Contents
2014
Volume: 34 Issue 5
47 Article(s)
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Research Article
Radiation Measurement Method for Infrared Small Targets
Chang Songtao, Zhang Yaoyu, Sun Zhiyuan, and Zhu Wei
During a radiation measurement mission, the target size may be too small or quite far away, which results in small infrared target images that can not be measured directly as an extended source. However, the target image tends to occupy several pixels, and therefore can not be treated as a traditional point source. AimDuring a radiation measurement mission, the target size may be too small or quite far away, which results in small infrared target images that can not be measured directly as an extended source. However, the target image tends to occupy several pixels, and therefore can not be treated as a traditional point source. Aiming at this problem, a small target radiation characteristics measurement method, based on the traditional measurement method of point source is proposed. The imaging characteristics of small targets are studied by experiments and theoretical analysis for the purpose to explain the difference between extended source and small target. A formula for small target radiation measurement is deduced by subtracting the background radiance from the target area. Finally, a mid-wave infrared imaging system is used for small target radiometric experiments, and the results indicate that the proposed method is effective..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 504001 (2014)
Atmospheric Optics and Oceanic Optics
Thermosonde Measurement of Temperature Structure Parameter and Temperature Spectral Power-Law Exponent Profile in the Lower Stratosphere
Wu Xiaoqing, Huang Honghua, Qian Xianmei, Wang Ping, and Cui Chaolong
The temperature structure function C2T(h)(r1=0.5 m, r2=1 m) and power-law exponent α(h) of the temperature fluctuation spectrum as functions of altitude are obtained by a novel thermosonde. The thermosonde provides two-channels for micro-thermal probes in different configurations. This arrangement can not only measure The temperature structure function C2T(h)(r1=0.5 m, r2=1 m) and power-law exponent α(h) of the temperature fluctuation spectrum as functions of altitude are obtained by a novel thermosonde. The thermosonde provides two-channels for micro-thermal probes in different configurations. This arrangement can not only measure temperature, humidity, pressure, wind speed and direction, refractive index structure constant profile, Fried parameter, seeing, isoplanatic angle, coherence time, but also provide power-law exponent profile of the temperature fluctuation spectrum. It is found the difference between α(h) and Zilberman′s three-layer model in the free troposphere. These results are useful for optical propagations, optical communications, remote sensing and numerical models of atmospheric turbulence..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 501001 (2014)
Diffraction and Gratings
An Iteration-Based Phase Retrieval Algorithm in Liquid-Crystal Phased Array
Zhuo Jingyi, Kong Lingjiang, Zhou Jianhua, Liu Xin, and Zhang Xiaoguang
In liquid-crystal phased array, the actual wavefront may deviate from the ideal wavefront, since the actual performance depends significantly on voltage quantization, phase sag, fringing effect, the manufacturing process of liquid crystal device, and so on. Thus, to meet the requirement of beam scanning in the view fieIn liquid-crystal phased array, the actual wavefront may deviate from the ideal wavefront, since the actual performance depends significantly on voltage quantization, phase sag, fringing effect, the manufacturing process of liquid crystal device, and so on. Thus, to meet the requirement of beam scanning in the view field, the voltage is constantly adjusted according to deviation between the actual wavefront phase and the ideal, such that the actual phase can approximate to the ideal phase as much as possible. This has been one of the key problems in liquid crystal phased array. For retrieving the phase in liquid crystal phased array, a novel output-plane-based phase retrieval algorithm with wavefront iteration is presented. Specifically, the wavefront phase distribution is retrieved by using the knowledge of intensity measurements in three output-planes. Compared with the algorithms depended on the two output planes, our algorithm can achieve high precision. Moreover, the algorithm exploits angular spectrum transfer function, thus the results are more reliable. The theoretical analysis and simulation experiments indicate that this algorithm enjoys advantages in terms of precision and efficiency simultaneously..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 505001 (2014)
Fiber Optics and Optical Communications
High-Order Tilted Fiber Bragg Gratings Carved with Femtosecond Laser
Chen Chao, Yang Xianhui, Wang Chuang, and Yu Yongsen
High-order tilted fiber Bragg gratings (HO-TFBG) in non-photosensitized single mode fiber are demonstrated with femtosecond laser micro-nano machining technique. To realize the tilted refractive index modulation in fiber core and partial cladding, a high order phase mask is used to generate periodic light intensity whiHigh-order tilted fiber Bragg gratings (HO-TFBG) in non-photosensitized single mode fiber are demonstrated with femtosecond laser micro-nano machining technique. To realize the tilted refractive index modulation in fiber core and partial cladding, a high order phase mask is used to generate periodic light intensity which is focused on to the tilted fiber with a lateral scanning. Using this method, three groups of cladding mode resonances in relation with high order Bragg resonance are detected in the wavelength range from 1200 nm to 1700 nm. Thus it carries more informations compared with ultraviolet tilted fiber Bragg gratings (UV-TFBG), especially in multi-parameters monitoring. The refractive index, axial strain and temperature sensing characteristics of the HO-TFBG are also studied. Besides, due to the femtosecond laser material modification, this device shows a good ability in high temperature stability, which has potention in chemical and physical sensing in harsh circumstances..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 506001 (2014)
Two-Dimensional Coherent Optical En/Decoder Based on Parallel-Cascaded Coupled Micro-Ring Reflector
Ji Zhe, Jia Dagong, Zhang Haiwei, Zhang Hongxia, Zhang Delong, Liu Tiegen, and Zhang Yimo
One of the key modules in the integrated optical code division multiple access (OCDMA) system is highly integrated, easily tuning optical en/decoder. Two-dimensional coherent optical en/decoder based on parallel-cascaded coupled micro-ring reflector is proposed. This device can enable simulaneonsly to tune the wavelengOne of the key modules in the integrated optical code division multiple access (OCDMA) system is highly integrated, easily tuning optical en/decoder. Two-dimensional coherent optical en/decoder based on parallel-cascaded coupled micro-ring reflector is proposed. This device can enable simulaneonsly to tune the wavelength hopping of dual-ring down load end and the phase of intergrated phase shifter in the bus. According to the coupled mode theory, transfer matrix equations for this cascaded reflector are established. The radii for this dual-ring resonator are 50 μm and 48 μm, respectively. The resonant central wavelengths for each reflector are 1535, 1535.2, 1535.4, 1535.6 nm. Each reflected spectrum has a 3 dB bandwidth of 0.14 nm with a channel spacing of 17 GHz, ensuring the accuracy of the transmitted and received signals. Correspondingly, the number of possible users is 96 with autocorrelation peak sidelobe ratio (P/W) about 5 and cross-correlation peak ratio (P/C) about 7..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 506002 (2014)
Research on the Controllable Frequency Octupling Technology for Generating Optical Millimeter-Wave by External Modulator
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel scheme is proposed for generating high quality frequency octupling signal, which can be used in millimeter-wave radio-over-fiber (RoF) system. It′s based on an integrated structure of triple-parallel Mach-Zehnder modulator (MZM) by using two adding one structure. Two kinds of redundant sidebands are well eliminA novel scheme is proposed for generating high quality frequency octupling signal, which can be used in millimeter-wave radio-over-fiber (RoF) system. It′s based on an integrated structure of triple-parallel Mach-Zehnder modulator (MZM) by using two adding one structure. Two kinds of redundant sidebands are well eliminated by adopting 90\O of the electric phase-difference between two sub Mach-Zehnder modulators (sub-MZMs), driven by radio frequency (RF) signal. Moreover, bias of the third sub Mach-Zehnder modulator (sub-MZM) is tailored to get the best signal. The simulation results show that the radio frequency spurious suppression ratio (RFSSR) is as high as 38.3315 dB under the condition of conventional extinction ratio (30 dB) without any optical or electrical filter. Furthermore, optical sideband suppression ratio (OSSR) can reach as high as 61.22878 dB at ideal extinction ratio (100 dB). For not only conventional condition but also the ideal case, the scheme can get high quality millimeter-wave signal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 506003 (2014)
Study on High Precision Disciplined Time-Frequency Transferring Experiments through Optical Fiber Link
Li Xiaoya, Zhu Yong, Lu Lin, Wu Chuanxin, Jing Jisong, and Li Delong
The basic principle of high precision disciplined time-frequency transfer through optical fiber link, the analysis of error sources and the structure of the disciplined clock system are expatiated. Experiments through 100 km optical fiber are done when the temperature slowly changes and extremely changes. The result prThe basic principle of high precision disciplined time-frequency transfer through optical fiber link, the analysis of error sources and the structure of the disciplined clock system are expatiated. Experiments through 100 km optical fiber are done when the temperature slowly changes and extremely changes. The result presents that the peak-to-peak value of synchronization error is smaller than 400 ps. And the performance of the system can satisfy the demand of high precision and synchronization time transfer between commercial atomic clocks..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 506004 (2014)
Influence of Thermal Effect Caused by Piezoelectric Transducer on Interferometric Demodulation for Fiber Bragg Grating Sensor
Yu Youlong, Tan Ling, Li Qian, and Wang Xianhu
A scanning unbalanced Michelson interferometer is used to act as a demodulator in fiber Bragg grating sensor system. Additional phase-shift, caused by thermal noise, is demonstrated to occur in the output of the interferometer theoretically and experimentally, when a piezoelectric ceramic (PZT) is acted as the driving A scanning unbalanced Michelson interferometer is used to act as a demodulator in fiber Bragg grating sensor system. Additional phase-shift, caused by thermal noise, is demonstrated to occur in the output of the interferometer theoretically and experimentally, when a piezoelectric ceramic (PZT) is acted as the driving element of the interferometer. To eliminate the thermal noise, a new method by separating the driving element from the interference device is introduced. Comparing with the conventional with/without temperature controlling interferomtric demodulation scheme, thermal noise is demonstrated to be disappeared experimentally in the new scheme, and there is also no thermal inertia needed to be overcome. The predicted resolution of the system is 5.5 nε, and the experimental sensitivity is 0.9609°/με..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 506005 (2014)
Imaging Systems
Fast Registration Algorithm Design and Analysis of TDI CCD Camera Assembly Imaging
Chang Lin, Jin Guang, and Yang Xiubin
In order to solve the problem of multi pieces of TDI CCD stitching pixel mismatch in satellite flexible transformation multimodal imaging, a kind of pixel matching algorithm which can realize overlapping and displacement pixel fast assembly and registration of TDI CCD camera is proposed. Through the analysis of multi pIn order to solve the problem of multi pieces of TDI CCD stitching pixel mismatch in satellite flexible transformation multimodal imaging, a kind of pixel matching algorithm which can realize overlapping and displacement pixel fast assembly and registration of TDI CCD camera is proposed. Through the analysis of multi pieces of TDI CCD assembly imaging pixel mismatch phenomenon caused by the variation of image motion velocity vector in focal plane during the process of satellite side swing imaging, the imaging velocity vector ray tracing and the homogeneous coordinate transformation method is designed. Based on this method, the image motion velocity and drift angle which influence image mismatch during the process of satellite side swing imaging and the number of pixel in direction of longitudinal displacement and transverse overlapping of two pieces of TDI CCD assembly imaging are calculated. Three-axis air flotation turntable attitude simulation system and a TDI CCD camera are used in experiment to verify the pixel matching algorithm of two pieces of TDI CCD assembly imaging. TDI CCD camera of viewing angle of 10°, after an assembly period, the original number of longitudinal displacement and transverse overlapping pixels of two pieces of TDI CCD assembly imaging turns from 148.5 and 50 to 137 and 49, respectively, which is consistent with theoretical result in longitudinal displacement direction and has a deviation of only 0.1 pixel in transverse overlapping direction. Compared with the theoretical and experimental result, the design of fast registration algorithm of calculation of longitudinal displacement and transverse overlapping pixel can solve the accuracy of TDI CCD assembly imaging, which guarantees image pixel matching and obtain high quality images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511001 (2014)
Improved Khler Ilumination-Based Full-Field Optical Coherence Tomography System
Zhu Xiaomeng, Gao Wanrong, and Zhu Yue
A Linnik interference microscope-based full-field optical coherence tomography (FF-OCT) system is developed to obtain high-quality optical sectional images. Compared with other FF-OCT systems illuminated with optical fiber (OF) bundle, the improved Khler illumination arrangement with a halogen lamp is used in the propA Linnik interference microscope-based full-field optical coherence tomography (FF-OCT) system is developed to obtain high-quality optical sectional images. Compared with other FF-OCT systems illuminated with optical fiber (OF) bundle, the improved Khler illumination arrangement with a halogen lamp is used in the proposed FF-OCT system. A tomographic image of an Intel Pentium 4 chip is retrieved from four sequential phase-shifted interferograms by using a four-step algorithm. The experimental results confirm the feasibility of the proposed imaging system. The proposed improved Khler illumination-based FF-OCT system is characterized by its use of simple elements and lower cost, providing a simple and convenient method for high-resolution OCT imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511002 (2014)
Computational Reconstruction for Integral Imaging with Sampled Elemental Images
Wang Yu, and Piao Yan
High-quality integral imaging (II) system requires collecting and storing large amounts of image data. To reduce the amount of data demanded by II display part during computational reconstruction, a novel computional reconstruction method is proposed. Conventional computational reconstruction needs to use each elementaHigh-quality integral imaging (II) system requires collecting and storing large amounts of image data. To reduce the amount of data demanded by II display part during computational reconstruction, a novel computional reconstruction method is proposed. Conventional computational reconstruction needs to use each elemental image. However, in the proposed method, elemental images array recorded by CCD camera are periodically sampled, and multiple view images can be reconstructed by only utilizing the sampled elemental images. This method makes full use of the matching pixel for the adjacent elemental images in integral imaging. Therefore, the unsampled elemental image information can be replaced by the matching pixel in the sampled elemental images to reconstruct multiple view images. Thus, the amount of data required for reconstruction can be reduced by using this proposed method, which can provide flexibility for II display part with different performances, and reduces the requirements for the storage capacity and transmission bandwidth for integral images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511003 (2014)
Four Dimensional Spectral Imager with Integral Field Fiber Bundle
Li Libo, Feng Yutao, Wang Shuang, Bai Qinglan, and Hu Bingliang
As one of the most important development of remote sensing, spectral imager has been widely used in military, geognosy, ocean and atmosphere measurement. However, the classic spectral imager, neither dispersive spectral imager nor Fourier transform spectrometer, which has to take multiple exposures to scan spectral datAs one of the most important development of remote sensing, spectral imager has been widely used in military, geognosy, ocean and atmosphere measurement. However, the classic spectral imager, neither dispersive spectral imager nor Fourier transform spectrometer, which has to take multiple exposures to scan spectral data cube, do not suit with the situation that the scene change too fast. Four-dimensional (4D) fiber reformatting spectral imager, in which a special optical fiber bundle sits in the image plane of the telescope and has linearly aligned at the entrance to the spectrograph, can capture three-dimensional (3D) spectral data cube in a single exposure. So it enable to measure fast moving target or fast changing scene. A breadboard system in the laboratory is described, the average spectral resolution of the system is 4.2 nm in visible range, and a good imaging result of color target is got. The fiber bundle errors are analyzed, and the calibrating method is given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511004 (2014)
Image Reconstruction Method of Fourier Telescope Based on Iteration
Zhou Zhisheng, Xiangli Bin, Zhang Wenxi, and Li Yang
To improve the quality of the ultimate image, the conventional image reconstruction method and the phase retrieval method are combined and an image reconstruction method of Fourier telescope based on iteration is proposed. A direct reconstructed image is acquired by inverse Fourier transform of the measured Fourier comTo improve the quality of the ultimate image, the conventional image reconstruction method and the phase retrieval method are combined and an image reconstruction method of Fourier telescope based on iteration is proposed. A direct reconstructed image is acquired by inverse Fourier transform of the measured Fourier component, and then a threshold image of the direct reconstructed image acts as the initial input for the phase retrieval reconstruction algorithm and a superior image is reconstructed through iteration. Simulation result shows that, compared with direct reconstructed image, the Strehl ratio of reconstructed image from the iterative method raises from 0.83 to 0.88 (50 signal-to-noise ratio) and from 0.89 to 0.93 (100 signal-to-noise ratio), besides the peak value signal-to-noise raises from 17 dB to 19 dB (50 signal-to-noise ratio) and from 20 dB to 22 dB (100 signal-to-noise ratio)..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511005 (2014)
Looking Around Corners and Through Turbid Media with Projector
Jin Haoqiang, Shi Jianhong, Peng Jinye, and Zeng Guihua
Turbid media has a great influence on traditional imaging, which may even result in complete failure when scattering becomes serious enough. It has attracted extensive attentions in practical applications to obtain high resolving images through turbid media. A projector is applied in the ghost imaging (GI) experiment, Turbid media has a great influence on traditional imaging, which may even result in complete failure when scattering becomes serious enough. It has attracted extensive attentions in practical applications to obtain high resolving images through turbid media. A projector is applied in the ghost imaging (GI) experiment, which achieves the goals of both looking around corners and imaging through turbid media. The images of objects can be obtained with a bucket detector which has no spatial resolution. The experiment results with that of the traditional imaging are compared and the influence factors on resolution are analyzed. It is feasible to image around corners through turbid media by means of simple illuminants, such as projectors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511006 (2014)
Optical Design of Airborne Hyperspectral Imaging System with Wide Field of View
Dong Wei, Zhou Jinsong, Nie Yunfeng, and Huang Min
In order to meet the development needs of airborne hyperspectral imaging system, an airborne hyperspectral imaging system with wide field of view is presented. In the system, the pre-telescope system is a transmission system with wide field and wide-spectrum, and the hyperspectral imager is an improved Féry-prism In order to meet the development needs of airborne hyperspectral imaging system, an airborne hyperspectral imaging system with wide field of view is presented. In the system, the pre-telescope system is a transmission system with wide field and wide-spectrum, and the hyperspectral imager is an improved Féry-prism relay system based on Offner secondary. Zemax multi-configuration is used twice in the system design process, and we attempt to design the improved Féry-prism of Offner secondary as a hyperspectral imager for the first time. Besides, the Féry-prism hyperspectral imager is firstly integrated as hyperspectral imaging system for system analysis. The design is innovative both on the structure and methods. The design results show that the field of view of the system is 28°, when the height of the airborne payload is 5 km, Swath width with the total system is 2.493 km, and the ground sampled distance is 0.6 m. The full spectral modulation transfer functions of field half right and field half left are greater than 0.6. Keystones and smiles about maxium are close to 0.2 pixel, and the image quality closes to the diffraction limit..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511007 (2014)
Microscopic PIE Imaging With Theory of Compressive Sensing
He Jing, Liu Cheng, Gao Shumei, Wang Jicheng, Wang Yueke, and Zhu Jianqiang
In order to overcome the problem of large amounts of data in PIE imaging, the theory of compressive sensing is adopted for PIE imaging. Diffraction patterns are sparsified and compressed, which can reduce the amount of data requiring save. The original distribution of scattering spot can be reconstructed with subspace In order to overcome the problem of large amounts of data in PIE imaging, the theory of compressive sensing is adopted for PIE imaging. Diffraction patterns are sparsified and compressed, which can reduce the amount of data requiring save. The original distribution of scattering spot can be reconstructed with subspace persuit (SP) or orthogonal matching pursuit (OMP) tuning algorithm in the retrieval process, then image reconstruction is realized using regular PIE algorithm. Simulation and experimental results show that the images can be reconstructed perfectly when the compression ratio is 30%. SP algorithm is more appropriate than OMP algorithm for PIE imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 511008 (2014)
Instrumentation, Measurement and Metrology
Sub-Micron Precision Measurement of Radius of Curvature and Uncertainties Analysis
Peng Shijun, and Miao Erlong
For the demanding of high precision optical system, a vertical Fizeau type interferometer, combining with dual-frequency laser displacement measuring interferometer, achieve submicron precision measurement of radius of curvature (ROC) in this article. In order to verify the credibility of the measurement system, a seriFor the demanding of high precision optical system, a vertical Fizeau type interferometer, combining with dual-frequency laser displacement measuring interferometer, achieve submicron precision measurement of radius of curvature (ROC) in this article. In order to verify the credibility of the measurement system, a series of optical parts with different ROC are measured by two different reference transmission spherical respectively. Take the polished SiC sphere as an example, the main factors causing the measurement errors are analyzed in detail. Combining with the uncertainty theory, the uncertainties of the measurement results of ROC for SiC sphere is about 0.13 μm (a level of confidence of approximately 95% assuming a normal distribution), which demonstrate the measurement system meets the requirement of sub-micron accuracy measurement of ROC. The correctness of the final results measured is verified through the cross measurement of the same component by the coordinate measurement machine..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512001 (2014)
Microscopic Three-Dimensional Deformation Measurement System Based on Digital Image CorrelationRen Maodong
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel microscopic full field three-dimensional deformation measurement system is proposed and implemented, which is based on stereo microscope and digital image correlation method. In order to realize the calibration of stereo microscope, a new high precision distortion model is offered by reconstructing a B-spline sA novel microscopic full field three-dimensional deformation measurement system is proposed and implemented, which is based on stereo microscope and digital image correlation method. In order to realize the calibration of stereo microscope, a new high precision distortion model is offered by reconstructing a B-spline surface. By acquiring images of the high precision planar calibration target designed independently and constructing the relationship between the target plane and the free distortion image planes, a form of space B-spline surface is established. Then, a high-efficiency image correlation method is realized by using a symmetric sub-pixel refinement strategy. The process for three-dimensional measurements using the proposed system is presented. Experimental results show that, the root-mean-sqsuare (RMS) error of the calibration results for stereo microscope system is 0.03 pixel, the displacement measurement accuracy is better than 0.2 μm, and the standard deviation of strain measurement error is no more than 100 με. At the same time, the experimental results indicate that the proposed system is accurately and can solve the problem of microscopic full field three-dimensional deformation measurement comprehensively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512002 (2014)
Research on Technology of Ground-Based Infrared Radiation Feature Measurement for Space Target
Liu Yingqi, and Liu Xiangyi
In order to precisely measure infrared radiation characteristics of space target, a radiometric calibration method is presented based on the internal calibration blackbody and external natural star with known infrared spectral characteristics, and on the basis of the proposed method corresponding radiation measuring maIn order to precisely measure infrared radiation characteristics of space target, a radiometric calibration method is presented based on the internal calibration blackbody and external natural star with known infrared spectral characteristics, and on the basis of the proposed method corresponding radiation measuring mathematical model is established. Internal calibration blackbody is used to measure the responsivity of each detector pixel involving the back half light path of the telescope, and the external natural star is used to estimate equivalent transmittance of the atmosphere near target region with the first half light path of the telescope. A large number of infrared radiation intensity measurement experiment show that the accuracy can be better than 15% within 3~5 microns band on the 1.2-m ground based telescope when the target has strong infrared energy reference star and the exoatmosphere irradiance is higher than 1×1016 W/cm2 order of magnitude. The method can overcome the effects of the atmospheric path radiation, extinction and large diameter radiation calibration source on the measurement precision about infrared radiation intensity of exoatmosphere space target, and it is suitable for calibrating of the ground based infrared radiation measurement system with large diameter and measuring of the infrared radiation characteristics of exoatmosphere space target with high precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512003 (2014)
A New Model of Three-Dimensional Shape Measurement System Based on Fringe Projection
An Dong, Gai Shaoyan, and Da Feipeng
A novel model of three-dimensional (3D) shape measurement in fringe projection profilometry (FPP) system is proposed, which doesn′t need to meet the constraints of the link of the two optical centers being parallel to the reference plane, the axis of imaging system being perpendicular to the reference plane and the twoA novel model of three-dimensional (3D) shape measurement in fringe projection profilometry (FPP) system is proposed, which doesn′t need to meet the constraints of the link of the two optical centers being parallel to the reference plane, the axis of imaging system being perpendicular to the reference plane and the two axes intersecting on the reference plane. This new model just requires the sinusoidal fringes projected on the reference plane are parallel to each other, so it is easy to implement the adjustment of the FPP system. The undetermined coefficients of the achieved phase-to-height relationship are irrelevant to the coordinates of imaging points. The coefficients can be obtained by means of least square method by sampling a number of points, not every one, so the calibration time is reduced a lot. The experiments demonstrate that the adjustment of the FPP system is simple, so the speed of the system calibration is improved greatly. Moreover, the accuracy of this new 3D measurement system is high, and it can measure the objects with complex surface shapes. Therefore, the novel method enhances the practicability of FPP system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512004 (2014)
Fast Three-Dimensional Shape Measurement Technique by Means of Wavelet Transform Based on Parallel Computing
Yu Cheng, Li Sikun, and Wang Xiangzhao
In order to improve the speed of phase demodulation in three-dimensional (3D) shape measurement system, according to different theories of parallelism, two different approaches of parallel one-dimensional (1D) continuous wavelet transform fringe pattern demodulation have been proposed. Computer simulation and experimenIn order to improve the speed of phase demodulation in three-dimensional (3D) shape measurement system, according to different theories of parallelism, two different approaches of parallel one-dimensional (1D) continuous wavelet transform fringe pattern demodulation have been proposed. Computer simulation and experiment in multicore CPU computing platform show that, compared to serial phase demodulation, parallel fringe pattern phase demodulation technique keeps the computing precision while the processing speed is significantly improved: the experiment on processing 850 pixel×1000 pixel fringe pattern achieves 7.5 times speedup. Our solutions lay the foundation for the applying of fringe pattern demodulation technique by means of wavelet transform to real-time/ transient 3D shape measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512005 (2014)
An Equi-Phase Coordinate Calibration Method Based on Two Reference Planes
Dai Meiling, Yang Fujun, Dai Xiangjun, and He Xiaoyuan
Calibration is to transform the two-dimensional (2D) phase information to the height in fringe projection three-dimensional (3D) measurement. An equi-phase coordinate method based on two reference planes for calibrating fringe projection system is proposed. The surface height is calculated by a linear interpolation usiCalibration is to transform the two-dimensional (2D) phase information to the height in fringe projection three-dimensional (3D) measurement. An equi-phase coordinate method based on two reference planes for calibrating fringe projection system is proposed. The surface height is calculated by a linear interpolation using the coordinates where have the identical phase value of the object and the two reference planes, instead of using the absolute phase obtained by subtracting the phase of object from the reference plane in the same coordinate conventionally and building the function of the absolute phase and height, which is called equi-coordinate phase method. The proposed method can handle phase-to-height conversion and non-sinusoidal error caused by nonlinear respondence of the fringe projection system in one go. Theoretical and experimental analysis is given to prove the validity of the proposed calibration method. Results indicate that the root mean square (RMS) error produced by equi-phase coordinate method is less half of the equi-coordinate phase approach when the primary error source is from the non-sinusoidal fringe patterns..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512006 (2014)
An Alignment Method of the Telescope′s Primary and Second Mirrors Based on Astigmatic Decomposition
Zhang Xiaoming, Chen Hongbin, Wang Jihong, and Qi Bo
The alignment errors of primary and secondary mirrors can make the image blur. In order to improve the alignment precision of the telescope′s primary and secondary mirrors, an algorithm used to calculate the alignment errors based on astigmatic decomposition is presented. The algorithm makes use of the astigmatism iterThe alignment errors of primary and secondary mirrors can make the image blur. In order to improve the alignment precision of the telescope′s primary and secondary mirrors, an algorithm used to calculate the alignment errors based on astigmatic decomposition is presented. The algorithm makes use of the astigmatism itern of wavefront errors described by Zernike Polynomials to calculate the astigmatism produced by the different alignment errors independently. The character of the astigmatic decomposition algorithm is investigated based on a reflective coaxial (RC) telescope whose diameter is 1200 mm. It is obviously that the calculation errors increase along with the distance between the primary and secondary mirrors′ optical axes, while the two optical axes are in the different planes. An alignment algorithm is designed based on the astigmatic decomposition algorithm. The simulation alignment is done. The simulation shows that the alignment algorithm can align the optical system rapidly with a residual less than 5 μm and 0.5″, when the distance between two axes is less than 0.5 mm and the tilt of two axes is less than 0.1°. Simulation analysis demonstrates the feasibility of the alignment algorithm based on astigmatic decomposition..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 512007 (2014)
Lasers and Laser Optics
Wavelength Stabilization and Linewidth Narrowing of Laser Diode for Pumping Cs Vapor Laser
Feng Jiansheng, Yuan Xiao, Xiong Baoxing, Gao Fan, and Zhang Xiang
As referred to the laser diode with wavelength stabilization and linewidth narrowing required in pumping Cesium vapor lasers, volume Bragg gratings are employed as the external cavity output mirror and the effect of volume Bragg gratings with different diffraction efficiencies on output spectrum of external cavity laseAs referred to the laser diode with wavelength stabilization and linewidth narrowing required in pumping Cesium vapor lasers, volume Bragg gratings are employed as the external cavity output mirror and the effect of volume Bragg gratings with different diffraction efficiencies on output spectrum of external cavity laser diode is studied. It is demonstrated that the volume Bragg gratings with diffraction efficiencies of 24%, 32% and 37% can improve the laser′s output spectrum apparently. The lasing central wavelength is locked at 852 nm, and the linewidth is narrowed to 0.26 nm. The output wavelength rates of pumping current and operating temperature are less than 10.4 pm/A and 7.2 pm/℃, respectively. With the increase of diffraction efficiency, the external cavity ratio of this system is reduced from 91% to 86%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 514001 (2014)
Numerical Simulation of a PbSe Quantum Dot Doped Fiber Laser with a Ring Resonator
Cheng Cheng, and Yuan Fang
A PbSe quantum dot (QD) doped fiber laser of 1550 nm is simulated numerically by solving the rate equation and lasing propagation equation in a ring resonator, on the basis of experiment using the QDs hosted in ultraviolet (UV) gel as lasing medium. It is shown that the simulated results are consistent with the experimA PbSe quantum dot (QD) doped fiber laser of 1550 nm is simulated numerically by solving the rate equation and lasing propagation equation in a ring resonator, on the basis of experiment using the QDs hosted in ultraviolet (UV) gel as lasing medium. It is shown that the simulated results are consistent with the experiments observed before, including the pumping threshold, single/multi mode laser power varying with the pumping power, desirable doping concentrations, and single mode laser power varying with the outputting coupling ratio. The inversion condition of population density, N2/N1≥0.45, is given by investigating the laser power distributing along the longitudinal fiber, which can be explained by the cross-section ratio of absorption to emission at the 1550 nm. A rang of available doping concentration is determined by studying the effect of the doping concentration on the laser power..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 514002 (2014)
Machine Vision
Fusion of Global and Local Various Feature for Facial Expression Recognition
Li Yaqian, Li Yingjie, Li Haibin, Zhang Qiang, and Zhang Wenming
Principal component analysis (PCA) can only keep the global structure, while neighborhood preserving embedding (NPE) preserves the similarity between neighbor data, but ignores the difference between them. Focusing on the problems mentioned above, a feature extraction method is proposed by fusing global and local varioPrincipal component analysis (PCA) can only keep the global structure, while neighborhood preserving embedding (NPE) preserves the similarity between neighbor data, but ignores the difference between them. Focusing on the problems mentioned above, a feature extraction method is proposed by fusing global and local various feature, and is applied to facial expression recognition. PCA is used to preserve global structure and a local diversity scatter and a local similarity scatter is defined by manifold learning algorithms, combining with local maximum scatter difference criterion, the proposed method can efficiently preserve the variety of local manifold. The low dimensional feature is extracted by combining the global feature with local various feature for expression classification. The experiments on JAFFE and Cohn-Kanade facial expression databases indicate that compared with PCA, locality preserving progection (LPP), NPE and other methods, this method not only improves the recognition rate efficiently, but also needs the least dimensions when achieves the highest recognition rate, which demonstrates that this method is superior to others in recognition rate..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 515001 (2014)
Analysis and Improvement of Characteristic Points Extraction Algorithms in Camera Calibration
Li Lulu, Zhao Wenchuan, Wu Fan, and Liu Yong
In order to improve the camera calibration accuracy, characteristic points extraction method with high accuracy is needed. Three typical calibration patterns including checkerboard pattern, crossed sine fringe pattern, and Gaussian point matrix pattern are chosen. Corresponding characteristic points extraction algorithIn order to improve the camera calibration accuracy, characteristic points extraction method with high accuracy is needed. Three typical calibration patterns including checkerboard pattern, crossed sine fringe pattern, and Gaussian point matrix pattern are chosen. Corresponding characteristic points extraction algorithms are analyzed and compared, adding the comparison of accuracy in camera intrinsic parameters calibration, the best one is crossed sine fringe pattern based on Fourier phase analysis. To avoid the drawback that the Fourier method used in the crossed sine fringe pattern cannot handle with characteristic points located in the edge of the point matrix, a novel method that using phase-shift method instead of Fourier method is proposed to obtain the crossed phase. The new method can eliminate the indistinct affect in the edge of the point matrix caused by Fourier translation filtering, so to amplify the scope of application of crossed sine fringe pattern in camera calibration. The extrinsic parameters calibration experiment show that the new method is effective in handling point matrix including edge points, for the reprojection error keeps in original level..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 515002 (2014)
An Accurate and Real-Time Focal-Length Self-Calibration Method Based on Infinite Homography between Vanish Points
Cai Ming, Sun Xiuxia, Liu Shuguang, Xu Song, and Liu Xi
Based on the infinite homography relation between the vanish points on images captured in different camera positions and the relative position information, a self-calibration method is proposed to calibrate the focal-length of camera accurately. By projecting parallel lines in two positions, this method achieves a pairBased on the infinite homography relation between the vanish points on images captured in different camera positions and the relative position information, a self-calibration method is proposed to calibrate the focal-length of camera accurately. By projecting parallel lines in two positions, this method achieves a pair of vanish points in image plane, an infinite homography constraint is established and the focal-length is solved. Considering the parallel extent of lines that connecting corresponding optical centers and vanish points as the optimization index of Nelder-Mead nonlinear simplex method, focal-length optimization is achieved, the effect of image noises and rotation uncertainties are restrained effectively, and the accuracy of calibration result and algorithm robustness are improved greatly. Plenty of simulations show that this method proposed is both accurate, robust and real-timed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 515003 (2014)
Materials
Synthesis and Properties of BaMgSiO4:Eu2+/Eu3+ Phosphor with Color-Tunable White Lighting
You Panli, and Hu Yuebo
The BaMgSiO4:Eu2+/Eu3+ phosphors are prepared in air atmosphere by a conventional solid-state reaction, the properties of BaMgSiO4:Eu2+/Eu3+ phosphors are investigated through X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscope (SEM) and photoluminescence (PL). The results suggest that tThe BaMgSiO4:Eu2+/Eu3+ phosphors are prepared in air atmosphere by a conventional solid-state reaction, the properties of BaMgSiO4:Eu2+/Eu3+ phosphors are investigated through X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscope (SEM) and photoluminescence (PL). The results suggest that the emission spectra of Eu2+ and Eu3+ ions are both presented in the Eu-doped BaMgSiO4 phosphors under the excitation of 393 nm, and the emission intensity of Eu2+/Eu3+ can be changed with the NH4Cl contents to achieve tunable spectra from green light to white light. The PL intensity of Eu3+ is improved with increasing of NH4Cl contents, and the value of I Eu2+/Eu3+ is the smallest when adding 5% NH4Cl in the BaMgSiO4:Eu2+/Eu3+. The warm white light with international commission on illumination (CIE) chromaticity coordinates (0.37, 0.38) and color temperature CCT (4300 K) is obtained. BaMgSiO4:Eu2+/Eu3+ phosphor shows better thermal stability because the emission intensity measured at 200 ℃ is only decreased 15% compared with that measured at room temperature. The results show that BaMgSiO4:Eu2+/Eu3+ can be used as potential single-doped and single-composition white light emitting diode (LED) phosphors..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 516001 (2014)
Synthesis and Luminescence Properties of Terbium Doped Calcium Fluoride Green Phosphor
Liao Jinsheng, Liu Shaohua, Wang Ganzhen, and Nie Liling
A series of Tb3+ doped CaF2 phosphors with different Tb3+ concentrations are synthesized by the microemulsion system composed of cetyltrimethyl ammonium bromide (CTAB), n-butyl alcohol, cyclohexane and water under the hydrothermal environment. The crystal structure, particle size, morphology and composition of the fluoA series of Tb3+ doped CaF2 phosphors with different Tb3+ concentrations are synthesized by the microemulsion system composed of cetyltrimethyl ammonium bromide (CTAB), n-butyl alcohol, cyclohexane and water under the hydrothermal environment. The crystal structure, particle size, morphology and composition of the fluorescent powder are represented by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). Photoluminescence excitation spectra, emission spectra and luminescence decay curve are used to characterize the fluorescence properties of phosphors. The experimental results show that XRD test results are in good agreement with the cubic phase of CaF2; SEM study shows that the CaF2Tb3+ phosphors are spherical-like shape and their particle sizes are about 30 nm. The optimal doping amount of substance concentration of Tb3+ in phosphors is 6%. Photoluminescence emission spectra indicate that the CaF2Tb3+ phosphors emit strong green light with 259 nm light excitation. The excellent luminescence properties make CaF2Tb3+ a new promising green phosphors for fluorescent labeling application..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 516002 (2014)
Syntheses and Luminescent Properties of Terbium-Sulfosalicylic Acid-Undecylenic Acid
Li Liping, Zhang Aiqin, Jia Husheng, and Xu Bingshe
The green light fluorescent powder of Tb-sulfosalicylic acid-undecylenic acid used in white light emitting diode (WLED) is synthesized. Infrared (IR) spectra show that the ligands have coordinated with Tb(Ⅲ) ion successfully. Ultraviolet (UV)-vis adsorption spectra demonstate that the absorption of complexes mainly comThe green light fluorescent powder of Tb-sulfosalicylic acid-undecylenic acid used in white light emitting diode (WLED) is synthesized. Infrared (IR) spectra show that the ligands have coordinated with Tb(Ⅲ) ion successfully. Ultraviolet (UV)-vis adsorption spectra demonstate that the absorption of complexes mainly comes from the ligands absorption. Flurescence spectra suggest that the complex emits characteristic green light at 543 nm excited by 365 nm UV light. And this characteristic indicates that the complex can be used as photoluminescent phosphors of UV chips potentially. Thermogravimetric analysis manifests that the decomposition temperature of the complex is near 200 ℃, meeting the requirement of working temperature of WLED well. The fluorescence lifetime of the complex is 1.413 ms and the quantum yield reaches up to 42%. Furthermore, the singlet and triplet energy levels of the ligands are calculated by quantum chemistry, and the luminous mechanism of the complex is explored..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 516003 (2014)
Nonlinear Optics
Properties and Critical Behavior of Fundamental Surface Defect Mode Soliton
Zhu Desheng, Xu Fei, Zhang Liang, Tian Yonghong, and Xu Dahai
Properties of the fundamental surface defect mode soliton have very important applications in all-optical control field. Based on nonlinear Schrdinger equation, properties of the fundamental surface defect mode, which can be supported by semi-infinite lattices with a local defect in Kerr-type nonlinear media, have beeProperties of the fundamental surface defect mode soliton have very important applications in all-optical control field. Based on nonlinear Schrdinger equation, properties of the fundamental surface defect mode, which can be supported by semi-infinite lattices with a local defect in Kerr-type nonlinear media, have been studied in details by employing numerical methods such as image-time method, nonlinear relaxation method and split-step Fourier algorithm. The research results show that the fundamental surface defect mode can only stay in the defect channel when the defect is attractive. However, when the defect is rejective, the fundamental surface defect mode can stay in the defect channel or not. In such a system, there are several critical values of the system parameters, and it is found that whether the fundamental defect mode can locate in the defect or not depends on whether the parameter value is higher or lower than its critical value when other parameters remain unchanged. In terms of physical mechanism, the competition between the optical lattices and nonlinear refractive index induced by optical beam leads to the occurrence of the critical behavior..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 519001 (2014)
Optical Design and Fabrication
Dwell Time Algorithm for Large Aperture Optical Element in Magnetorheological Finishing
Li Longxiang, Deng Weijie, Zhang Binzhi, Bai Yang, Zheng Ligong, and Zhang Xuejun
In order to obtain high precise optical surface by magnetorheological finishing (MRF), an algorithm combined with SBB (Subspace Barzilai and Borwein) and adaptive Tikhonov regulation is proposed to get dwell time distribution based on matrix multiplication. Moreover, double removal functions are introduced to polishingIn order to obtain high precise optical surface by magnetorheological finishing (MRF), an algorithm combined with SBB (Subspace Barzilai and Borwein) and adaptive Tikhonov regulation is proposed to get dwell time distribution based on matrix multiplication. Moreover, double removal functions are introduced to polishing of the circle mirror with spiral path to guarantee the convergence of center area and surface precision of full aperture. Algorithm′s simulation shows that the accuracy of the method mentioned above is the same with traditional Lawson-Hanson method, but the computing rate is much faster than the latter. The example calculation of Φ600 mm circle mirror with main coma surface error presents that the value of peak-valley (PV) value and root mean square (RMS) from 2.712λ and 0.461λ converges to 0.306λ and 0.0199λ (λ=632.8 nm) with the center and full aperture consistent. Therefore, the algorithm in this paper can ensure the convergence accuracy of the surface shape while solving the dwell time distribution effectively and keeping the solution accurate and stable fast. The result provides support to the application of MRF on large aperture optical element..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 522001 (2014)
Design of Compact Athermalizing Uncooled Infrared Optical System
Qu Hemeng, Zhang Xin, Zhang Jizhen, and Wang Lingjie
With rapid growth of uncooled infrared detector technology, uncooled infrared optical systems are widely used. The uncooled infrared optical system must fulfill the requirements of compact size, large relative aperture, high temperature adaptability and stray light suppression ability. A catadioptric optical system witWith rapid growth of uncooled infrared detector technology, uncooled infrared optical systems are widely used. The uncooled infrared optical system must fulfill the requirements of compact size, large relative aperture, high temperature adaptability and stray light suppression ability. A catadioptric optical system with secondary image is adopted to realize the design parameters of 0.55 ratio of total length and focal length and 0.8 F number. In addition, the optical passive compensation method is used to realize an athermalized design in the temperature range of -40 ℃~50 ℃ by matching optical and structural materials properly, and the field stop in the first image can ensure the optical system a high stray light suppression ability. The design result shows that optical system′s modulation transfer function in each field is close to the diffraction limit at different temperatures and the system size is compact. Finally, it is proved that this uncooled infrared optical system can meet environmental requirements of airborne and missile application through the actual imaging experiment at high and low temperatures..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 522003 (2014)
Physical Optics
Characteristic Analysis on Diffraction of Rectangular Optical Waveguide Ey00 Mode
Lin Xiaoming, Li Lianhuang, and Guo Fuyuan
Based on the approximative theory of Marcatili, an approximate mode expression of rectangular optical waveguide Ey00 mode is presented. Based on the angular spectrum principle of plane wave, the expression of diffraction spatial frequency spectra for rectangular optical waveguide Ey00 mode is deduced. The distribution Based on the approximative theory of Marcatili, an approximate mode expression of rectangular optical waveguide Ey00 mode is presented. Based on the angular spectrum principle of plane wave, the expression of diffraction spatial frequency spectra for rectangular optical waveguide Ey00 mode is deduced. The distribution characteristics of diffraction spatial frequency spectra for rectangular optical waveguide Ey00 mode in x axis is discussed. The beam propagation factors M2 of rectangular optical waveguide Ey00 mode in x and y axis are analysed. The spatial frequency half width of rectangular optical waveguide Ey00 mode is numerically analysed by power in the quadrate bucket, and the curve of rectangular optical waveguide Ey00 mode spatial frequency half width defined by power in the quadrate bucket versus normalized frequency is obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 526001 (2014)
Reserach on Fine Structure of Ground-State Energy Levels and the Jahn-Teller Effect of Fe2P2S6 Crystal
Yin Chunhao, Xu Zhenkun, Wu Caiping, Zhang Lei, Jiao Yang, Liu Haishun, and Li Fuqiang
The complete Hamilto matrices of trigonal symmetry 3d4/3d6 electron configuration are derived using Racah′s irreducible tensor operator method in the weak field scheme. The ground-state energy levels and crystal structure of the Fe2+ in Fe2P2S6 crystal are studied and the ground-state energy levels and the zero-field sThe complete Hamilto matrices of trigonal symmetry 3d4/3d6 electron configuration are derived using Racah′s irreducible tensor operator method in the weak field scheme. The ground-state energy levels and crystal structure of the Fe2+ in Fe2P2S6 crystal are studied and the ground-state energy levels and the zero-field splitting of electron paramagnetic resonance of Fe2P2S6 crystal are calculated considering the effects of spin-orbit coupling and spin-spin coupling in ground-state energy levels. The calculated results are in good agreement with the experimental values. Moreover, the effects of spit-orbit coupling, spin-spin coupling and low-spin states 3L on the ground-state energy levels and zero-field splitting are investigated further based on the calculated results and the Jahn-Teller effect of Fe2P2S6 crystal is studied as well..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 526002 (2014)
Flattop Beam Creation Based on Strong Focusing of Circularly Polarized Vortex Beams
Liu Jian, Yang Yanfang, He Ying, Liu Guowei, and Zheng Xiao
Because circularly polarized vortex beam can be characterized as the linear super position of radially polarized and azimuthally polarized components in the cylindrical coordinate, when study the focusing properties of the circularly polarized vortex beam, we must consider radially polarized vector beam with topologicaBecause circularly polarized vortex beam can be characterized as the linear super position of radially polarized and azimuthally polarized components in the cylindrical coordinate, when study the focusing properties of the circularly polarized vortex beam, we must consider radially polarized vector beam with topological nuclei has azimuthal component after focusing and azimuthally polarized vector beam has radial component after focusing. Based on the corrected tightly focusing formula of the circularly polarized vortex beam, we afresh study the tightly focusing properties of the circularly polarized vortex beams with different topological nuclei. The results show that not only the focusing of the single handedness of the circularly polarized vortex beam but also the focusing of superposition of two circularly polarized vortex beams can generate flattop beam. By choosing the proper amplitude ratio, waist radius and the aperture blocking, the half-width of flattop beam can be changed effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 526003 (2014)
Quantum Optics
Experimental Study of Quantum Noise Characteristics of the Probe Field in Electromagnetically Induced Transparency Medium
Wang Fang, Yu Xudong, Meng Zengming, and Zhang Jing
Balanced homodyne detection is used to measure the quadrature amplitude and quadrature phase noise spectra of the probe field in electromagnetically induced transparency (EIT) medium. Through adjusting the voltage of the piezoelectric ceramic transducer, the optical path of the local light is changed so that the relatiBalanced homodyne detection is used to measure the quadrature amplitude and quadrature phase noise spectra of the probe field in electromagnetically induced transparency (EIT) medium. Through adjusting the voltage of the piezoelectric ceramic transducer, the optical path of the local light is changed so that the relative phase of the local light and the probe light in the balanced homodyne detection is adjusted. Then the noise components of the probe light with different phases are measured. It is observed that the coupling of the probe light and the coupling light leads to the increase of the noise of the probe light in eletromagnetically induced transparency medium. It is found that the induced extra noises of different quadrature components of the probe field are different for different detuning values of the coupling light. Simultaneously, the relationship between the noise of the probe field, the power of the coupling light and analysis frequency is obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 527001 (2014)
Research on Quantum Statistic Properties of Photon Number in Pulse Mode Nonlinear Frequency Up-Conversion
Li Xiongjie, Ding Jingxin, Tang Ruikai, Zhou Qian, Shi Xueshun, Yang Lechen, Zhao Kun, Pan Haifeng, and Wu E
Frequency conversion technique attracts increasing attention in the applications in quantum optics. While the single-photon level pulse mode frequency conversion′s quantum photon number statistics and quantum transmission theory still need to be improved. The photon number statistical distribution and quantum state traFrequency conversion technique attracts increasing attention in the applications in quantum optics. While the single-photon level pulse mode frequency conversion′s quantum photon number statistics and quantum transmission theory still need to be improved. The photon number statistical distribution and quantum state transference in the interaction picture are discussed by three-wave mixing equation of the nonlinear frequency up-conversion, where the signal photons and pump light field are either continuous wave or Gaussian-shaped pulse mode. The results show that in different modes of signal photons and pump light field interaction, the photon number statistical distribution can be transferred and remain the same as the incident signal photon in the nonlinear frequency conversion process. These results have important reference value for the development of new quantum up-conversion devices and quantum control devices which are based on quantum frequency conversion..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 527002 (2014)
Remote Sensing and Sensors
Principle of Self-Interferometric Synthetic Aperture Ladar for 3D Imaging
Liu Liren
On the basis of down-looking synthetic aperture ladar (DL-SAL), a kind of self-interferometric SAL for 3D topographic relief imaging is proposed in this paper. Firstly, the forward-scanning and backward-scanning cylinder lenses for imaging along the orthogonal direction of travel are biased in their positions, it thus On the basis of down-looking synthetic aperture ladar (DL-SAL), a kind of self-interferometric SAL for 3D topographic relief imaging is proposed in this paper. Firstly, the forward-scanning and backward-scanning cylinder lenses for imaging along the orthogonal direction of travel are biased in their positions, it thus introduces a shifted spectrum image with a linear phase term. Then pair of a forward-scanning resulted focused image and the next backward-scanning resulted image are coherently added, therefore a self-interference between the two images occurs. The flat fringes from this self-interference can be obliquely projected to a target plane, so that a subtly rippled interferogram containing the target height information can be observed. Finally, by using the unwrapping algorithm, a contour mapping representing the surface profile will be achieved. This SAL including a transmitter and a receiver realites the 3D imaging by a one-pass interferometry. The features are simple in construction and effective in principle. Moreover, the phase errors from the atmospheric turbulence can be automatically compensated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 528001 (2014)
Development of BRDF Absolute Measuring Device
Li Junlin, Zhang Liming, Chen Hongyao, Si Xiaolong, Wang Jixiang, Yang Baoyun, and Shen Zhengguo
The method of on-board calibration based on sun-diffuse panel panel plus radiometer for stability monitoring can improve the level of quantification of remote sensing data, and the BRDF calibration accuracy of diffuse panel is the key of high-precision on-board calibration, and the BRDF absolute measurement can realizeThe method of on-board calibration based on sun-diffuse panel panel plus radiometer for stability monitoring can improve the level of quantification of remote sensing data, and the BRDF calibration accuracy of diffuse panel is the key of high-precision on-board calibration, and the BRDF absolute measurement can realize high-precision calibration of the diffuse panel. In order to solve the key technology of high-precision BRDF absolute measurement, we design a high-brightness, high-stability and high-uniformity integrating sphere as the lamp source; using a monochromator and a single detector to detect the incident and reflected radiance signals with large dynamic range accurately, moreover using a lock-in amplifier to amplify and acquire the signals; using high-precision six-axis robot and hollow rotary indexing table orientate sample diffuse panel with three-dimensional rotation and translation and lamp source with one-dimensional rotation separately to construct BRDF absolute measuring geometry with high-precision, non-blocking and speediness. The device can realize omnidirectional BRDF measurements except for that out of plane, and measurable angle range is: azimuthal angle is 0°~360°, and zenith angle is 0°~75°. Currently measurable spectral range is 250~1700 nm. The uncertainty degree of this device can be less than 1%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 528002 (2014)
Spectroscopy
Correction of Detector Response Error for Hyperspectral Spatial Heterodyne Interferometer
Li Zhiwei, Xiong Wei, Shi Hailiang, Wang Xianhua, Ye Hanhan, Wei Qiuye, and Qiao Yanli
The spatial heterodyne spectrometer used for high precision atmospheric CO2 remote sensing adopts array detector to collect the two-dimensional interferogram at the same time. According to the response nonlinearity and non-uniformity existing in array detector simultaneously, the influence on the interferogram and the The spatial heterodyne spectrometer used for high precision atmospheric CO2 remote sensing adopts array detector to collect the two-dimensional interferogram at the same time. According to the response nonlinearity and non-uniformity existing in array detector simultaneously, the influence on the interferogram and the recovered spectrum is analyzed respectively. It is pointed out that, at the same detector non-uniform noise, the higher the spectral resolution, the higher noise in recovered spectrum is. The nonlinearity not only impacts the effective spectral range, but also brings nonzero value below the spectral cutoff frequency. A method of correction nonlinearity by several uniform radiances and non-uniformity by a single uniform radiance is reported. The experiments are fulfilled, and the response non-uniformity improves from 4.04% to 0.14%. The recovered spectrum from the corrected interferogram is smooth due to the non-uniformity noise reduction greatly, and the data out of the spectrum cutoff frequency have zero values for correction the response nonlinearity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 530001 (2014)
Laser Frequency Stabilization of 1560 nm Laser after Frequency Doubling to 780 nm with a Waveguide: Radio-Frequency Frequency-Modulation Spectroscopy versus Modulation Transfer Spectroscopy with Rb Atoms
Han Yashuai, Wen Xin, Bai Jiandong, He Jun, and Wang Junmin
By efficient frequency doubling of 1560 nm distributed feed back laser with a MgO:PPLN waveguide, the laser frequency is locked to the D2 hyperfine transition of 87Rb atoms via radio-frequency frequency modulation spectroscopy (RF-FMS) and modulation transfer spectroscopy (MTS). The theories, spectra and frequency lockBy efficient frequency doubling of 1560 nm distributed feed back laser with a MgO:PPLN waveguide, the laser frequency is locked to the D2 hyperfine transition of 87Rb atoms via radio-frequency frequency modulation spectroscopy (RF-FMS) and modulation transfer spectroscopy (MTS). The theories, spectra and frequency locking results of the two schemes are compared. The root mean squares of frequency fluctuation with feedback using the two schemes are ±135 kHz and ±85 kHz, respectively, while it is 8~10 MHz for free running. This is owing to the better signal-to-noise ratio and completely no background for MTS. Utilizing MTS, a compact, robust 1.5 μm laser system for fiber-optic communication application is built..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 530002 (2014)
Optimization Modeling for Experimental Parameters of Laser-Induced Breakdown Spectroscopy by Quadratic Regression Orthogonal Design
Sun Lanxiang, Xin Yong, Cong Zhibo, Li Yang, and Qi Lifeng
Laser-induced breakdown spectroscopy (LIBS) offers a simple and fast tool for multi-element simultaneous analysis. For optimizing experimental factors in LIBS multi-element simultaneous analysis, an objective function, named “integrated signal-to-background ratio (ISBR)”, is proposed. The coupling influences of the lasLaser-induced breakdown spectroscopy (LIBS) offers a simple and fast tool for multi-element simultaneous analysis. For optimizing experimental factors in LIBS multi-element simultaneous analysis, an objective function, named “integrated signal-to-background ratio (ISBR)”, is proposed. The coupling influences of the laser energy, measuring time delay, distance between lens and samples, and integration time on the objective function are modeled based on the quadratic regression orthogonal design (QROD). Experimental results indicate that the objective function can contain multiple spectral properties and can provide a standard for the selection of experimental conditions in multi-element analysis. By the multi-factor model built through the QROD, more optimal experimental parameters can be obtained and less experimental numbers are needed than by the single factor experiments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 530003 (2014)
Thin Films
Simulation Model of Surface Carbon Deposition Contamination Under Extreme Ultraviolet Radiation
Wang Xun, Jin Chunshui, Kuang Shangqi, Yu Bo, and Jin Fangyuan
Extreme ultraviolet lithography (EUVL) is one of the most promising candidates for next generation lithography to achieve 22 nm technology node. It takes of extreme ultraviolet (EUV) at 13.5 nm. With this wavelength, all the exposure equipments must be reflective. Whereas, for the extreme ultraviolet irradiated opticalExtreme ultraviolet lithography (EUVL) is one of the most promising candidates for next generation lithography to achieve 22 nm technology node. It takes of extreme ultraviolet (EUV) at 13.5 nm. With this wavelength, all the exposure equipments must be reflective. Whereas, for the extreme ultraviolet irradiated optical elements, the two main mechanisms that reduce reflectivity of EUV reflective film are carbonization and oxidation of the film surface. Researching the mechanism of carbon deposited layer with surface molecule kinetic theory of EUV optical devices to find an effective way for inhibiting the deposition of pollution. We investigate the validity of models and assumptions by researching on carbon pollution layer model, indirectly proving the Boller′s theory “secondary electron induced decomposition is the main deposition process”. Present preliminary numerical results on the dependence of contamination rates on key parameters with the iterative method, and suggest a band of 50~80 nm where will produce a higher contamination rate..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 531001 (2014)
Optical Constants and Properties of Dual-Ion-Beam Sputtering Ta2O5/SiO2 Thin Film by Spectroscopy
Shang Peng, Xiong Shengming, Li Linghui, and Tian Dong
Single Ta2O5 and double layer Ta2O5/SiO2 films are deposited on Si and fused silica substrates by dual-ion-beam sputtering. With the Cauchy dispersion model, the optical constants of Ta2O5 and SiO2 thin films are obtained by fitting the transmission spectra of single Ta2O5 and double layer Ta2O5/SiO2 films using the coSingle Ta2O5 and double layer Ta2O5/SiO2 films are deposited on Si and fused silica substrates by dual-ion-beam sputtering. With the Cauchy dispersion model, the optical constants of Ta2O5 and SiO2 thin films are obtained by fitting the transmission spectra of single Ta2O5 and double layer Ta2O5/SiO2 films using the combination of simplex and genetic algorithm (GA) optimization method. It shows that the results calculated by fitting the whole optical spectra are well consistent with the measuring values. The refractive index error and thickness error of single layer Ta2O5 film are less than 0.001 nm and 1 nm, respectively. In the case of double layer Ta2O5/SiO2 films，the maximum refractive index error and thickness error are in the range of 0.004 nm and 2.5 nm, respectively. In addition, the deposited double layer Ta2O5/SiO2 thin films are treated at 400 ℃ in air. The changes of microstructure, surface morphology and optical properties of the Ta2O5/SiO2 films are investigated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 531002 (2014)
Vision, Color, and Visual Optics
Pedestrian Contour Extraction and Its Recognition Using Stereovision and Snake Models
Liu Shumin, Huang Yingping, and Zhang Renjie
Accurate extraction of object contour from complex and dynamic traffic images is crucial for intelligent vehicles, and plays an important role for pedestrian protection. Snake Models are widely employed to object contour outomatic extraction. Presented here is a novel approach for pedestrian recognition by combining stAccurate extraction of object contour from complex and dynamic traffic images is crucial for intelligent vehicles, and plays an important role for pedestrian protection. Snake Models are widely employed to object contour outomatic extraction. Presented here is a novel approach for pedestrian recognition by combining stereovision with Snake models. Object segmentation based on dense disparity map is used to locate and break up regions which contains potential pedestrians. Furthermore, edge-indexed stereo matching algorithm is employed to obtain the initial edges of the targets of the regions in order to facilitate object contour extraction in the later stage. Snake models are adopted to extract complete contour curves of the targets. Contour factors derived from the contour curves and target elevation are used to verify the targets i.e. pedestrian recognition. To overcome the limitations of Snake models, distance potential models are modified to immunize from noise and to make the model converge into the boundary concavity. The approach presented here is tested on substantial traffic images and the corresponding results prove the efficiency of the approach..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 5, 533001 (2014)
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