analyzed. Theoretical analysis is in accord with experimental results. The experimental results show that the TLPFG written by high-frequency CO2 laser pulses has many novel properties. The coupling coefficient of low-order cladding modes is higher than that of high-order ones, and tilted refractive index modulation not only can enhance the coupling coefficient between the core fundamental mode and cladding modes, but also can stimulate the coupling between core fundamental and high-order cladding modes. The written efficiency can be dramatically improved by increasing the tilt angle..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806006 (2011)
Investigation on Phase Spectra of Fiber Bragg Gratings and the Constructed Fabry-Pérot Cavity
Niu Siliang, Rao Wei, Jiang Nuan, and Hu Yongming
Phase spectrum of fiber Bragg grating (FBG) has a major effect on spectral characteristics of the constructed Fabry-Pérot (F-P) cavity. By the analysis of spectral characteristics of an FBG, especially its phase spectrum, the linear phase spectrum of a weak grating is derived. Furthermore, the three-segment linearPhase spectrum of fiber Bragg grating (FBG) has a major effect on spectral characteristics of the constructed Fabry-Pérot (F-P) cavity. By the analysis of spectral characteristics of an FBG, especially its phase spectrum, the linear phase spectrum of a weak grating is derived. Furthermore, the three-segment linear approximation is proposed for strong gratings with a concise expression. Then, based on the deduced analytic expressions of phase spectra, spectral characteristics of FBG based Fabry-Pérot (FBG-FP) cavities are investigated by the conception of effective cavity in comparison with general F-P cavities. The fitting method, periodic method and Fourier transform method for FBG-FP cavity length estimation are discussed. A scheme of spectral measurement of FBG-FP cavities is designed, which obtains spectral curves with a high accuracy. The above three methods for cavity length estimation are compared mutually with tested spectra, and theoretical analyses are validated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806007 (2011)
Study of Novel Fabrication Process for Non-Zero Dispersion-Shifted Fibers
Wu Jindong, Li Qingguo, Wu Wenwen, Sun Keyuan, Chen Haibin, Li Qiang, and Wu Xingkun
A novel preform fabrication process for non-zero dispersion-shifted fibers using hybrid modified chemical vapor deposition (MCVD)+ vapor axial deposition (VAD) technique is presented. The new design concept of the hybrid process is based on the normalized waveguide structure of the fiber, whereby fabricating core prefoA novel preform fabrication process for non-zero dispersion-shifted fibers using hybrid modified chemical vapor deposition (MCVD)+ vapor axial deposition (VAD) technique is presented. The new design concept of the hybrid process is based on the normalized waveguide structure of the fiber, whereby fabricating core preforms with homogeneous normalized waveguide using MCVD process and out-cladding using axis control technique via VAD process to realize a homogeneous waveguide along axis of the preform. The manufacturing process of non-zero dispersion-shifted fibers is experimentally studied and the results show that preforms with homogeneous waveguide are fabricated successfully, with effective use of the taper of the preforms to increase the preform length, achieving about 15% increase of fiber production efficiency and cost reduction. Three key procedures in the hybrid fabrication process are discussed in detail, including the fabrication of normalized structure, the initialization of constriction ratio of core preform and the soot deposition via VAD process. The results provide a useful guideline for practical fabrication of non-zero dispersion-shifted fibers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806008 (2011)
Long Period Fiber Grating Refractive Index Sensitivity-Based Reinforcing Rebar Corrosion Sensor in Concrete
Liu Hongyue, Liang Dakai, Zeng Jie, Jin Jing, Wu Jin, and Geng Jiang
The principle of a long-period fiber grating (LPFG) rebar corrosion sensor is discussed in detail firstly based on a sensitive characteristic that the resonance spectrum of LPFG changes with refractive index in external environment. The theory combining the refractive index around rebar in concrete and the resonance spThe principle of a long-period fiber grating (LPFG) rebar corrosion sensor is discussed in detail firstly based on a sensitive characteristic that the resonance spectrum of LPFG changes with refractive index in external environment. The theory combining the refractive index around rebar in concrete and the resonance spectrum is proposed. Then, LPFG spectrum measurement technology is selected to obtain LPFG spectrum curves corresponding with different kinds of refractive index in concrete, and the relationship between the resonance peak wavelength and the state of rebar corrosion in concrete is obtained. The experimental results numerically show that the resonance peak wavelengths increase and then decrease with the increasing corrosion rates. This method which can directly monitor the state of rebar corrosion in concrete is simple and easy to operate. The measurement and transmission sections of the system are completely composed of optical fiber, which can avoid the electronic interference. There is no necessity to use chemical reagent to sign the solutions which are going to be degraded. In conclusion, the late-model LPFG rebar corrosion monitoring system can achieve a real time, rapid, accurate and long distance measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806009 (2011)
Numerical Simulation and Analysis of Double Cladding Photonic Crystal Fiber with Flattened Dispersion
Wang Dan, and Zheng Yi
Dispersion of fiber may broaden the pulse width and lead to error, which must be avoided in optical communications. Using the finite element method (FEM) and considering the material dispersion of SiO2, the mode field, the effective index of fundamental mode and the dispersion property of double-cladding photonic crystDispersion of fiber may broaden the pulse width and lead to error, which must be avoided in optical communications. Using the finite element method (FEM) and considering the material dispersion of SiO2, the mode field, the effective index of fundamental mode and the dispersion property of double-cladding photonic crystal fiber (PCF) with circular arrangement are numerically simulated. Results show that the distance between large air holes and small air holes of the first layer and the diameter of large air holes determine the shape of dispersion curve when the distance and diameter of small air holes are unchanged. As some dispersion-compensating fiber, the effctive mode refractive index has a transition at a wavelength,thus flattened dispersion can be realized. For example, when diameter d1=3.1 μm, d2=1 μm, distance Λ1=5 μm and Λ2=4 μm, within the wavelength range of 1.22~1.6 μm, the difference between the maximun and minimum of dispersion is less than 4 ps/(nm·km)..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806010 (2011)
Analysis on Upper Limit of Dynamic Range of Fiber Optic Interferometric Hydrophone Using Digital Heterodyne Detection Scheme
Zhang Nan, Meng Zhou, Rao Wei, and Xiong Shuidong
The principle of fiber optic interferometric hydrophone using heterodyne detection scheme is introduced and the upper limit of dynamic range of the digital heterodyne detection is analyzed in detail. The upper limits of dynamic range decided by heterodyne frequency and the arctangent or differential cross-multiply (DCMThe principle of fiber optic interferometric hydrophone using heterodyne detection scheme is introduced and the upper limit of dynamic range of the digital heterodyne detection is analyzed in detail. The upper limits of dynamic range decided by heterodyne frequency and the arctangent or differential cross-multiply (DCM) quadrant demodulation algorithm are analyzed in theory and compared with each other. Analysis results indicate that the upper limit of dynamic range changes with heterodyne frequency. However, with the same heterodyne frequency, different upper limits of dynamic range are achieved with arctangent or DCM algorithm. The upper limit of dynamic range can achieve a higher value when the heterodyne frequency is equal to a quarter of the sampling rate and the arctangent quadrant demodulation algorithm is adopted. Numerical simulation validates the theoretical analysis. A fiber optic hydrophone system based on heterodyne detection technique is constructed and the experimental results, which correspond to the theoretical results, demonstrate the feasibility of the fiber optic hydrophone to achieve large dynamic range and large-scale array..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 806011 (2011)
Geometric Optics
Concentration Ratio Analysis of Linear Fresnel Reflector
Du Chunxu, Wang Pu, Wu Yuting, and Ma Chongfang
It is necessary to analyze the concentration ratio for the design of concentrating solar thermal power system. Linear Fresnel reflector (LFR) can be treated as a smooth linear optical reflector that is broken into segments. Every mirror segment or row of this kind of concentrator needs to track the sun in real time andIt is necessary to analyze the concentration ratio for the design of concentrating solar thermal power system. Linear Fresnel reflector (LFR) can be treated as a smooth linear optical reflector that is broken into segments. Every mirror segment or row of this kind of concentrator needs to track the sun in real time and reflects the sunlight to a fixed linear receiver. Therefore, the bandwidth on the absorber illuminated by every mirror row varies continuously, which makes the analysis of concentration ratio very complex. Firstly, the formulae for the projected angles of incident and reflected solar rays, the tracking inclination angle and the bandwidth illuminated on the flat plane absorber are obtained by a two-dimensional optic analysis. Secondly, the expressions of geometric concentration ratio of LFR are derived and the dependence of ideal geometric concentration ratio on number of mirror slats and relative distance is analyzed. And then, optimization of mirror field width and tower height is analyzed. Finally, the effect of angular size of the sun′s disc on geometric concentration ratio is illuminated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 808001 (2011)
Imaging Systems
Compressive Double-Lens Imaging Using Circulant-Toeplitz-Block Phase Mask
Zhang Cheng, Yang Hairong, and Wei Sui
Compressive imaging is an important application of the theory of compressive sensing, which can capture sufficient information of sparse/compressible image for reconstruction with fewer measurements than Nyquist samples. Taking advantage of the existing compressive imaging methods, a novel methodcompressive double-lensCompressive imaging is an important application of the theory of compressive sensing, which can capture sufficient information of sparse/compressible image for reconstruction with fewer measurements than Nyquist samples. Taking advantage of the existing compressive imaging methods, a novel methodcompressive double-lens imaging using circulant-Toeplitz-block phase mask is proposed. Simulation results show that the novel phase mask matrices imaging method can effectively capture the information of image for image reconstruction with subsamples. The research of new imaging method provides more supports for deterministic measurement in the application of compressive imaging, which, due to its specific structure, has more advantages than Toeplitz and circulant matrices, and reduces the difficulty and costs of the physical realization..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 811001 (2011)
Instrumentation, Measurement and Metrology
Phase Retardation Measurement with Least Square Fitting Method
Hou Junfeng, Wang Dongguang, Deng Yuanyong, Zhang Zhiyong, and Sun Yingzi
A new method for measuring the retardation of waveplates with high precision is brought forward. The measured waveplate is placed between polarizer and analyzer, and rotates uniformly under the control of stepper motor. The phase retardation can be calculated with the least square method fitting the curve of emergent lA new method for measuring the retardation of waveplates with high precision is brought forward. The measured waveplate is placed between polarizer and analyzer, and rotates uniformly under the control of stepper motor. The phase retardation can be calculated with the least square method fitting the curve of emergent light intensity variation with the azimuth angle of waveplate. Based on the analysis, an experimental system is established to measure the retardation. Four parts, including stability of the system, retardation range for measuring, nonlinearity of the detector, the main error sources of the system are analyzed. It is found that λ/2 waveplate cannot be measured in this system; higher stability can be obtained when the azimuth angle of analyzer ranges from -38° to 38° and the sampling interval is less than 10°; the detector has large second-order nonlinear effect; the measurement precision is mainly affected by the uncertainty of azimuth angle of waveplate and analyzer; repeatability of the system is within 0.1° except for the areas near 0\O, 180° and 360°. The measurement precision of the system is almost constant in visible range..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812001 (2011)
Analysis of Effect of Tiny Pinhole Deviation on Far-Field Wave-Front Quality
Lu Zengxiong, Jin Chunshui, Ma Dongmei, and Zhang Haitao
The quality of the reference wave front in point-diffraction interferometer (PDI) is constrained by the quality of the pinhole, and the deviation between an actual pinhole and a perfect one is caused by machining errors and the misalignment. The quality of the far-field wave front diffracted by a rough-edge circular piThe quality of the reference wave front in point-diffraction interferometer (PDI) is constrained by the quality of the pinhole, and the deviation between an actual pinhole and a perfect one is caused by machining errors and the misalignment. The quality of the far-field wave front diffracted by a rough-edge circular pinhole and an elliptical pinhole is analyzed in detail based on Rayleigh-Sommerfeld diffraction formula. Pinhole edge roughness mainly causes the trefoil aberration in diffracted wave front, and the ellipticity of a pinhole will lead to a small amount of astigmatism in diffracted wave front. For pinholes with diameters from 0.4 to 1.0 μm, when the radius root mean square (RMS) deviations are 0, 15 and 30 nm, the RMS deviations of the diffracted wave fronts are in the order of 10-8λ, 10-4λ and 10-3λ, respectively. The results show that pinhole edge roughness has a significant influence on wave front deviation, while it has little to do with the intensity distribution in the diffracted wave front. The ellipticity of the pinhole has very small effect on wave front deviation, but affects the wave front intensity distribution in far-field wave front. Usually, the ellipticity of an elliptical pinhole resulting from machining errors or the misalignment is small, and its effect on far-field wave front quality can be neglected..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812002 (2011)
Feature Patch-Based Vision Measuring Technique for Complex Surface and Silhouette
Li Jinjun, and Zhao Hong
A feature patch-based three-dimensional vision measuring technique for complex surface and silhouette is proposed. There are several procedures for the proposed method including detecting and matching multi-modal local features, initializing, expanding and filtering patch sets. The algorithm outputs a dense set of rectA feature patch-based three-dimensional vision measuring technique for complex surface and silhouette is proposed. There are several procedures for the proposed method including detecting and matching multi-modal local features, initializing, expanding and filtering patch sets. The algorithm outputs a dense set of rectangular patches covering the surfaces visible in the input calibrated images. The first step of the proposed algorithm is implemented as a matching, expanding, and filtering procedure. It starts from a sparse set of matched key points, and repeatedly expands these to nearby pixel correspondences using the monogenic feature congruency and the epipolar geometric constraint before using visibility constraints to filter away false matches. The keys to its performance are effective techniques for enforcing local photometric consistency and global visibility constraints. A simple but effective polygonal surface extraction algorithm is then used to turn the resulting patch model into a mesh appropriate for image-based modeling. According to the multi-modal monogenic features of a patch, the color and texture information is fused into the reconstructed mesh. Thus a three-dimensional high-fidelity solid model can be obtained finally..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812003 (2011)
Rotating Chuck Test for Removing Chuck Error of Optical Surface
Wang Ping, Tian Wei, Wang Rudong, Wang Lipeng, Sui Yongxin, and Yang Huaijiang
In order to realize high accuracy test for optical surface, a rotation chuck method is built and its principle, model analysis and error analysis are researched. Based on the optical component mounting case, the property of surface deformation is analyzed. The surface profile is fitted with Zernike polynomials. The priIn order to realize high accuracy test for optical surface, a rotation chuck method is built and its principle, model analysis and error analysis are researched. Based on the optical component mounting case, the property of surface deformation is analyzed. The surface profile is fitted with Zernike polynomials. The principle model of rotation chuck method is studied, and the equation of surface real profile is derived from the model. Then, the principle model is analyzed with numerical simulation method. The results of surface profile and the real surface profile are compared. Finally, the error sources of rotation chuck method are researched. Analysis results indicate that the rotation chuck method can remove mounting error efficiently, the difference between the computed profile and the real profile is the high-order symmetrical Zernike polynomials, which can satisfy the high accuracy requirement of optical surface tests..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812004 (2011)
Phase Subdivision of Absolute Coding Grating and Application in Displacement Measurement
Zhao Yong, Su Xianyu, and Zhang Qican
A phase subdivision of absolute coding is proposed to enhance the resolution of absolute coding grating in displacement measurement . The used grating consists of multiple code channel grating. CCD image sensor acquires information of multiple code channel in measurement section. The absolute phase distribution in measA phase subdivision of absolute coding is proposed to enhance the resolution of absolute coding grating in displacement measurement . The used grating consists of multiple code channel grating. CCD image sensor acquires information of multiple code channel in measurement section. The absolute phase distribution in measurement section is obtained by Fourier transform, filtering, inverse Fourier transform, and phase unwrapping. Practical absolute coding grating is fabricated by lithography. The size of minimum code pattern is 27.36 μm for light and dark fringe. Space period of benchmark code sequence pattern is 54.72 μm, and the length of grating is 14008.32 μm. A large number of displacement tests are carried out. In the displacement test of step length approximate 3 μm, compared with the record value of standard equipment, the standard deviation is 0.2057 μm. The precision reaches sub-micron level. The stability tests demonstrate that the resolution of 600 times of subdivisions on minimum code pattern is gotten..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812005 (2011)
Algorithm for Extending Dynamic Range of Shack-Hartmann Wavefront Sensor
Zhang Jinping, Zhang Zhongyu, Zhang Xuejun, and Li Ruigang
A new algorithm called spots regression is presented to solve the tradeoff between the dynamic range and sensitivity of Shack-Hartmann wavefront sensor. This new algorithm allows spots to wander, so the dynamic range can be extended while the sensitivity is also sensitive. In order to find out the relation between the A new algorithm called spots regression is presented to solve the tradeoff between the dynamic range and sensitivity of Shack-Hartmann wavefront sensor. This new algorithm allows spots to wander, so the dynamic range can be extended while the sensitivity is also sensitive. In order to find out the relation between the spots array and microlenses array even if spots leave their original sub-aperture, firstly, getting the irregular spots to their primary positions, secondly, finding out the match relation between one spot and one microlens. Finally , all spots and all microlenses match each other. The advantage of this algorithm is that there are no requirements for extra hardware, multiple measurements or complicated algorithms. A simple experiment is carried out to demonstrate its implementation. The results of this experiment are very closed to the theoretical ones. And the dynamic range is 25 times larger than that of conventional algorithm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812006 (2011)
Evaluation of Incident Light Intensity Based on Gregory Theory of Light Fluctuation for In-Line Particle Sizing Measurement
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
For in-line measurement of particle size and concentration based on the light fluctuation method, the intensity of incident light must be pre-detected. However, it is very difficult to measure the incident light intensity during the in-line measurement because the incident light intensity is easily affected by many facFor in-line measurement of particle size and concentration based on the light fluctuation method, the intensity of incident light must be pre-detected. However, it is very difficult to measure the incident light intensity during the in-line measurement because the incident light intensity is easily affected by many factors. A novel method based on Gregory′s light fluctuation method is proposed. The relation among the intensity of incident light, the ratio of particle concentrations at different time, the standard deviation and the mean value of the intensity of transmitted light is established. With those measurable parameters the intensity of incident light may be obtained. Experimental results agree well with the pre-detected value of the intensity of incident light, and the maximum deviation is less than 1.1%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812007 (2011)
A New Adaptive Background Correction Method Based on Pinhole Image Analysis in Optical System Modulation Transfer Function Measurement
Duan Yaxuan, Chen Yongquan, Zhao Jianke, Li Kun, and Long Jiangbo
A new adaptive background correction method based on pinhole image analysis in optical system modulation transfer function (MTF) measurement is proposed. The pinhole image is got from the CCD, and the line spread function is computed from it. The MTF is got from the adaptive background correction to the line spread funA new adaptive background correction method based on pinhole image analysis in optical system modulation transfer function (MTF) measurement is proposed. The pinhole image is got from the CCD, and the line spread function is computed from it. The MTF is got from the adaptive background correction to the line spread function. Compared with the traditional background correction method, it is unrelated to the change of ambience illumination, and the measurement accuracy is improved. Standard lens and aberrated lens are tested to prove the validity of the adaptive background method. The maximum difference between the test results of standard lens and the academic results is 0.01. Compared with Optikos MTF testing results, the maximum difference is 0.015. The maximum difference between test results of aberrated lens and Optikos MTF testing results is 0.013. The test results show that the adaptive background correction method is practical to the MTF tests of most optical lenses..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812008 (2011)
Triple-Frequency Color-Encoded Fringe Projection Profilometry Based on Empirical Mode Decomposition
Zou Haihua, Zhao Hong, and Zhou Xiang
A triple-frequency color-encoded fringe projection profilometry based on empirical mode decomposition is presented to measure the dynamic objects in real time. Sinusoidal fringe patterns of three frames with different frequencies are encoded in red, green, blue (RGB) channels, respectively, projected on the objects by A triple-frequency color-encoded fringe projection profilometry based on empirical mode decomposition is presented to measure the dynamic objects in real time. Sinusoidal fringe patterns of three frames with different frequencies are encoded in red, green, blue (RGB) channels, respectively, projected on the objects by projector at the same time, and the deformed fringe patterns are captured by CCD at another angle. The background components are eliminated after subtracting the red channel′s component from both blue and green components. Then empirical mode decomposition is used for color decoupling and separating the highest, medium and lowest fundamental frequency components. Phases are demodulated by using Fourier transform, and the warpped phase demodulated from the highest fundamental frequency components is unwrapped by three-step phase unwrapping with variable precision algorithm. The simulation experiment, in which the standard deviation of phase demodulation is less than 0.0417 rad, shows the method has high precision. Furthermore, the method is verified to be effective by contrast experiments and experiment on facial expression. It implements phase demodulation and phase unwrapping with high precision based on single snapshot, thus it is very effective to measure 3D surface contour of dynamic objects with high precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812009 (2011)
A Method for Testing Radius of Curvature of Optical Spheric Surface
Wang Xiaokun, and Zheng Ligong
On the basis of summing up conventional testing methods for the radius of curvature of optical sphere, a novel method using laser tracker and interferometer is proposed. The focus of the exit spheric surface wave front and the coordinate of curvature center of the testing spheric surface are tested by a laser tracker. On the basis of summing up conventional testing methods for the radius of curvature of optical sphere, a novel method using laser tracker and interferometer is proposed. The focus of the exit spheric surface wave front and the coordinate of curvature center of the testing spheric surface are tested by a laser tracker. After adjusting the spheric surface and the interferometer, the coordinates of many points on the spheric surface are tested, and then the radius of curvature of the spheric surface can be calculated by the data. The basic principle and theory of the method are researched, and the synthetical optimization method for testing radius of convex spheric surface is proposed. An optical lens with the aperture of 400 mm is tested by the method. The radius of the convex surface is measured to be 1022.283 mm, and that of the concave surface is 4069.568 mm. For comparison and validation, the spheric surface is also tested by a profilometer, and the relative errors for both surfaces are less than 0.05%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 812010 (2011)
Integrated Optics
Analysis of Single-Mode Condition for Organic Polymer Asymmetric Ridge Waveguide
Gao Yuan, Zhang Xiaoxia, and Liao Jinkun
The fundamental mode cut-off and single-mode conditions of asymmetric ridge waveguide under different ridge heights, ridge widths and the short side widths of core plate are systematically studied in semi-vector finite-difference beam propagation method (FD-BPM) with organic polymer asymmetric ridge waveguide as the obThe fundamental mode cut-off and single-mode conditions of asymmetric ridge waveguide under different ridge heights, ridge widths and the short side widths of core plate are systematically studied in semi-vector finite-difference beam propagation method (FD-BPM) with organic polymer asymmetric ridge waveguide as the object. The result shows that both fundamental mode cut-off area and single-mode area increase with reduction of ridge height and ridge width while single-mode area decreases with reduction of short side width of core plate at a certain core height. The structure is optimized as core height h≥1.5 μm, ridge height (H-h)≤0.4 μm, ridge width 4 μm≤w≤8 μm, short side width s=2 μm. The research shows that the single-mode area of asymmetric ridge waveguide meets requirements of practical application..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 813001 (2011)
Lasers and Laser Optics
Technology and Mechanism of CO2 Laser Treatment for Mitigating Surface Damage Growth
Hu Guohang, Zhao Yuan′an, and Li Dawei
Growth of laser induced damage on the surface of fused silica plays a major role in determining optics lifetime in high power laser systems. CO2 laser is used to mitigate the damaged spot. It locally meltes and evaporates the fused silica surface, producing smooth, Gaussian shaped pit, eliminating the cracks and rough,Growth of laser induced damage on the surface of fused silica plays a major role in determining optics lifetime in high power laser systems. CO2 laser is used to mitigate the damaged spot. It locally meltes and evaporates the fused silica surface, producing smooth, Gaussian shaped pit, eliminating the cracks and rough, uneven on surface. Moreover, the damage threshold of mitigation spot is much higher than the damage growth threshold of fused silica. So CO2 laser mitigation treatment can successfully inhibit the growth of laser-induced surface damage on fused silica. The temperature distribution on the surface of fused silica induced by a CO2 Gaussian beam has been discussed to analyze the formative process of Gaussian shaped pits and determine the best mitigation parameter. Atomic force microscopy (AFM) and profiler are applied to observe the micro-structure of damage and mitigation spots. Finite-difference time-domain (FDTD) method is applied to calculate the light intensity distribution around the mitigation and damage spots. They provide useful information to understand the mitigation mechanisms..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 814001 (2011)
Reflectance of Epoxy/Organsilicone Composite Coating at 1.3 μm under Laser Irradiation
Wu Lixiong, Ye Xisheng, Wang Lijun, Wu Yaojun, Liu Weiping, and Liu Zejin
Experimental research on 1.3 μm reflectance of epoxy/organsilicone two-layer composite coating under infrared continuous-wave (CW) laser irradiation in vacuum is carried out. An experimental system for laser irradiation and reflectance measurement is set up with conjugated reflectometer. Results of signal detection theExperimental research on 1.3 μm reflectance of epoxy/organsilicone two-layer composite coating under infrared continuous-wave (CW) laser irradiation in vacuum is carried out. An experimental system for laser irradiation and reflectance measurement is set up with conjugated reflectometer. Results of signal detection theory (SDT) analysis indicate that heat deposition generated by laser makes pyrogenation of epoxy primer which leads to form and burst of bubbles and thermal ablation of topcoat. Heat transfer within coating-metal structure is simulated by finite element analysis procedure with interface thermal resistance modification, and the temperature-dependent reflectance is presented. Investigation results show that the change of reflectance is related to the modes of damage and processes of decomposition. 1.3 μm reflectance of epoxy/organsilicone coating is about 0.80 at room temperature, changes slightly at the very beginning of laser irradiation, decreases remarkably while bubbles burst and thermal ablation occurrs, and finally maintains a rather low level. There are three characteristic temperatures of reflectance evolution, the decomposition temperature of epoxy primer, the decomposition temperature of organosilicone topcoat, and the decomposition temperature when the reaction ends and the surface tends to be steady..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 814002 (2011)
Study on Time Instability of Pulsed Light Field from Q-Switched Intracavity Frequency-Doubled Laser
Xu Xin, Wang Shiyu, Cai Defang, Li Bingbin, Guo Zhen, and Wen Jianguo
Based on the principle of Q-switched intracavity frequency doubled laser, the shape of the second harmonic pulse and the second harmonic unstable light field distribution under the various forms of pump light distribution are studied, and the variation of the second harmonic beam quality is also analyzed. It is found tBased on the principle of Q-switched intracavity frequency doubled laser, the shape of the second harmonic pulse and the second harmonic unstable light field distribution under the various forms of pump light distribution are studied, and the variation of the second harmonic beam quality is also analyzed. It is found that the light field of Q-switched intracavity frequency-doubled laser is changing in the duration of pulse. In the case of Gaussian type of pump light, it is found that the instability will decrease when the cavity length decreases. And the instability increases by increasing the ratio of the pump light radius and that of the oscillating light, but the average beam quality factor M2 will be greater..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 814003 (2011)
629 nm He-Ne Laser Using Built-in Fabry-Perot Etalon
Nie Xiaoming, Long Xingwu, Zhang Bin, and Liang Jing
629 nm spectral line can be obtained with the method using Fabry-Perot (F-P) etalon in He-Ne laser cavity. That spectral line is hard to realize by the traditional method, like coating film. The shifting of 629 nm line′s transmission window in F-P etalon is analyzed. In order to obtain a stable 629 nm output, the lower629 nm spectral line can be obtained with the method using Fabry-Perot (F-P) etalon in He-Ne laser cavity. That spectral line is hard to realize by the traditional method, like coating film. The shifting of 629 nm line′s transmission window in F-P etalon is analyzed. In order to obtain a stable 629 nm output, the lower limit of the F-P etalon′s angle range is calculated. A new folding piezoelectric angle controller is presented, which can provide a wide angle range adjustment. A stable output 629 nm He-Ne laser is realized with a feedback control. The stable output light power reaches 80 μW approximately..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 814004 (2011)
Lamb-Dip Frequency-Stabilized He-Ne Laser With an Integrated Cavity Made of Zerodur (Ⅰ): Structure and Techniques
Zhang Bin, Long Xingwu, Liu Jianping, Zhao Hongchang, and Liu Jun
The basic structure of traditional Lamb-dip stabilized He-Ne laser and its cavity length controlling manner are introduced. The influence of the laser′s structure on its warm-up time, frequency stability and reproducibility is discussed in detail. The basic structure and techniques of a novel-type integrated Lamb-dip sThe basic structure of traditional Lamb-dip stabilized He-Ne laser and its cavity length controlling manner are introduced. The influence of the laser′s structure on its warm-up time, frequency stability and reproducibility is discussed in detail. The basic structure and techniques of a novel-type integrated Lamb-dip stabilized He-Ne laser are presented, whose cavity with very low coefficient of expansion is made of zerodur. There are noticeable techniques applied in the laser, including the quartz reflective mirrors′ optical contact and the super high vacuum indium seal, that ensure the cavity′s steady operation and its frequency high stability. The experimental result shows that the laser is able to operate well without warm-up time, even though in the condition of either high-low temperature or shocking environment, whose relative frequency stability can reach the order of magnitude of 10-10..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 814005 (2011)
Tunable Erbium-Doped Fiber Laser Based on Multi-Mode Fiber Filter
Hao Yanping, Zhang Shumin, Wang Xinzhan, Meng Yichang, Li Huihui, Du Juan, and Li Hongfei
A new-style, all-fiber, broad-band tunable erbium-doped fiber ring laser is proposed. The wavelength continuous tuning is realized by using a single-mode/multimode/single-mode fiber as a filter, in which the multimode fiber is wrapped around a polarization controller, and is spliced to a single-mode fiber at each ends.A new-style, all-fiber, broad-band tunable erbium-doped fiber ring laser is proposed. The wavelength continuous tuning is realized by using a single-mode/multimode/single-mode fiber as a filter, in which the multimode fiber is wrapped around a polarization controller, and is spliced to a single-mode fiber at each ends. By carefully adjusting the polarization controllers in the cavity, the output central wavelength of tunable single-wavelength laser is tunable from 1542 to 1560 nm over a range of 18 nm, with a signal-to-noise ratio of 40 dB and the 3-dB linewidth of 0.096 nm. Furthermore, by appropriately rotating the polarization controllers and changing the pump power, wavelength continuously tunable dual- and triple-wavelength laser output is also experimentally demonstrated, and the wavelength selection and switching can be achieved by adjusting the polarization controllers in the cavity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 814006 (2011)
Machine Vision
Occlusion Handling Method for Multiple Moving Objects Tracking Based on Multilevel Tracker Queues
Jin Biao, Hu Wenlong, and Wang Hongqi
A novel real-time multiple objects tracking algorithm is proposed to handle the problem of occlusion in the stationary situation. Moving objects are detected using the background subtraction based on ghost detection and selective background updating model, a stable object model fusing the hue and edge features is estabA novel real-time multiple objects tracking algorithm is proposed to handle the problem of occlusion in the stationary situation. Moving objects are detected using the background subtraction based on ghost detection and selective background updating model, a stable object model fusing the hue and edge features is established, and multilevel tracker queues are defined to solve the occlusion, including stable tracker queue, temporal tracker queue, lost tracker queue, and uncertain tracker queue. Then the algorithm achieves tracking multiple objects handling occlusion based on multilevel data association, and it solves the problems of new objects appearing, objects merging, and object disappearing based on different strategies. Experimental results show that our detection method could restrain ghosts and prevent the moving objects from being fused to the background. Also, the method could testify the robustness of the object model and the tracking method could effectively track the objects in the complicated situation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 815001 (2011)
Materials
Polarization Microscopy Study on Piezo-Optical Effect of Polymer Dispersed Liquid Crystal Films
Li Zhenyuan, Fan Zhixin, Li Jinwei, Zhao Yongfang, and Sun Yubao
The large size liquid crystal droplet of polymer dispersed liquid crystal (PDLC) films with piezo-optical effect is prepared, the photographs of polarization microscope with press compared with that one without press are given. The model of compressed liquid crystal droplet is proposed, the order of flattening that liqThe large size liquid crystal droplet of polymer dispersed liquid crystal (PDLC) films with piezo-optical effect is prepared, the photographs of polarization microscope with press compared with that one without press are given. The model of compressed liquid crystal droplet is proposed, the order of flattening that liquid crystal droplet turns from pellet to the flat one after compressed is defined, the relation between the order parameter and order of flattening with compressing is calculated. The transmittance distribution of liquid crystal droplet birefringence is simulated in Fortran, and the graph is made with Origin software, the results of computation and graph plotting conform with photographs of polarization microscope compressed, further more, the principle of piezo-optical effect of polymer dispersed liquid crystal films is presented..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 816001 (2011)
Periodic Nanoripples and Photoluminescence on ZnO:Al Film Induced by Femtosecond Laser Pulses
Zhou Kan, Feng Donghai, Li Xia, Jia Tianqing, Liu Jiansheng, and Xu Zhizhan
The periodic nanoripples on ZnO:Al films induced by 800 nm femtosecond laser pulses are prepared. The regularity and formation mechanism of surface periodical nanostructure are studied after it is irradiated by femtosecond laser of different energy flux densities. Using He-Ge laser as light source, the photoluminescencThe periodic nanoripples on ZnO:Al films induced by 800 nm femtosecond laser pulses are prepared. The regularity and formation mechanism of surface periodical nanostructure are studied after it is irradiated by femtosecond laser of different energy flux densities. Using He-Ge laser as light source, the photoluminescence spectra of ZnO:Al films and its relationship with periodical nanostructures are studied. It is shown that the enhancement of emission near the band gap results from the quenching effect by 800 nm femtosecond laser on ZnO:Al films and the increase in optical absorption of He-Ge laser by the nanoripples..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 816002 (2011)
Medical Optics and Biotechnology
Study of Light-Transport Properties of Human Pericardium Meridian
Deng Xin, Chen Changshui, Jiang Yifan, Liu Xiangrong, and Liu Songhao
The light-transport characteristics of the pericardium meridian and its surrounding non-meridian tissue are studied in vivo. An experimental scheme is established for noninvasively measuring the space distribution of diffuse light in an area including the pericardium meridian with the method of combination of dots and The light-transport characteristics of the pericardium meridian and its surrounding non-meridian tissue are studied in vivo. An experimental scheme is established for noninvasively measuring the space distribution of diffuse light in an area including the pericardium meridian with the method of combination of dots and matrix. The distribution of diffuse light in the area are studied integrally. Two obvious linear dips are observed on the 3D image of the distribution of diffuse light, and their location coincides with the tendons on the two sides of the pericardium meridian. The study suggests that with this method the space distribution of diffuse light on the surface of body can be measured effectively. The experimental data is processed with the method of cubic spline interpolation. The study suggests that there is a significant difference between the propagations along the meridian direction and the non-meridian direction (p<0.05). In the five specific directions the light attenuation along the pericardium meridian is significantly less than that along the other non-meridian directions. The larger the angle between the meridian direction and the non-meridian direction, the faster the diffuse light attenuates along this non-meridian direction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 817001 (2011)
Nonlinear Optics
Investigation on Rayleigh Scattering Waveform in Phase Optical Time Domain Reflectometer
Lü Yuelan, and Xing Yongwei
On the basis of theoretical calculation of one-dimensional pulse-response model of the Rayleigh backscattering in a singel mode fiber, theoretical simulations of Rayleigh waveforms for 1550 nm of nanosecond pulses in 80 m fiber in a phase optical time domain reflectometer (OTDR) are presented. By changing physical paraOn the basis of theoretical calculation of one-dimensional pulse-response model of the Rayleigh backscattering in a singel mode fiber, theoretical simulations of Rayleigh waveforms for 1550 nm of nanosecond pulses in 80 m fiber in a phase optical time domain reflectometer (OTDR) are presented. By changing physical parameters such as refractive index, laser frequency and pulse width, relations between waveforms and the physical parameters are given. With the increase of optical fiber′s refractive index, the drifting quantity of the first Rayleigh peak increases and the Rayleigh peak density decreases; with the increase of the laser frequency, the drifting quantity of the first Rayleigh peak shows a periodic attenuation oscillation, and the Rayleigh peak density increases accordingly; with the increase of the pulse width, the drifting quantity of the first Rayleigh peak dispalys a periodic attenuation oscillation, the Rayleigh peak density decreases, and the peak power increases..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 819001 (2011)
Optical Design and Fabrication
Optical System Design of Wide-Angle and High-Resolution Spaceborne Imaging Spectrometer
Xue Qingsheng, Huang Yu, and Lin Guanyu
Space remote sensing urgently requires wide-angle and high-resolution spaceborne imaging spectrometer. According to the research objective of wide angle and high resolution, the design method of firstly dividing field of view (FOV) and secondly dividing beam using dichroscope is developed. The principle of dividing FOVSpace remote sensing urgently requires wide-angle and high-resolution spaceborne imaging spectrometer. According to the research objective of wide angle and high resolution, the design method of firstly dividing field of view (FOV) and secondly dividing beam using dichroscope is developed. The principle of dividing FOV is analyzed. A reflective spaceborne imaging spectrometer is designed, which is composed of a pointing mirror, a 11.42° telecentric off-axis three-mirror anastigmatic (TMA) telescope and four Offner convex grating spectral imaging systems. The proper magnification is chosen for each spectral imaging system to match two types of detectors. Ray tracing and optimization are performed and analyzed by CODE V software. The results demonstrate that the modulation transfer function (MTF) for different spectral bands is more than 0.7, which satisfies the pre-designed requirement. The design method is proved to be feasible..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 822001 (2011)
Wave-Front Fitting Capability Analysis of 1.8 m Telescope′s Adaptive Secondary Mirror
Fan Xinlong, Guan Chunlin, and Rao Changhui
Wave-front fitting capability analysis is an important part of adaptive secondary mirror′s design. Fitting capability simulation of 1.8 m telescope′s adaptive secondary mirror based on finite element analysis (FEA) influence function is presented. Analysis results show that the 73-element adaptive secondary mirrors canWave-front fitting capability analysis is an important part of adaptive secondary mirror′s design. Fitting capability simulation of 1.8 m telescope′s adaptive secondary mirror based on finite element analysis (FEA) influence function is presented. Analysis results show that the 73-element adaptive secondary mirrors can fit the 44-term Zernike polynomials with lower fitting errors. Mean fitting errors of 10000 frames of Kolmogorov phase screens is about 0.0541. Invalidated actuators near pupil edge induce fitting capability to reduce fearfully. Since the 73-element adaptive secondary mirror has better fitting ability with an actuator broken, the scheme has been chosen as 1.8 m telescope′s adaptive secondary mirror..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 822002 (2011)
Analysis of Polishing Errors by Tool Paths and Optimization of Tool Paths
Shi Chunyan, Yuan Jiahu, Wu Fan, and Wan Yongjian
To solve the problem that the inerratic tool paths will bring the iterative errors between path and path to polished optical components, a new polishing tool path which is named random tool path is proposed. The way of random tool path polishing is carried out as follows. Firstly, the orders of polishing positions and To solve the problem that the inerratic tool paths will bring the iterative errors between path and path to polished optical components, a new polishing tool path which is named random tool path is proposed. The way of random tool path polishing is carried out as follows. Firstly, the orders of polishing positions and polishing paths are created by random tool path algorithm after the polishing positions of optical components are discretized. Secondly, the dwell times can be figured out from error distributions and material removal function. However, the actual dwell times are not the calculated values because the random polishing paths will affect the dwell times when each path scans through some polishing positions. So the next step is that the actual dwell times are computed by the offset method, and numerical control codes are produced with actual dwell times. Finally, the polishing process is performed in numerical control polishing machine. The experimental results show that the way of random tool path is disordered, and the disorder can make the iterative errors between path and path distribute equally, which can reduce the error on optical mirrors and improve the roughness..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 822003 (2011)
Optical Devices
Focal Depth Properties of Modified Fractal Zone Plate
Zhang Qinqin, Zhu Siwei, and Yuan Xiaocong
A modified fractal zone plate (FZP) with the character of extending the focal depth is proposed. Through calculating, the period and the structure of modified FZP with the parameter w are obtained. Within the Fresnel approximation, the diffractive field distribution and the corresponding factors of the transverse fieldA modified fractal zone plate (FZP) with the character of extending the focal depth is proposed. Through calculating, the period and the structure of modified FZP with the parameter w are obtained. Within the Fresnel approximation, the diffractive field distribution and the corresponding factors of the transverse field distribution such as superresolution factor G, Strehl ratio S and sidelobe strength M have been studied using the numerical method. The properties of modified FZP in different radial coordinates (r and r2) also have been studied. The study shows that the modified FZP in r coordinate have a great improvement of focal depth than conventional FZP. The analysis of the lateral and axial properties shows that the focal depth of the modified FZP is larger than the FZP under the broadband lighting..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 823001 (2011)
Analysis of Image Rotation for Aerial Remote Sensor with Three-Mirror Reflective Optical System
Yu Chunfeng, Ding Yalin, Hui Shouwen, Zhang Jingguo, and Chen Wei
Image rotation is one important aspect on influence and confinement of image quality. The image mirror non-synchronous rotation with scanning mirror will cause image rotation in the focal plane. Consequently, it will lead to the loss of ground information and the image resolution will decrease significantly. In order tImage rotation is one important aspect on influence and confinement of image quality. The image mirror non-synchronous rotation with scanning mirror will cause image rotation in the focal plane. Consequently, it will lead to the loss of ground information and the image resolution will decrease significantly. In order to improve the dynamic state resolution of aerial remote sensor, it is indispensable to analyze the image rotation of aerial remote sensor. According to the optical reflection vector theory, imaging characteristics of aerial remote sensor with three-mirror reflective optical system are studied. At first, a simple mathematic model is abstracted from the aerial remote sensor. In the Cartesian coordinate system, it can analyze the influence on image quality which is caused by scanning mirror rotation along the direction of position angle and plunge angle by the mathematic method of coordinate transformation. Scanning mirror rotations along directions of plunge and position angles produce image rotation and image motion, respectively. It will provide a theoretical basis for designing a mechanical structure to compensate for drift angle and for the control of integration time of time delayed and integration (TDI) CCD according to the analysis. Test results show that the rotation synchronous error is less than one-third of pixel size and that prime images can be acquired without any blurring. Thereby, the modulation transfer function (MTF) of optical system can be improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 823002 (2011)
Physical Optics
Propagation Properties of Controllable Dark-Hollow Beams in Uniaxial Crystals
Zhang Weilin, Zhang Tingrong, Li Yantao, Huang Yongchao, Song Hongyuan, and Bao Jianqin
Based on the paraxial vectorial theory of beam propagating in uniaxial anisotropic media, the propagation equations of beam in uniaxial crystal are obtained. By using these equations, the propagation of controllable dark-hollow beam (CDHB) in uniaxial crystal is studied, and the field distribution expression of propagaBased on the paraxial vectorial theory of beam propagating in uniaxial anisotropic media, the propagation equations of beam in uniaxial crystal are obtained. By using these equations, the propagation of controllable dark-hollow beam (CDHB) in uniaxial crystal is studied, and the field distribution expression of propagation transformation of this beam in uniaxial crystal is obtained. By using the derived expressions, numerical calculation examples have been presented to illustrate its propagation properties. It shows that the distribution of intensity is greatly affected by controllable parameter ξ and the beam order N when the CDHBs propagate in uniaxial crystal. With the increase of parameter ξ, the size of dark region of the beam also increases, and the intensity decreases. The study also finds that when the beam order N increases, the size of the dark region of beam also increases, but the intensity decreases. With the increasing of the beam transformation distance z, the central intensity will increase gradually, and the distribution of intensity does no longer keep the original nature of hollow..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 826001 (2011)
Quantum Optics
Temperature Dependence of Effective Mass of Weak-Coupling Polaron in a Quantum Rod
Eerdunchaolu, Wuyunqimuge, and Han Chao
The influences of temperature on the effective mass of the weak-coupling polaron in an asymmetric parabolic quantum rod are studied based on Tokuda-Lee-Low-Pines variational method. The change law of the effective mass m* of the weak-coupling polarons with the aspect ratio e′ of the quantum rod, the electron-phonon couThe influences of temperature on the effective mass of the weak-coupling polaron in an asymmetric parabolic quantum rod are studied based on Tokuda-Lee-Low-Pines variational method. The change law of the effective mass m* of the weak-coupling polarons with the aspect ratio e′ of the quantum rod, the electron-phonon coupling strength α and the temperature parameter γ are derived. Numerical results indicate that the horizontal effective mass m*‖ and the vertical effective mass mz of the weak-coupling polaron in quantum rod will increase with the increase of the electron-phonon coupling strength α, and decrease with the increase of temperature T. The horizontal effective mass m*‖ of the polaron will increase with the increase of the aspect ratio e′ of the quantum rod. On the contrary, the vertical effective mass mz of the polaron will decrease with the increase of the aspect ratio e′..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 827001 (2011)
Remote Sensing and Sensors
A High-Speed CMOS Image Sensor for Real-Time Vision Chip
Fu Qiuyu, Lin Qingyu, Zhang Wancheng, and Wu Nanjian
A high-speed CMOS image sensor for real-time vision chip is proposed. The high-speed CMOS image sensor consists of CMOS photodiode array, correlated double sampling (CDS) array, programmable gain amplifier (PGA) array, area-efficient single-slope analog-to-digital converter (ADC) array and controller circuit. It can peA high-speed CMOS image sensor for real-time vision chip is proposed. The high-speed CMOS image sensor consists of CMOS photodiode array, correlated double sampling (CDS) array, programmable gain amplifier (PGA) array, area-efficient single-slope analog-to-digital converter (ADC) array and controller circuit. It can perform the image capturing and row-parallel signal processing. It outputs digital signal or digital image at a frame rate of over 1000 frame/s. It can reduce the fixed pattern noise (FPN) and amplify (or shrink) the output signals of the photodiode array to maintain the amplitude of the signal in row-parallel fashion. It can continuously perform 8-bit ADC conversion in row-parallel. A 128 pixel×128 pixel image sensor with 128 rows of CDS, PGA and single-slope ADC is fabricated by using 0.18 μm 1P6M CMOS process. The chip size is 2.2 mm×2.6 mm. The measured results demonstrate that the designed chip can perform high-speed real-time optical signal capturing and processing. It can be applied to the real-time vision chip system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 828001 (2011)
Scattering
Study on Light Backscattering by Spheroid with Inclusion
Sun Xianming, Wang Haihua, and Shen Jin
A method is described for the calculation of light-scattering properties of randomly oriented, axially symmetric spheroid particles with inclusion, in the framework of the T-matrix theory. Both the core and the shell can be axially symmetric nonspherical particles, and the inner and outer layers can be concentric or ecA method is described for the calculation of light-scattering properties of randomly oriented, axially symmetric spheroid particles with inclusion, in the framework of the T-matrix theory. Both the core and the shell can be axially symmetric nonspherical particles, and the inner and outer layers can be concentric or eccentric. Based on the model of spheroid particle with inclusion, light scattering characteristics of water aerosols with an absorptive core are calculated. The effects of core size, shape and position on the light backscattering characteristics are analyzed. It is suggested that light scattering properties in the backscattering region are sensitive to the shape, size, position of the core and the shape of the shell..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 829001 (2011)
Spectroscopy
Study on Picosecond Luminescence Dynamics of ［Ru(bpy)3］(ClO4)2 and ［Ru(bpy)2HPIP］(ClO4)2
Xu Zhongyang, Wang Lili, Ni Quanfeng, Chao Hui, Wang Hui, Zhang Lei, and Ji Liangnian
The luminescence properties of two kinds of ruthenium complexes, ［Ru(bpy)3］(ClO4)2 and ［Ru(bpy)2HPIP］(ClO4)2, are studied by steady-state and transient emission spectroscopy. The steady-state luminescence spectrum shows that ［Ru(bpy)2HPIP］(ClO4)2 has a weaker luminescence intensity. And the transient emission spectrum The luminescence properties of two kinds of ruthenium complexes, ［Ru(bpy)3］(ClO4)2 and ［Ru(bpy)2HPIP］(ClO4)2, are studied by steady-state and transient emission spectroscopy. The steady-state luminescence spectrum shows that ［Ru(bpy)2HPIP］(ClO4)2 has a weaker luminescence intensity. And the transient emission spectrum exhibits that there is a fast component within the excited-state relaxation of ［Ru(bpy)2HPIP］(ClO4)2, which may be due to the hydrogen-bonding between metal-ligand-charge-transfer (MLCT) state and solvent molecules. But the measured result of their nanosecond transient luminescence indicates that they have the same transient luminescence decay process. And this decay process accords with the energy gap law. It maybe corresponds to the excited-state relaxation of the MLCT state without combination with the solvent molecules..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 830001 (2011)
X-Ray Optics
Simulation on Focusing Performance of X-Ray Multilayer Laue Lens for 8 keV X-Ray
Li Haochuan, Huang Qiushi, Zhu Jingtao, and Wang Zhanshan
A nanometer-scale focused spot of hard X-ray can be achieved by multilayer Laue lenses (MLLs). X-ray propagation in MLL is analyzed using dynamical diffraction theory. The focusing performance of tilted MLL is calculated for 8 keV X-ray. The results show that a focused beam size of 5.7 nm and a mean efficiency of 26% cA nanometer-scale focused spot of hard X-ray can be achieved by multilayer Laue lenses (MLLs). X-ray propagation in MLL is analyzed using dynamical diffraction theory. The focusing performance of tilted MLL is calculated for 8 keV X-ray. The results show that a focused beam size of 5.7 nm and a mean efficiency of 26% can be obtained by a tilted MLL with an outmost zone thickness of 5 nm. MLL is proved theoretically to be an effective method to focus X-ray beam..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 834001 (2011)
Study of Multi-Component Sample Using Quantitative X-Ray Phase Contrast Imaging
Ren Yuqi, Zhou Guangzhao, Wang Yudan, Xie Honglan, Deng Biao, Du Guohao, and Xiao Tiqiao
The multi-component object has received broadly investigation and application, however, how to detect and measure the quantitative structural information accurately is still an urgent problem. Therewith, a multi-component model is constructed. Combined with X-ray phase contrast imaging (XPCI) and phase retrieval (PR), The multi-component object has received broadly investigation and application, however, how to detect and measure the quantitative structural information accurately is still an urgent problem. Therewith, a multi-component model is constructed. Combined with X-ray phase contrast imaging (XPCI) and phase retrieval (PR), systematic analysis of effects of the density difference of each component on the image contrast and precision of PR are conducted by simulation and experiment. The results show that XPCI and PR can provide a new method for nondestructively quantitative study of multi-component objects with high resolution and accuracy, which will play an important role in material sciences and biomedical applications, especially in the multilayer inertial fusion capsule and vascular imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 8, 834002 (2011)
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