Contents
2011
Volume: 32 Issue 1
51 Article(s)
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Atmospheric Optics and Oceanic Optics
Study of Backward Optical Detection Method for Ship Wake Bubbles
Han Biao, Liu Jifang, Liu Kunlun, Wang Xu, Zhou Shaojie, and Shi Shunxiang
In order to search a backward optical method for ship wake detection, the influence of wake bubbles on backscattering signal of laser pulse in water is studied. Firstly, based on Fournier Forand volume scattering function, the influence of short-distance bubbles on laser pulse′s backscattering signal in water is analyzIn order to search a backward optical method for ship wake detection, the influence of wake bubbles on backscattering signal of laser pulse in water is studied. Firstly, based on Fournier Forand volume scattering function, the influence of short-distance bubbles on laser pulse′s backscattering signal in water is analyzed. Secondly, using blue-green laser pulse as light source, the influence of imitated bubbles on laser pulse′s backscattering signal in water is studied experimentally. The results show that, because of wake bubbles, back scattering signal′s leading edge moves left, and its trailing edge moves right. Moreover, the broadering of its width, enhancement of its energy and the increase of its peakvalue also happen, and its position moves left in time-domain. Finally, according to the result, a backward detection method for ship wake bubbles is presented on the basis of the characteristic′s variation of laser pulse′s backscattering signal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 101001 (2012)
Scattering and Polarization Characteristics of Dust Aerosol Particles
Hao Zengzhou, Gong Fang, Pan Delu, and Huang Haiqing
Based on Mie scattering theory, the single scattering albedo and the phase-matrix function of dust aerosol particles during wavelength of 0.2~40 μm for solar radiation and earth-atmosphere long-wave radiation are calculated with the lognormal distribution function to describe the dust particles size distribution. The sBased on Mie scattering theory, the single scattering albedo and the phase-matrix function of dust aerosol particles during wavelength of 0.2~40 μm for solar radiation and earth-atmosphere long-wave radiation are calculated with the lognormal distribution function to describe the dust particles size distribution. The scattering intensity and polarization characteristics of light scattered by dust aerosol particles are studied at different relative humidity conditions. The results show that, the single scattering albedo has an evident change with the incident wavelength; the variation trend is identical at different relative humidity conditions; within the visible and near-infrared band, the single scattering albedo increases with the increasing relative humidity, it is very close to 1 at relative humidity of 95%; within the thermal infrared band greater than 10 μm, the single scattering albedo decreases with the increasing relative humidity and it has strong ability to absorb radiation. The scattering intensity has less effect on relative humidity and shows a trend of decreasing firstly and then increasing with the increasing scattering angle, the increasing tendency decreases with the increasing wavelength; for the linear and circular polarization of scattered radiation, the change with the scattering angle and relative humidity has different properties at different bands; in the forward and backward scattering directions, it only produces the circular polarization by dust aerosol particles, when it is assumed that incident light is right hand circularly polarized. Polarization properties of scattered radiation and their differences with humidity mainly change in the backward scattering region, where it is as an arched form. The scattering angle for peak point is different at different relative humidities and the peak position drifts to the larger scattering angle with the decreasing relative humidity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 101002 (2012)
Numerical Simulation and Characteristics Analysis of Laser Self-Mixing Interference Measurement of Atmospheric Particle Parameters
Wang Xiuli, Gui Huaqiao, Lu Yihuai, Liu Jianguo, Wang Jie, and Wu Dexia
The theoretical expressions describing the self-mixing interference laser frequency, output power, and linewidth under the weak feedback of atmospheric particles are deduced based on the Mie scattering theory, the three-mirror theory and the steady-state equations of laser. The theory model of self-mixing effect feedbaThe theoretical expressions describing the self-mixing interference laser frequency, output power, and linewidth under the weak feedback of atmospheric particles are deduced based on the Mie scattering theory, the three-mirror theory and the steady-state equations of laser. The theory model of self-mixing effect feedback from atmospheric particles is established. And the relationship between the self-mixing signals and the physical parameters of atmospheric particles is analyzed in detail. The result shows that in a certain particle size range, the laser self-mixing signal intensity increases with the particle size and then decreases. With the increase of the real part and decrease of the imaginary part in atmospheric particle complex refractive index, the location of the external feedback strength peak value gradually moves to larger particle size. The amplitude of self-mixing signals is exponential decay with the increase of the external feedback cavity; the fluctuation frequency of the laser intensity is linearly related to the velocity of atmospheric particles. These conclusions offer a theoretical guidance to study optical sensing applications of atmospheric particles physical parameters by using the laser self-mixing technology..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 101003 (2012)
Spectral Irradiance Calibration Research of the Solar Backscattered Ultraviolet Spectroradiometer in Air/Vacuum Conditions
Yang Xiaohu, Wang Shurong, and Huang Yu
A group of improving methods for the on-ground calibration of solar backscattered ultraviolet spectroradiometer (SBUS) has been put forward to increase its precision of on-board detection and data inversion. The full-waveband radiometric calibration in vacuum, which can attain correspondence match of condition between A group of improving methods for the on-ground calibration of solar backscattered ultraviolet spectroradiometer (SBUS) has been put forward to increase its precision of on-board detection and data inversion. The full-waveband radiometric calibration in vacuum, which can attain correspondence match of condition between on-ground calibration and on-board detection, is the first item. A spectral irradiance responsibility comparing measurement setup is built and the spectral irradiance response of SBUS to a same source is measured in air and vacuum, respectively. The result shows a 0.8% relative deviation between air and vacuum in 250~300 nm and a wavelength dependent deviation, among which the maximum is a little more than 15%, in 300~400 nm. The individual uncertainty caused by calibration condition of SBUS in vacuum is 1.8% smaller than that in air. After theoretical analysis and confirmatory testing, it is found that the spectral reflectivity of Al+MgF2 coating of SBUS reflecting element would be different in air and in vacuum, which proves the necessity of SBUS calibration in vacuum condition..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 101004 (2012)
Diffraction and Gratings
Parameter Design of Parallax Barrier Based on Color Moiré Fringe in Three-Dimensional Displays
Kong Lingsheng, Jin Guang, Cai Sheng, Xu Kai, Wang Tiancong, and Zhong Xing
In order to confirm appropriate parameters of parallax barrier (PB), a parameter design of PB based on a color Moiré condition in autostereoscopic displays is proposed. Liquid crystal display (LCD) and PB are approximated as the two corresponding binary gratings. Special radial grating is considered as the equivalIn order to confirm appropriate parameters of parallax barrier (PB), a parameter design of PB based on a color Moiré condition in autostereoscopic displays is proposed. Liquid crystal display (LCD) and PB are approximated as the two corresponding binary gratings. Special radial grating is considered as the equivalent model of PB with varying periods and angles. Superposition of the equivalent grating for display device and special radial grating can be analyzed by indicial equations method and Fourier theory. Different predominant low-frequency terms in case of different period of PB can be confirmed. The Moiré-fringe intensity profile in all cases can be obtained by partial sum extraction in Fourier theory. Optimal period and corresponding angle of PB are obtained. Experiment result shows that the autostereoscopic displays have almost invisible Moiré patterns and show good autostereoscopic image..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 105001 (2012)
Fiber Optics and Optical Communications
An Elliptical-Core Hollow Fiber with High Second-Order Nonlinearity
Tian Fengjun, Yuan Libo, Liu Zhihai, and Bo Fusen
A novel elliptical-core hollow fiber (ECHF) with high second-order nonlinearity (SON) applied in phase modulator is proposed and fabricated. A large linear electro-optic phase shift observed in the fiber has been induced by thermal poling at about 300 ℃ for 30 min with an electric field larger than 1×108 V/m and aA novel elliptical-core hollow fiber (ECHF) with high second-order nonlinearity (SON) applied in phase modulator is proposed and fabricated. A large linear electro-optic phase shift observed in the fiber has been induced by thermal poling at about 300 ℃ for 30 min with an electric field larger than 1×108 V/m and a 9-cm-length electrode. Based on ECHF an in-fiber Mach-Zehnder interferometer (MZI) is constructed, movement of interference fringe to estimate phase shift is observed. As high as 1.16 pm/V SON coefficient and 0.52 pm/V linear electro-optic (EO) coefficient are obtained. This technology is simple and versatile that can be utilized to fabricate high EO coefficient devices, which can decrease fabrication cost, and realize higher integration level of all fiber devices..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 106001 (2012)
Effect of Aberration on Performance of the Bit Error Rate in an Inter-Satellite Coherent Optical Communication Receiving System
Liu Hongzhan, Ji Yuefeng, and Liu Liren
Based on the space optical communication link equation, it is given in detail that the signal-to-noise ratio (SNR) equations for the inter-satellite coherent optical communication receiving system (ISCOCRS) with different aberrations. With communication distance for 60000 km, transmission rate of 2 Gb/s binary phase shBased on the space optical communication link equation, it is given in detail that the signal-to-noise ratio (SNR) equations for the inter-satellite coherent optical communication receiving system (ISCOCRS) with different aberrations. With communication distance for 60000 km, transmission rate of 2 Gb/s binary phase shift keying (2PSK) homodyne geosynchronous orbit receiving system as an example, through numerical simulation, the effect of the tilt, defocusing, coma and astigmatism aberrations on the bit error ratio(BER) of the ISCOCRS is compared systematically. The simulation results show that effect of the tilt aberration is the BER is more seriously than the astigmatism when the different aberrations influence the ISCOCRS individually, at the same time, the different aberrations can be partly corrected by another when they effect mutually, Which leads to the lower BER. With the BER more than 10-6 as standard, through adjusting the tilt, the coma can be partly corrected when the normalized coma is more than 1.00, and adjusting the defocusing can partly correct the astigmatism when the normalized astigmatism is more than 0.53. Therefore, the aberrations′ influence should be overlooked in the process of designing the ISCOCRS. These results provide some theoretic basis for the ISCOCRS..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 106002 (2012)
Experimental Investigation on Antinoise Technique of Interferometric Fiber Fabry-Perot Sensor System
Niu Siliang, Liao Yi, Rao Wei, and Hu Yongming
In interferometric fiber Fabry-Perot (FFP) sensor systems, environmental disturbances in interrogation interferometers are a dominant source of noise. In a fiber Bragg grating defined FFP sensor system, the antinoise techniques utilizing reference sensor and reference wavelength are compared with each other. Signal-to-In interferometric fiber Fabry-Perot (FFP) sensor systems, environmental disturbances in interrogation interferometers are a dominant source of noise. In a fiber Bragg grating defined FFP sensor system, the antinoise techniques utilizing reference sensor and reference wavelength are compared with each other. Signal-to-noise ratio improvements of 40 dB have been achieved experimentally for both single-frequency and broadband disturbances. Moreover, because of the lower noise level of the reference fiber laser with a narrow linewidth, the differential result of the reference wavelength approach exhibits a better antinoise effect..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 106003 (2012)
Joint Phase Equalization in Optical Orthogonal Frequency Division Multiplexing System
Gao Lina, Liu Jianfei, Zeng Xiangye, and Jiang Weihu
The combination of orthogonal frequency division multiplexing (OFDM) technology, coherent receiver and digital singal processing (DSP) is one of the ideal models in long-haul communication. However, optical OFDM receiver is sensitive to phase noise, so it is necessary to compensate phase noise for optical OFDM systems.The combination of orthogonal frequency division multiplexing (OFDM) technology, coherent receiver and digital singal processing (DSP) is one of the ideal models in long-haul communication. However, optical OFDM receiver is sensitive to phase noise, so it is necessary to compensate phase noise for optical OFDM systems. A joint phase equalization solution to optical OFDM system based on orthogonal wavelet transform is proposed. In this method, block pilots are periodically inserted into the frame of OFDM signals. At receiver, the phase rotations of pilots are extracted to eliminate common phase difference of each subcarrier. Then, an adaptive equalization is applied to eliminate the phase error inside each subcarrier. Simulation results demonstrate that the proposed method is effective for 100 Gb/s optical binary translation quadrature amplitude modulation (4QAM) OFDM system in which data transmitted over 1000 km with G.652 fiber..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 106004 (2012)
Low-Power Laser Jamming Techniques to Free Space Optical System
Chen Jing, Xue Haizhong, Liu Xuewen, Wei Longchao, and Zhang Fangpei
The intensity modulation direct detection (IM/DD) is widely used for the free space optical (FSO) system currently. In order to explore the most effective and the most practical way to jam the FSO systems, the principle and efficiency of how the low power laser jams the FSO system is researched by using theoretical anaThe intensity modulation direct detection (IM/DD) is widely used for the free space optical (FSO) system currently. In order to explore the most effective and the most practical way to jam the FSO systems, the principle and efficiency of how the low power laser jams the FSO system is researched by using theoretical analysis, simulation and experiment. The feasibility of low-power laser jamming is validated. The jamming phenomenon is mainly manifested as bit error rate increases. At the same time, different principles and phenomena affect by different repetition rates, power and duty cycle of jamming laser on wireless laser communication systems with different communication systems, rates, transmitting power are studied. Because of their different clock systems, synchronous and asynchronous communications have different principles and phenomena. Synchronous communication mainly occurs in the "bit interference" and "clock recovery interference", asynchronous communication system mainly occurs "start bit interference" and "data bit interference." Asynchronous communication that has simple frame structure and coding relatively from synchronous communication can be influenced more easily and serious..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 106005 (2012)
Fourier Optics and Signal Processing
Optical Correlation Recognition of the Moving Target in Cluttered Background
Zhang Su, and Wang Wensheng
In the application of achieving the correlation recognition of moving target with hybrid optoelectronic joint transform correlator (HOJTC), the differences resulting from the movement between the target and the template and the cluttered background influence the correlation ratio of the correlator. A combined method ofIn the application of achieving the correlation recognition of moving target with hybrid optoelectronic joint transform correlator (HOJTC), the differences resulting from the movement between the target and the template and the cluttered background influence the correlation ratio of the correlator. A combined method of wavelet multi-scale edge extraction which uses the first order derivative of Gaussian function and edge processing with morphological dilation is applied. This method can fully use the wavelet multi-scale characteristics. After extracting the edge, the noise can be suppressed and more details can be retained. It can improve the detection efficiency of the moving target in cluttered background apparently. The optical correlation experiments on a low contrast and small moving target show that this method can enhance the brightness of the correlation peaks and verify that the algorithm is feasible to the moving target recognition in cluttered background..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 107001 (2012)
Prototype of an Optical Sampling Oscilloscope with Subpicosecond Temporal Resolution
Liu Yuanshan, Zhang Jianguo, Tang Dingkang, and Zhao Wei
Low timing-jitter, “σ”-type passively mode-locked fiber laser is used as a high-performance optical sampling pulse source, of which the operation stability is high and the repetition frequency is tunable. Then the generated sequence of ultrashort optical sampling pulses is launched together with a 80 Gb/s optical pulseLow timing-jitter, “σ”-type passively mode-locked fiber laser is used as a high-performance optical sampling pulse source, of which the operation stability is high and the repetition frequency is tunable. Then the generated sequence of ultrashort optical sampling pulses is launched together with a 80 Gb/s optical pulse signal under test into a 100 m-long highly nonlinear fiber (HNLF). The all-optical sampling of an optical signal under test is realized by utilizing the four-wave mixing (FWM) in a HNLF. Consequently, the waveform of a 80 Gb/s optical pulse signal with RZ format is precisely reproduced by a computer and is displayed on its screen by employing our developed software for digital signal processing and computer image processing, respectively. Moreover, the optical sampling oscilloscope prototype is used to measure the pulse waveform and pulse width at the output of a commercially available, actively mode-locked semiconductor laser which produces optical pulses of 1.8 ps width (measured by an autocorrelator) at the 10 GHz repetition frequency. In the experiment, the pulse width measured by this oscilloscope prototype system is 2.0 ps. It is clearly shown that our developed optical sampling oscilloscope prototype has a temporal resolution better than 900 fs..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 107002 (2012)
Study of Digital Spectrometer Based on Change Coupled Device
Liu Dongmei, Xia Rihui, Pan Yonggang, Shen Yi, and He Xin
Spectrometer is one of the most important optical instruments. A digital spectrum analysis system based on change coupled device (CCD) is set up. The optical system, CCD, data acquisition board and spectrum analysis software are integrated to implement the digitization, automation, miniaturization and portability of thSpectrometer is one of the most important optical instruments. A digital spectrum analysis system based on change coupled device (CCD) is set up. The optical system, CCD, data acquisition board and spectrum analysis software are integrated to implement the digitization, automation, miniaturization and portability of the system. Spectrum analysis software is developed to realize the function of collecting, analyzing, displaying, peak-seeking, calibration and storage of spectral signal. Spectrum analysis library (SAL) is designed, which greatly simplifies the procedure of software development and increases software protability. The digital spectrometer is calibrated by standard mercury lamp and the software is verified by the laser test. The system is mainly used for remote-site real-time detection of military targets, at the same time, it can be considered for civil use. The experimental results show that the digital spectrum analyzer has a good accuracy and repeatability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 107003 (2012)
Imaging Systems
Fast Detection of Sea Line Based on the Visible Characteristics of Marine Images
Zeng Wenjing, Wan Lei, Zhang Tiedong, and Xu Yuru
A feasible method combining the characteristics of marine visible image is proposed to detect sea-line in the sequential images from surface vehicle. It is not only appropriate for sea-sky background but also for offshore background. The complexity of sub-images and the average gray difference of their up and down neigA feasible method combining the characteristics of marine visible image is proposed to detect sea-line in the sequential images from surface vehicle. It is not only appropriate for sea-sky background but also for offshore background. The complexity of sub-images and the average gray difference of their up and down neighborhoods are measured to predict the sea-line region and the consequent processing of images without the existent of sea-line region is given up. Since the sea-line is the longest line with best continuity in the whole nature vision, improved Canny edge detection with surround texture suppression is applied to extract the contour of the object ready for line detection. Weighted vote in Hough transforming is introduced to pick the right line which is horizontal or tilted. The experimental results prove that this method can locate the sea-line region fast and obtain the binary image including the necessary information and attenuating meaningless information. Sea line can be found precisely in the contour edge. It is robust and real-time and is competent for real task where the correct sea-line location is needed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 111001 (2012)
Liquid Crystal Adaptive Optics System for Retinal Imaging Operated on Open-Loop and Double-Pulse Mode
Kong Ningning, Li Dayu, Xia Mingliang, Qi Yue, and Xuan Li
Using the liquid crystal spatial light modulator as the wavefront compensator, an open-loop adaptive optics system for retinal imaging is developed. Compared with the closed-loop liquid crystal adaptive optics system, the energy efficiency is doubled. The fundus is illuminated twice by two laser pulses throughout a sinUsing the liquid crystal spatial light modulator as the wavefront compensator, an open-loop adaptive optics system for retinal imaging is developed. Compared with the closed-loop liquid crystal adaptive optics system, the energy efficiency is doubled. The fundus is illuminated twice by two laser pulses throughout a single correction loop, which will be much safer for the human eye. A modified mechanical shutter is incorporated in the illumination channel to change the imaging field, and the field of view is thus increased from 0.8° to 1.7°. The timing sequence is optimized, and the continuous correction is performed. Meanwhile, the imaging camera is adjusted to achieve the best image plane. The residual wavefront error after open-loop correction is approximately equal to 0.09λ, and the Strehl ratio is bigger than 0.70. It is a nearly diffraction limited system. The clear photoreceptor images are obtained through open-loop correction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 111002 (2012)
Instrumentation, Measurement and Metrology
A New Correction Algorithm for Diffuse Irradiance Measured with Rotating Shadow-Band Pyranometer Based on Support Vector Regression
Chong Wei, Sha Yizhuo, Xing Hongyan, and Lü Wenhua
Through comparson of the numeric difference between diffuse irradiance measured with rotating shadow-band pyranometer (RSP) and standard reference pyranometer, the influence of meteorological elements like global irradiance, ambient temperature, relative humidity and solar spectrum, etc. on measurement errors of diffusThrough comparson of the numeric difference between diffuse irradiance measured with rotating shadow-band pyranometer (RSP) and standard reference pyranometer, the influence of meteorological elements like global irradiance, ambient temperature, relative humidity and solar spectrum, etc. on measurement errors of diffuse irradiance measured with RSP is analyzed, based on the analysis, a new algorithm of correcting diffuse irradiance measured with RSP is proposed. The algorithm constructs an error modifier prediction model based on support vector regression (SVR) theory first, and then diffuse correction algorithm of RSP can be derived from mentioned prediction model. Applying the correction algorithm to the diffuse irradiance data measured by Solar Radiation Research Laboratory and Lowry Range Solar Station, mean deviaiton and root mean square error of the two stations′ data after correction decrease to -0.2 W/m2, 3.3 W/m2 and 1.9 W/m2, 8.5 W/m2, which indicates that the algorithm is effective and applicative. Meanwhile, compared with Vignola correction algorithm and Vignola and Augustyn (VA) correction algorithm, the algorithm presented can avoid respective undercorrection and overcorrection of similar correction algorithm effectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 112001 (2012)
Using a Laser Tracker to Measure the Surface of Off-Axis Aspheric Mirror During Grinding
Li Jie, Wu Fan, Wu Shibin, Kuang Long, and Lin Changqing
In order to measure the off-axis aspheric surface before optical testing, method of using a laser tracker to measure the surface shape is investigated. The procedure and data processing method of the measurement are introduced. Using a commercial laser tracker, an off-axis parabolic mirror with an aperture of 150 mm, rIn order to measure the off-axis aspheric surface before optical testing, method of using a laser tracker to measure the surface shape is investigated. The procedure and data processing method of the measurement are introduced. Using a commercial laser tracker, an off-axis parabolic mirror with an aperture of 150 mm, radius of curvature of 1200 mm, and off-axis distance of 240 mm is measured. The measurement uncertainty is analyzed and measurement result is compared with that of coordinate measuring machine. The result shows a peak-to-valley value consistency better than 1 μm. The method is easy operation and flexible, and meets the measurement requirements of the off-axis aspheric mirror surface before polishing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 112002 (2012)
Location Error Compensation Algorithm for Measuring Optical System Wave Front by Sub-Aperture Stitching
Wang Lihua, Wu Shibin, Ren Ge, Tan Yi, and Yang Wei
In order to realize sub-aperture stitching measurement of large optical wavfront, sub-aperture location compensation algorithm is introduced and the ability to compensate the mechanical location error is analyzed. Based on the aperture of the tested optical system and the sub-aperture, the layout of the sub-aperture isIn order to realize sub-aperture stitching measurement of large optical wavfront, sub-aperture location compensation algorithm is introduced and the ability to compensate the mechanical location error is analyzed. Based on the aperture of the tested optical system and the sub-aperture, the layout of the sub-aperture is calculated. In the range of the mechanical location error, stitching the sub-aperture to get the location compensation coefficients and the adjusting error coefficients, the full aperture of the tested wavefront is got and the large optical wavefront is tested. The feasiblility of the algorithm is tested by the simulation, and the wavefront of the optical system with aperture of 200 nm is tested when the mechanical translation precision is 1 mm and rotation precision is 0.5°. The result indicates the stability of the algorithm and can effectively compensate the sub-aperturre location error caused by the mechanical, which can reduce the high requirement of the mechanical platform..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 112003 (2012)
Research on Absolute Calibration of Photodetector Quantum-Efficiency Using Entangled Photons
Lü Liang, Zhang Yinchao, and Lin Yandong
In response to the new definition of "Candela", the research on measurement of photodetector quantum efficiency (QE) with entangled photon method is carried out, and a complete QE measurement setup is established. From a Type-I phase match BBO crystal pumped by a 351.1 nm CW laser, the correlated photons are In response to the new definition of "Candela", the research on measurement of photodetector quantum efficiency (QE) with entangled photon method is carried out, and a complete QE measurement setup is established. From a Type-I phase match BBO crystal pumped by a 351.1 nm CW laser, the correlated photons are generated, potomultiplier tube (PMT) QE is calibrated at 702.2 nm and 788.7 nm based on the coincidence count system which is realized with a dual-channel gated photon counter. At the same time, the key factors which influence the QE measurement are analyzed, including single-photon pulse acquisition, noise suppression and extraction, time related character about coincidence, accidental coincidence counts, dark counts, transmittance of optics. In the end, the measurement uncertainty of QE at the two wavelengths is less than 0.7%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 112004 (2012)
Grouped Approach Algorithm for Mapping Camera Calibration Based on Method of Exact Measuring Angle
Yuan Guoqin, Ding Yalin, Hui Shouwen, Liu Liguo, and Yu Chunfeng
Toward the problems of theoretical error and the distribution status of the observed which can influence on camera calibration accuracy, a grouped approach algorithm based on exact measuring angle method is proposed. The proposed algorithm is composed of two parts: the method of adjusting the zero point of precise rotaToward the problems of theoretical error and the distribution status of the observed which can influence on camera calibration accuracy, a grouped approach algorithm based on exact measuring angle method is proposed. The proposed algorithm is composed of two parts: the method of adjusting the zero point of precise rotating platform is put forward to reduce the theoretical error, and the method of weighted theory is used to approach group data processing to eliminate the influence on the calibration result. Finally, the accuracy of grouped approach algorithm is analyzed. Experimental results show that principal point accuracy and the principal distance accuracy obtained by the proposed algorithm are reduced to 2.12 μm and 4.02 μm and improved by 2.43 times and 2.00 times respectively, comparing with the traditional exact measuring angle method in the same laboratory environment. The experimental results indicate that the calibration accuracy has been improved greatly..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 112005 (2012)
New High-Precision Transmission Method of Spatial Azimuth with Original Light Intensity Signal
Yang Zhiyong, Huang Xianxiang, Zhou Zhaofa, and Zhang Zhili
As the precision of existing method based on sine wave magneto-optically modulated polarized light is low, a new high precision method of passing azimuth with the extremum of original light intensity signal is presented. The model of calculating initial light intensity based on discretional light intensity signal is esAs the precision of existing method based on sine wave magneto-optically modulated polarized light is low, a new high precision method of passing azimuth with the extremum of original light intensity signal is presented. The model of calculating initial light intensity based on discretional light intensity signal is established. The formula of calculating glancing azimuth in wide-angle range and its implemental project are provided and a new high precision method of calculating azimuth in small-angle range is proposed. Simulation results and system error analysis show that, the system error of the new method in the paper is less than those of the existing methods, and it provides a reference to passing spatial azimuth with higher precision..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 112006 (2012)
Lasers and Laser Optics
Experimental Investigation on Multi-Wavelength Chaos of Erbium-Doped Fiber Ring Laser
Yang Rong, Zhang Li, and Yang Lingzhen
Based on the nonlinear Kerr effect, the multi-wavelength chaos is generated in erbium-doped fiber ring laser (EDFRL) experimentally. Period-doubling route to chaos is observed in time series. Numerical simulation is also carried out, and the numerical results agree with the experimental results well. The experimental rBased on the nonlinear Kerr effect, the multi-wavelength chaos is generated in erbium-doped fiber ring laser (EDFRL) experimentally. Period-doubling route to chaos is observed in time series. Numerical simulation is also carried out, and the numerical results agree with the experimental results well. The experimental results show that the optical spectra of multi-wavelength chaotic fiber laser can output five different wavelengths at most with the pump power increasing, and the output of each wavelength is chaotic after a tunable fiber Bragg grating filter..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 114001 (2012)
Machine Vision
Camera Calibration with Single Image Based on Two Orthogonal One-Dimensional Objects
Xue Junpeng, and Su Xianyu
A new method for camera calibration is proposed by utilizing a T-shaped target of two orthogonal one-dimensional (1D) objects. Through this method, only one projected image of 5 points with known coordinates on the T-shaped target is needed. Then according to the flexible target principle, 4 collinear points composed bA new method for camera calibration is proposed by utilizing a T-shaped target of two orthogonal one-dimensional (1D) objects. Through this method, only one projected image of 5 points with known coordinates on the T-shaped target is needed. Then according to the flexible target principle, 4 collinear points composed by the virtual and marked points can be determined, and finally the first-order radial distortion parameters of the lens are calibrated through the primality, associativity and cross-ratio invariability of the projective transformation. Using the calibrated distortion parameters to correct the image distortions, it is possible to calibrate the intrinsic and extrinsic parameters of the camera on the basis of coordinate transformation of the two orthogonal 1D objects. This method, using the linear solution to gain the distortion parameters of the lens, is able to prevent the parameters coupling in the nonlinear iterative optimization process in traditional methods. Experiments prove that if the distortion correction of the camera lens is not conducted, the camera calibration result will be unstable with the increase of image noises; while after conducting the distortion correction, a stable calibration result with high precision will be ensured when the initial values of a simple calibration are optimized. The calibration experiment is simple and easy to operate. Only one image is needed in realizing the calibration of the camera lens distortion and of the intrinsic and extrinsic parameters, thus the real-time operation can be realized..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 115001 (2012)
Nonlinear Distortion Correction of Camera Based on Coplanar Condition Equations
Zhang Zhengyu, Huang Shijie, Luo Chuan, and Sun Yan
According to the homologous points on different coplanar visual-angle images coplanar, the coplanar condition equations with nonlinear distortion coefficients are deduced, and the generalized inverse method of least square solution for nonlinear distortion parameters is put forward to ensure camera self-calibrating accAccording to the homologous points on different coplanar visual-angle images coplanar, the coplanar condition equations with nonlinear distortion coefficients are deduced, and the generalized inverse method of least square solution for nonlinear distortion parameters is put forward to ensure camera self-calibrating accuracy, because the fabricating and assembling errors of the camera optical system cannot be removed which results to nonlinear distortion between real image and ideal image to some extent. This calibrating method generates the nonlinear distortion coefficients from different visual-angle images with more than six code points, therefore it is simple and rapid because it doesn′t need high-precision calibration objects or camera moving platform, so the calibrating cost is low, compared with the traditional camera calibration. The examples have demonstrated this method is correct; therefore it is useful and effective..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 115002 (2012)
Fast and Close-Form Optimal Estimation of Absolute Orientation Problem
Li Long, Deng Zongquan, Li Bing, and Wu Xiang
A fast algorithm to solve the absolate orientation problem is proposed. The algorithm first formulates objective function by least square method. Then it decouples the rotation and translation. Finally it uses the Fobenius norm, determinant and adjoint matrix to formulate the close-form optimal estimation of the rotatiA fast algorithm to solve the absolate orientation problem is proposed. The algorithm first formulates objective function by least square method. Then it decouples the rotation and translation. Finally it uses the Fobenius norm, determinant and adjoint matrix to formulate the close-form optimal estimation of the rotation and translation. The proposed algorithm has high accuracy and noise-resistance, especially high computation speed because of the absence of singular value decomposition, which is commonly used in current employed algorithms. Results of numerical experiment show that, compared with Umeyama algorithm, one of the best absolute orientation algorithms, the proposed algorithm performs the same level of accuracy and noise-resistance and extremely faster speed, and it is suitable for the areas which require high real-time performance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 115003 (2012)
Research on Laser Threat Source Localization of Omni-Directional Laser Warning System Based on Scattering Laser Detection
Zhang Weian, Wang Long, and Ren Jianguo
In order to resolve the problem that scattering laser warning can only localize the scattering laser spot, but cannot trace back to the enemy laser source at the present time, A three-dimensional (3D) model in war field circumstances including the enemy laser source, the scattering laser spot on some flat and omni-direIn order to resolve the problem that scattering laser warning can only localize the scattering laser spot, but cannot trace back to the enemy laser source at the present time, A three-dimensional (3D) model in war field circumstances including the enemy laser source, the scattering laser spot on some flat and omni-directional laser warning systems is established. The analytic expressions of the scattering laser spot contour on flat and the object space half-field angle of any point on the contour relative to fish eye lens were obtained. Then the spot imaged on sensor was fish eye distortion corrected. And the points on spot edge were selected, accordingly the parameters of 3D model were acquired. Whereafter the parameters were combined with information of sensor array, thus azimuth and distance of the enemy laser source relative to the system could be attained finally. In the end the experimental results validated the method, the cause of errors was analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 115004 (2012)
Medical Optics and Biotechnology
High-Speed Line Scanning Confocal Laser Ophthalmoscope
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
High-speed line scanning confocal laser ophthalmoscope (LSO) uses a line beam to illuminate the retina, meanwhile a linear array CCD is used for imaging the retina. The magnification of the optical system is about 7 times, and the transverse resolution is less than 10 μm. For 1024 pixel×512 pixel imaging mode (theHigh-speed line scanning confocal laser ophthalmoscope (LSO) uses a line beam to illuminate the retina, meanwhile a linear array CCD is used for imaging the retina. The magnification of the optical system is about 7 times, and the transverse resolution is less than 10 μm. For 1024 pixel×512 pixel imaging mode (the sensor line frequency is 58 kHz), the frame frequency can achieve 110 frame/s. Therefore, images of an artificial human eye with high resolution and high frame frequency are achieved by the developed system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 117001 (2012)
Photodynamic Effect of Novel Photosensitizer Chlorophyllin f on Bladder Cancer T24 Cells
Li Bin, Chen Gang, Zhang Yuanfang, Fang Jie, Li Wenzhi, Wu Zhiming, Lu Jiancheng, and Chen Jiyao
T24 cells are incubated with a novel photosensitizer chlorophyllin f, and then irradiated by 650 nm laser light. MTT assay is used to detect the growth inhibition rate of T24 cells. The apoptosis of T24 cells is observed by flow cytometry. The Mito Tracker Green probe is used to label mitochondrion, and the confocal laT24 cells are incubated with a novel photosensitizer chlorophyllin f, and then irradiated by 650 nm laser light. MTT assay is used to detect the growth inhibition rate of T24 cells. The apoptosis of T24 cells is observed by flow cytometry. The Mito Tracker Green probe is used to label mitochondrion, and the confocal laser scanning microscopy excited by 488 nm and 405 nm dual channels is applied to reveal intracellular localization. With 4 J/cm2 of optical energy density, the growth inhibition rates of 2.5, 5 and 10 μg/mL chlorophyllin f are 17.68%, 49.35% and 84.42%, while with 1 J/cm2 optical energy density, the growth inhibition rates are 4.34%, 37.42% and 78.38% respectively. The apoptosis rate of treatment group is (45.23±1.2)%, significantly higher than control groups. The confocal laser scanning microscopy reveals that, the red fluorescence emitted by chlorophyllin f and green fluorescence emitted by Mito Tracker Green probe distributes almost the same. Therefore, the photodynamic effect of chlorophyllin f on T24 cells is significant. Chlorophyllin f mainly locates and functions at mitochondria, and induces apoptosis, which may be one of the mechanisms against T24 cells..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 117002 (2012)
Nonlinear Optics
Action of Indium Doping on Near Infrared Photorefractive Properties of Fe:LiNbO3 Crystal
Chen Baodong, and Wen Jing
In:Fe:LiNbO3 crystals have been grown by doping indium ions in Fe:LiNbO3 crystals. Experimental demonstrations are performed by recording in Fe:LiNbO3 and InFe:LiNbO3 crystals with a focused near infrared laser beam of 1064 nm wavelength. The near infrared photorefractive properties of Fe:LiNbO3 and InFe:LiNbO3 crystalIn:Fe:LiNbO3 crystals have been grown by doping indium ions in Fe:LiNbO3 crystals. Experimental demonstrations are performed by recording in Fe:LiNbO3 and InFe:LiNbO3 crystals with a focused near infrared laser beam of 1064 nm wavelength. The near infrared photorefractive properties of Fe:LiNbO3 and InFe:LiNbO3 crystals are comparatively studied by the digital observation device. The experimental research results show that the photorefractive response and the photorefractive resistance ability are improved highly, and the saturation refractive index change Δn decreases in the InFe:LiNbO3 crystal. The enhancement mechanism of photorefractive properties is preliminary discussed in InFe:LiNbO3 crystals. The modification of indium ions substitutes the sites of light sensitive centers in the InFe:LiNbO3 crystal, and the number of light sensitive centers is decreased rapidly. It also induces the improvement of photoconductive property and cut the response time..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 119001 (2012)
Dispersion Property Measurement of Photonic Crystal Fiber by Using Spontaneous Four Wave Mixing
Cui Liang, Li Xiaoying, and Zhao Ningbo
The dispersion property of a 0.6 m-long photonic crystal fiber (PCF) is deduced by characterizing its phase matching condition of spontaneous four wave mixing (SFWM) through pumping the PCF with a pulse train having a pulse duration of 1.6 ps. When the central wavelength of the pump is varied from 1037 to 1047 nm with The dispersion property of a 0.6 m-long photonic crystal fiber (PCF) is deduced by characterizing its phase matching condition of spontaneous four wave mixing (SFWM) through pumping the PCF with a pulse train having a pulse duration of 1.6 ps. When the central wavelength of the pump is varied from 1037 to 1047 nm with a step of 1 nm, the spectra of signal and idler photons via SFWM are measured by using tunable filters and single-photon detectors. Using the step effective index model, and fitting the 11 sets of experimentally obtained data of SFWM phase matching, the effective core radius and air fraction of the PCF are found to be 0.949 μm and 29.52%, respectively. Accordingly, the dispersion property and the SFWM phase matching curve of the PCF in the whole spectral range are then calculated. Experimental results show that the predicted wavelengths of phase matching agree with the measured values, and the differences are less than 0.1%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 119002 (2012)
Optical Design and Fabrication
Optics Design of Far Ultraviolet Imaging Spectrometer for Ionosphere Remote Sensing
Wu Yan, Tang Yi, Liu Jianpeng, Zhang Zhige, and Ni Guoqiang
Useing Czerny-Turner structure as the beam splitter a new optical design method of far ultraviolet imaging spectrometer used to get ionosphere data is presented. A source of aberration is analyzed. The method of aberration correction based on divergent illumination is proposed, which the imaging spectrometer is designeUseing Czerny-Turner structure as the beam splitter a new optical design method of far ultraviolet imaging spectrometer used to get ionosphere data is presented. A source of aberration is analyzed. The method of aberration correction based on divergent illumination is proposed, which the imaging spectrometer is designed by. The wavelength range, field of view, focal length and F number, respectively, are from 120 to 180 nm, 0.1°×6.0°, 121.8 mm and 6.2. The designed system is evaluated by modulation transfer function (MTF) and imaging simulation. Its spectral resolution is better than 1.0 nm and its spatial resolution is better than 0.1°, which can meet with the requirements of ionosphere observation. Without any aspherical mirror, the optics is easy to manufacture..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 122001 (2012)
Performance Analysis and Design of Paraboloidal Dish Solar Concentrators
Wang Yunfeng, Ji Jie, He Wei, and Chen Haifei
For paraboloidal dish solar concentrators, the concentrating characteristics of concentrators with different apertures but the same area are investigated respectively with the same focal length and the same rim angle through the ray tracing. Considering several geometric factors including the influence of the sun shapeFor paraboloidal dish solar concentrators, the concentrating characteristics of concentrators with different apertures but the same area are investigated respectively with the same focal length and the same rim angle through the ray tracing. Considering several geometric factors including the influence of the sun shape, the shape of apertures, focal length and rim angle of paraboloidal dish, the shadow of receivers and so on, with the optical properties of concentrators, the geometric models for simulation are established, and the average flux distribution on the receivers is simulated and drawn with the software of TracePro. In order to make a quantitative evaluation for the concentrating performance of concentrators, the concept of efficiency factor of area is applied. The results of simulation show that when the area of apertures is same, the average flux distributions for the four concentrators with different shapes and identical focal length are similar. However, for those with different shapes but same rim angle, the average flux distributions have large attenuation except the concentrator with circular aperture. The solar concentrator of multiple panels with the same focal point is designed, and its concentrating performance is analyzed. The simulation results could present a useful reference for design and optimization of the solar paraboloidal dish concentrator..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 122002 (2012)
Nonlinear Optimization of Light Intensity Spatial Distribution for LED Road Luminaires
Lai Wei, Chen Weimin, Liu Xianming, Lei Xiaohua, and Hu Shunren
The primary purpose of road lighting is to satisfy the visual requirements of road users, and then to reduce the energy consumption as possible. Moreover, these two factors are closely related to the light intensity spatial distribution of road luminaires. Only one type of light distribution is not applicable to differThe primary purpose of road lighting is to satisfy the visual requirements of road users, and then to reduce the energy consumption as possible. Moreover, these two factors are closely related to the light intensity spatial distribution of road luminaires. Only one type of light distribution is not applicable to different roads and installation conditions of road luminaires. In view of three typical roads as major road, collector road and local road, a reverse method is proposed to design the most energy-saving light distribution of LED road luminaires based on the specific road conditions, installation parameters of road luminaires and practical visual requirements for drivers. A nonlinear optimization model is established, which takes the visual requirements of drivers as the constraint conditions and the minimum total luminous flux of LED luminaires as the goal. Then a polynomial of cosine function for the illumination distribution on road is used, and a two-level optimization strategy is proposed for the nonlinear optimization. Finally, the most energy-saving light distributions are obtained at three different road conditions. Compared with the light distribution of LED road luminaires designed by equal illuminance distribution method, the LED road luminaires with the proposed nonlinear method can significantly improve the quality of visual lighting environment on the road and save energy by about 30%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 122003 (2012)
Optical Devices
Tunable Optical Power Splitter Based on the Point Defects of Two-Dimensional Photonic Crystal
Wang Rong, Liang Binming, Zhang Lichao, and Zhuang Songlin
In two-dimensional rectangular array photonic crystal, one parallel line waveguides are formed by removing the middle line silicon pillars. On the right of the line waveguide, a point waveguide has been introduced. It′s coupling properties are investigated by use of finite-difference time-domain (FDTD) method and the sIn two-dimensional rectangular array photonic crystal, one parallel line waveguides are formed by removing the middle line silicon pillars. On the right of the line waveguide, a point waveguide has been introduced. It′s coupling properties are investigated by use of finite-difference time-domain (FDTD) method and the splitting ratio of two channels has been counted. The results show that the splitting ratio changes obviously is found when the temperature of the photonic crystal is rising. A new optical power splitter is brought forward based on this research and a wide range of light power ratios, from 11 to 901 can be obtained. This function can be realized by regulating the temperature from 0 ℃ to 200 ℃. Finally a three channels and tunable optical power splitter is designed, which can distribute the power of the light by adjusting the two point defects′ temperature..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 123001 (2012)
Linear Electrooptic and Electrogyration Intensity Modulation Using Crystalline Quartz
Li Changsheng
A linear electrooptic modulator using crystalline quartz is proposed and experimentally investigated, and its optical bias is produced in the crystal itself. Required optical bias can be produced from the natural birefringence and optical activity of a crystal if the dimensions of the crystal and its dielectric axis azA linear electrooptic modulator using crystalline quartz is proposed and experimentally investigated, and its optical bias is produced in the crystal itself. Required optical bias can be produced from the natural birefringence and optical activity of a crystal if the dimensions of the crystal and its dielectric axis azimuth to light propagating direction are properly designed. For crystals exhibiting both electrooptic Pockels effect and electrogyration effect, such as crystalline quartz, it is better to simultaneously make use of the two effects to increase its modulating sensitivity. The experiment on electrooptic intensity modulation using crystalline quartz is performed for the modulating voltage from 27 V to 4.5 kV, and the linear correlation coefficient between output signal and modulating voltage is no less than 0.9999..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 123002 (2012)
Application of PbS Quantum Dots in Luminescent Solar Concentrator
Zhang Jun, Zhang Jun, Geng Junjie, Zhang Yi, Ding Jianjun, Sun Song, Luo Zhenlin, Bao Jun, and Gao Chen
Luminescent solar concentrator (LSC) collects sunlight equivalently through the effect of planar optical waveguide, and cuts the cost of photovoltaic electricity generation by reducing the consumption of solar cells. Quantum dot (QD) LSC is fabricated by sandwiching colloidal PbS QDs hexane solution in two glasses to fLuminescent solar concentrator (LSC) collects sunlight equivalently through the effect of planar optical waveguide, and cuts the cost of photovoltaic electricity generation by reducing the consumption of solar cells. Quantum dot (QD) LSC is fabricated by sandwiching colloidal PbS QDs hexane solution in two glasses to form solution sandwiching planar waveguide and coupling commercial monocrystalline Si solar cells whose efficiency is 17%. The QD-LSC absorbs the 700~1100 nm near infrared solar radiation and its standard efficiency is about 1.31%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 123003 (2012)
Two-Stage Photonic Crystal Beam Compressor Based on Silicon Nanowire Waveguide
Cui Naidi, Liang Jingqiu, Liang Zhongzhu, and Wang Weibiao
Considering the significant value of the compression of the light beam for all optic networks and future integrated photonic/optical circuit, a beam compressor with two-stage compressions based on the efficient coupling between photonic crystal waveguides and nanowire waveguide is proposed. The first stage compression Considering the significant value of the compression of the light beam for all optic networks and future integrated photonic/optical circuit, a beam compressor with two-stage compressions based on the efficient coupling between photonic crystal waveguides and nanowire waveguide is proposed. The first stage compression relies on the coupling between W1 and W5 photonic crystal waveguides. A nanowire waveguide with a width of 0.1 μm and a length of 3.06 μm is introduced to realize the second stage compression. The parameter of the rod located between the W1 photonic crystal waveguide and nanowire waveguide is optimized. When the radius of the rodis 0.04 μm, transmission efficiency and full-width at half-maximum (FWHM) of the output beam of the beam compressor are 93.4% and 0.148 μm, respectively. The compression ratio reaches to 16.08..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 123004 (2012)
Preparation and Temperature-Variation Properties of High Color Rendering Index LED
Cui Desheng, Guo Weiling, Cui Bifeng, Yan Weiwei, and Liu Ying
Two kinds of high color rendering index light emitting diode (LED) are made by yellow, red phosphor and yellow, red, green phosphor respectively. The light output of the sample with green phosphor is bigger due to more green light in spectrum after the addition of green phosphor and the larger vision function of green Two kinds of high color rendering index light emitting diode (LED) are made by yellow, red phosphor and yellow, red, green phosphor respectively. The light output of the sample with green phosphor is bigger due to more green light in spectrum after the addition of green phosphor and the larger vision function of green light than that of red light. The luminous efficiency decreases and color rendering index increases when the testing temperature varies from 10 ℃ to 90 ℃. This suggests that, besides the degradation of internal quantum efficiency, the mismatch of red shift of wavelength of the chip and the excitation wavelength of phosphor and the degradation of excitation efficiency of phosphor at high temperature are all the reasons of degradation of luminous efficiency. The color rendering index increases due to wider spectrum of blue light emitted by the chip at high temperature which makes the spectrum smoother and closer to the spectrum of the sun..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 123005 (2012)
Optics at Surfaces
Using Surface Plasmon Resonance to Control the Reflection Index of Mirror
Peng Yang, Hou Jing, Huang Zhihe, and Lu Qisheng
The calculation of the temperature-dependent dielectric function of metal is modified. A method to control the reflection index of mirror by using the surface plasmon resonance (SPR) is proposed. A polymer film with high thermooptic coefficient is coated on the metal film in the Kretschmann configuration. The variationThe calculation of the temperature-dependent dielectric function of metal is modified. A method to control the reflection index of mirror by using the surface plasmon resonance (SPR) is proposed. A polymer film with high thermooptic coefficient is coated on the metal film in the Kretschmann configuration. The variations of metal film thickness and dielectric constants for all layers with temperature are calculated, and the proposed device is numerically simulated by using the characteristic matrix method. The results show that when the incident wavelength is 532 nm, the temperature is controlled between 10 ℃ and 90 ℃, the reflection index can be controlled from 52.8% to 41.5% for 70° incident angle and 31.1% to 18.8% for 75° incident angle, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 124001 (2012)
Propagation Properties of Y-Splitters Based on MIM Surface Plasmonic Waveguides
Li Juan, Wang Bingyan, and Xue Wenrui
Using the two-dimesional finite-difference time-domain (FDTD) method, the dependence of the reflectivity, the transmission rate and the energy splitting ratio, on the geometrical parameters of two kinds of Y-splitter with sine shaped arc and circular shaped arc, based on mental-insulator-mental (MIM) surface plasmonic Using the two-dimesional finite-difference time-domain (FDTD) method, the dependence of the reflectivity, the transmission rate and the energy splitting ratio, on the geometrical parameters of two kinds of Y-splitter with sine shaped arc and circular shaped arc, based on mental-insulator-mental (MIM) surface plasmonic waveguides, are analysed. Results show that the transmission characteristics of the two Y-splitters depend obviously on the parameter of the width of the waveguides and weakly on the two parameters of the offsets of the two output branches and the lengths of the curves. The transmission characteristics of the Y-splitter whose curves are circular arc-shaped are better than the Y-splitter whose curves are sine arc-shaped within 600~1500 nm. For asymmetrical Y-splitter, the reflectivity, the transmission rate and the power splitting ratio are affected obviously by the parameter of offset when the curves are sine arc-shaped and the energy splitting ratio can be up to 2∶1. The reflectivity, the transmission rate and the power splitting ratio are affected faintly by the parameter of offset when the curves are circular arc-shaped..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 124002 (2012)
OPTOELECTRONICS
Photoluminescence Study of Two Layer Stacked InAs/GaAs Quantum Dots
Wei Quanxiang, Wu Bingpeng, Ren Zhengwei, He Zhenhong, and Niu Zhichuan
The molecular beam epitaxy growth and physical property of photoluminescence (PL) of two layer stacked InAs/GaAs quantum dots have been investigated. The emission wavelengths of the InAs quantum dots (QD) are extended to 1391~1438 nm through optimizations of growth conditions including InAs deposition amounts, thicknesThe molecular beam epitaxy growth and physical property of photoluminescence (PL) of two layer stacked InAs/GaAs quantum dots have been investigated. The emission wavelengths of the InAs quantum dots (QD) are extended to 1391~1438 nm through optimizations of growth conditions including InAs deposition amounts, thicknesses of GaAs space layers and growth temperatures. It is found that the PL intensities, wavelengths, line widths and uniformities of the high density (2×1010 cm-2) InAs QD are improved by using in-situ annealing of GaAs interval layers and Sb assisted growth of InGaAs cover layers..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 125001 (2012)
Physical Optics
Magneto-Otical Conductivity Induced by Electron-Impurity and Electron-Phonon Interaction in Graphene
Yang Cuihong, Xu Wen, and Li Qingfang
A theoretical study on the optical conductivity in the presence of perpendicular magnetic fields and scattering centers such as charged impurities and optical phonons in graphene is presented. The standard Kubo formula is employed to evaluate the magneto-optical conductivity. The screaning effect of the dielectric enviA theoretical study on the optical conductivity in the presence of perpendicular magnetic fields and scattering centers such as charged impurities and optical phonons in graphene is presented. The standard Kubo formula is employed to evaluate the magneto-optical conductivity. The screaning effect of the dielectric environment is included in the calculation of the electron-impurity interation and the self-energy induced by impurity and optic-phonon scattering and the Green′s function for a carrier are calculated self-consistently. In a strong magnetic field, the single impurity scattering is a good approximation. It is found that the charged impurity scattering results in a symmetric Landau level broadening while the combined charged impurity and optical phonon scattering can lead to an asymmetric broadening of density of states (DOS). The peak position and intensity of the magneto-optical conductivity depend strongly on the filling factor and the broadened DOS..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 126001 (2012)
Quantum Optics
Improvement of Balanced Homodyne Detector
Wang Jinjing, Jia Xiaojun, and Peng Kunchi
Balanced homodyne detection technology is one of the best methods for detecting the quantum noise of a quantum state in continuous variable quantum information. In the balanced homodyne detection system, a pair of detectors with the same performance are needed to effectively detect the noise limit and the quantum fluctBalanced homodyne detection technology is one of the best methods for detecting the quantum noise of a quantum state in continuous variable quantum information. In the balanced homodyne detection system, a pair of detectors with the same performance are needed to effectively detect the noise limit and the quantum fluctuations of quantum states for totally eliminating classical noises. Based on the Kirchhoff current law and the scheme of photodiodes in series, a type of balanced homodyne detector with excellent capability is designed and set up. The photo-current signal is obtained from the series connection nodes of photodiodes and then amplified, thus the requirement of identity for the two detectors is degraded and the quality of the balanced homodyne detection system is improved at the same time. The experimentally measured common-mode rejection ratio (CMRR) of the detector is 39 dB at 2 MHz. The improved detector with low noise, good linear gain and high CMRR can satisfy the requirements of quantum information experiments..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 127001 (2012)
Remote Sensing and Sensors
Study on Airborne Multi-Pulse Ladar Target Signal Simulator
Ma Pengge, Qi Lin, Yang Yi, and Jin Qiuchun
Airborne multi-pulse ladar target signal simulator is studied to evaluate the performance of echo signal digital processing algorithms and hardware platform. It is pointed out that only using radar equation to establish the echo waveform model is inadequate for the relationship between waveform and energy. Air target eAirborne multi-pulse ladar target signal simulator is studied to evaluate the performance of echo signal digital processing algorithms and hardware platform. It is pointed out that only using radar equation to establish the echo waveform model is inadequate for the relationship between waveform and energy. Air target echo pulse broadening is analyzed, and the waveform time broadening data are acquired under different angles, target distances and target sizes. Because the energy remains same before and after broadening, the echo waveform mathematic model is established through solving the characteristic parameters of Gaussian pulse function. Then the simulation model based on target distance error and echo pulse waveform error statistic characteristics is given, and the method to generate echo signal according to the signal-to-noise ratio (SNR) is proposed based on the standardization of echo noise root mean square (RMS) value. The performances about echo SNR error, minimum output SNR, and continuous working time of two laser simulators are compared..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 128001 (2012)
Spectroscopy
Modification of Light Emitting Diode′s Normalized Spectrum Model
Wen Yumei, Zhao Xuemei, Li Ping, Wen Jing, and Zhang Min
Primarily due to self-absorption, there is obvious discrepancy between the spectra from the light emitting diode′s (LED) normalized model and the actually measured spectra. In order to make the model fit the actual spectrum, the modification of LED′s normalized spectrum model is investigated. The self-absorption spectrPrimarily due to self-absorption, there is obvious discrepancy between the spectra from the light emitting diode′s (LED) normalized model and the actually measured spectra. In order to make the model fit the actual spectrum, the modification of LED′s normalized spectrum model is investigated. The self-absorption spectrum is gotten from the subtraction of the spectrum from the normalized spectrum model and the actual spectrum. Through the analysis of the dependence of the peak light intensity and the full width at half maximum in self-absorption spectrum on temperature and the relation between its peak energy and the actual spectrum′s, the self-absorption spectrum′s expression is provided. The fitting expression is obtained by combining Gaussian spectrum model and the normalized spectrum model. The expression is used to modify the normalized spectrum model. Experimental results show that errors by the modified model are less than 4% at various temperatures, thus the spectra from the modified normalized model agree with the actual ones..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 130001 (2012)
Research on Measurement Method for Sulfur Content in Coal Based on Ultraviolet Differential Optical Absorption
Song Feihu, Xu Chuanlong, and Wang Shimin
Determining sulfur content in coal rapidly and accurately can provide technical basis for the enterprises and environmental monitoring departments. A novel method for measuring sulfur content in coal based on ultraviolet (UV) differential optical absorption spectroscopy (DOAS) is put forward. Compared with atmosphere mDetermining sulfur content in coal rapidly and accurately can provide technical basis for the enterprises and environmental monitoring departments. A novel method for measuring sulfur content in coal based on ultraviolet (UV) differential optical absorption spectroscopy (DOAS) is put forward. Compared with atmosphere monitoring, the UV DOAS used in the sulfur content measurement in coal encounters with the problems that the concentration range of SO2 is wider and the optical path length of the gas cell is shorter. In order to solve the problems, an improved DOAS algorithm based on finite impulse response (FIR) filter and nonlinear compensation is proposed on the basis of the traditional algorithm. An experimental system is designed and built, on which five kinds of standard coals are experimentally tested. Results show that the lower detection limit of the system is 0.014% and the influence of the dust and background gas on SO2 concentration measurement can be reduced. The repeatability of the measurement system meets the national standards of China. The system has the advantages of low maintenance and short measurement duration (4 min)..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 130002 (2012)
Two-Photon Excitation for H2O and HLi
Zhu Zhenghe, Wan Mingjie, Tang Yongjian, and Meng Daqiao
The two-photon excitation is studied by the full relativistic theory of H2O and HLi. The single-photon excitation of H2O and HLi molecules is also studied using symmetry adapted cluster/configuration interaction (SAC-CI) method for comparison. The excitation probability of two-photon excitation is 3~5 orders of magnituThe two-photon excitation is studied by the full relativistic theory of H2O and HLi. The single-photon excitation of H2O and HLi molecules is also studied using symmetry adapted cluster/configuration interaction (SAC-CI) method for comparison. The excitation probability of two-photon excitation is 3~5 orders of magnitude less than that of single-photon excitation. It is better to use the full relativistic theory, which involves both space and time symmetry, for the calculation of two-photon excitation..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 130003 (2012)
Measurement of Absorption Spectra of CO2 at 6320~6336 cm-1 Using Temperature Tuning Technique
Li Jinyi, Du Zhenhui, Qi Rubin, and Xu Kexin
There are some disadvantages in the current tunable diode laser absorption spectroscopy (TDLAS), such as tuning range, tuning time and system complexity. A fast temperature tuning method of broad spectrum is developed and the dynamic wavelength of the laser is calculated precisely during the temperature tuning by meansThere are some disadvantages in the current tunable diode laser absorption spectroscopy (TDLAS), such as tuning range, tuning time and system complexity. A fast temperature tuning method of broad spectrum is developed and the dynamic wavelength of the laser is calculated precisely during the temperature tuning by means of thermo-electric cooler (TEC) and negative temperature coefficient (NTC) thermistor integrated in laser diode module. The spectral measurements of CO2 absorption lines from 6320 to 6336 cm-1 are performed at room temperature by using fiber-coupled distributed feedback (DFB) diode laser operating at 1.58 μm with measurement time less than 3 s. Eight strong absorption lines are obtained and are compared with HITRAN 2008 database, which shows that the deviations of absorption line positions, line strength and full-width at half-maximum (FWHM) are less than 1%, 3% and 6%, respectively. Additionally, the corresponding spectral parameters of 14 weak absorption lines are very consistent with those in HITRAN 2008 database..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 130004 (2012)
Thin Films
Analysis of the Half-Wave Hole for Symmetrical Harmonic Beam Splitter Based on Equivalent Layer Theoretics
Han Jin, Zhang Jinlong, Cheng Xinbin, and Wang Zhanshan
Half-wave hole has seriously influenced the application of harmonic beam splitters in high-power laser systems. Half-wave holes of the quarter wavelength symmetrical coatings usually caused by overall thickness mismatch and materials dispersion mismatch of the high and low refractive index films are simulated in order Half-wave hole has seriously influenced the application of harmonic beam splitters in high-power laser systems. Half-wave holes of the quarter wavelength symmetrical coatings usually caused by overall thickness mismatch and materials dispersion mismatch of the high and low refractive index films are simulated in order to conduct further research on their formation mechanism. Based on the theory of equivalent layers, the equivalent refractive index of a symmetrical design is calculated on Matlab platform. Consequently, the corresponding reflectance envelope is depicted. Through the study on the relation among the equivalent refractive index, reflectance spectrum and reflectance envelope of different designs, the characteristics of half-wave holes such as location, size and change tendency are analyzed in principle. Computational results indicate that thickness mismatch gives rise to equivalent refractive stop-band in the half wave of spectrum. The more the number of layers is, the more serious the thickness mismatch and dispersion mismatch are, the deeper the half-wave hole will be for a harmonic beam splitter..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 131001 (2012)
Study and Fabrication of Filter Film in Laser Identification Between Friend or Foe System
Yang Yongliang, Liu Guojun, Fu Xiuhua, and Li Meixuan
According to the requirement of laser identification between friend or foe system, chosing H4 as the material of high refractive index and SiO2 as the material of low refractive index, the film system is designed and optimized with the help of Macleod and TFCalc software. Adopting electron beam vaccum deposition methodAccording to the requirement of laser identification between friend or foe system, chosing H4 as the material of high refractive index and SiO2 as the material of low refractive index, the film system is designed and optimized with the help of Macleod and TFCalc software. Adopting electron beam vaccum deposition method with the aid of ion assistant deposition technology as well as using orthogonal matrix tests to adjust and optimize technological parameters of the materials, using two sides of the substrate to broaden the long and short wavelenth reflection bands respectively, the monitoring problem of thicker stack on one side has been solved and filter film to meet the demand has been deposited. The reflectances at 532, 632, 905, 1064 and 1550 nm wavelengths are less than 0.2%, and it makes the transmittance over 95% at 808 nm wavelength. The laser induced damage thresholds (LIDTs) of the filter at 532 nm and 1064 nm are higher. Moreover, the filter can endure the test of bad environment, meeting the using requrement of the identification between friend or foe system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 131002 (2012)
Nanoporous Antireflective Coating Fabricated by Organic-Inorganic Hybrid Nanoparticles
Xu Yunli, Li Chaolong, Jiang Hao, and Wang Yuechuan
A facile route to prepare nanoporous antireflective coating (ARC) composed of organic/inorganic latex particles of poly(2,2,3,3-terafluoropropyl methacrylate -co-γ-methacryloxypropyltrimethoxysilane [P(TFPMA-co-TMSPMA)] on glass substrates by spin-casting binary latexes of P(TFPMA-co-TMSPMA)/polystyrene (PS), and then A facile route to prepare nanoporous antireflective coating (ARC) composed of organic/inorganic latex particles of poly(2,2,3,3-terafluoropropyl methacrylate -co-γ-methacryloxypropyltrimethoxysilane [P(TFPMA-co-TMSPMA)] on glass substrates by spin-casting binary latexes of P(TFPMA-co-TMSPMA)/polystyrene (PS), and then selectively removing the PS particles with cyclohexane is reported. The effects of concentration of binary latexes, rotation speed, as well as the size of the latex particles on the antireflective performance are studied. Nanoparticle coatings which exhibited satisfying antireflective performance in the wavelength range of 400~1100 nm and with the highest transmittance above 99.1% are prepared with thickness in 109~208 nm and refractive indices about 1.22~1.25. It is also found that the surface roughness and the optical transmittance of the nanoporous coatings are related with the size of the latex particles used for the ARC. Nanoparticle coatings with reduced surface roughness can be prepared with latexes of smaller particle size..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 32, Issue 1, 131003 (2011)
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