Contents
2009
Volume: 29 Issue 2
56 Article(s)
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Atmospheric Optics and Oceanic Optics
Performance of Liquid-Crystal Spatial Light Modulator Using for Wave-Front Correction
Cai Dongmei, Yao Jun, and Jiang Wenhan
Liquid-crystal spatial light modulator (LC-SLM) has the attractive advantages of large number of correcting elements, low applied voltage, easy control and low cost etc. as an emerging wave-front corrector. Based on the investigation of its time-space characteristics, the capability and limitations of LC-SLM in adaptivLiquid-crystal spatial light modulator (LC-SLM) has the attractive advantages of large number of correcting elements, low applied voltage, easy control and low cost etc. as an emerging wave-front corrector. Based on the investigation of its time-space characteristics, the capability and limitations of LC-SLM in adaptive astronomical imaging application systems were discussed. An adaptive optical system with a LC-SLM and a Shack-Hartmann sensor was close-looped. As a result, a static aberration, which is mainly composed of low order aberrations, was corrected. RMS value and PV value after closed-loop correction are reduced from 0.628λ, 2.872λ to 0.031λ and 0.337λ, with a Strehl ratio improvement from 0.04 to near diffraction-limited of 0.81. Apart from that, the diffraction efficiency of LC-SLM was calculated and measured. From the result, LC-SLM is capable of correcting atmosphere turbulence nicely. However, Low optical efficiency and response speed are huge drawbacks to limit LC-SLM in a practical adaptive optical system to correct atmospheric aberration in real time and using for faint object..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 285 (2009)
Lidar Study of the Aerosol Characteristic in Beijing During Traffic Controlled
Dong Yunsheng, Liu Wenqing, Liu Jianguo, Xie Pinhua, Lu Yihuai, Zhao Xuesong, Han Daowen, Zhang Tianshu, Liu Zengdong, and Huang Shuhua
The effect of traffic controlled on the air pollution in city was studied by micro pulse lidar (MPL). The optical characteristic of subaerial aerosol over Beijing was monitored continually with MPL in August of 2007. The system structure and technical parameters of MPL were presented and the data-processing method was The effect of traffic controlled on the air pollution in city was studied by micro pulse lidar (MPL). The optical characteristic of subaerial aerosol over Beijing was monitored continually with MPL in August of 2007. The system structure and technical parameters of MPL were presented and the data-processing method was discussed, the time-space distribution of aerosol extinction coefficients, heights of planetary boundary layer (PBL) and aerosol mass concentration were showed and compared with the results which were measured in the similar meteorologic condition during traffic uncontrolled. The results indicate that the aerosol mass concentration was falling, and the height of air pollution mass changed thin. All these proved that the program of traffic controlled improved the quality of city air. The experiment provide scientific groundwork and reference to the study of the air pollution..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 292 (2009)
Study on Scanning Differential Optical Absorption Spectroscopy for Monitoring Vertical Profiles of Atmospheric Pollutant
Zhu Yanwu, Xie Pinhua, Dou Ke, Liu Shisheng, Qin Min, Li Suwen, Si Fuqi, and Liu Wenqing
Differential optical absorption spectroscopy （DOAS） has become a widely used method for the simulataneous detection of atmospheric trace gases with low detection limits. DOAS method is proposed for monitoring the vertical distribution of atmospheric trace gases . Based on DOAS technique and a high tower with angle-reflDifferential optical absorption spectroscopy （DOAS） has become a widely used method for the simulataneous detection of atmospheric trace gases with low detection limits. DOAS method is proposed for monitoring the vertical distribution of atmospheric trace gases . Based on DOAS technique and a high tower with angle-reflectors, the scanning long-path(LP)-DOAS system is developed . Field observations of vertical distribution of NO2 was performed by using the scanning LP-DOAS system in the summer of 2007. The NO2 concentrations along three light paths were accurately measured, and the detection limits along three light paths and the total systematic error were obtained. The vertical profiles and vertical gradient of NO2 were successfully retrieved by using the vertical profiles model. The results indicate that the scanning LP-DOAS system can perform vertical observations of trace gases in the urban boundary layer..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 297 (2009)
Measurement of Path-Averaged Transverse Wind Speed with a Shack-Hartmann Wave-Front Sensor
Yuan Ke′e, Zhu Wenyue, Huang Yinbo, and Rao Ruizhong
By measuring time lagged cross correlation function with a pair of sub-apertures of Shack-Hartmann wave-front sensor, the path-averaged transverse wind speed and wind direction can be found directly from the slope of this function with no time delay. Experiential formula to calculate the path-averaged wind speed is dedBy measuring time lagged cross correlation function with a pair of sub-apertures of Shack-Hartmann wave-front sensor, the path-averaged transverse wind speed and wind direction can be found directly from the slope of this function with no time delay. Experiential formula to calculate the path-averaged wind speed is deduced. And the experiment on it in 1000 m horizontal propagating path was carried out for the first time by use of a Shack–Hartmann wave-front sensor. Some results were found. Firstly, the correlation coefficients of wind speed reach 0.988 from different pairs of sub-apertures; secondly, the results from different pairs of sub-apertures were averaged, and the variation trend was in accord with gained from an anemometer placed in the 15-m tower. The correlation coefficients of two typical experiments are 0.848 and 0.820 respectively. All the experimental results indicate that measuring path-averaged transverse wind speed by Shack-Hartmann wave-front sensor is feasible, which extends the function of this sensor..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 303 (2009)
Fiber Optics and Optical Communications
Wavelength-Division Demultiplexer Based on FBG Coupler
Pei Li, Zhao Ruifeng, Ning Tigang, Dong Xiaowei, Wei Yan, Qi Chunhui, and Ruan Yi
By using the reflectivity property of fiber Bragg grating (FBG) and the coupling property of coupler, a wavelength-division demultiplexer based on FBG coupler is designed. The WDM signals are injected from the input port of the coupler, and the signal which has the same wavelength as that of FBG will be output from theBy using the reflectivity property of fiber Bragg grating (FBG) and the coupling property of coupler, a wavelength-division demultiplexer based on FBG coupler is designed. The WDM signals are injected from the input port of the coupler, and the signal which has the same wavelength as that of FBG will be output from the demultiplex port of the coupler, and the other signals will be output from the output port of the coupler, thus the demultiplex is implemented. The experiment of two signals with different wavelengths of 1554.248 nm and 1555.859 nm are implemented, and the extinction ration of each is 57 dB, and the center wavelength of FBG is 1555.86 nm. The results show that the signal output from the demultiplex port with extinction ration of 48 dB..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 308 (2009)
Spectrum-Sliced Wavelength Division Multiplexed Passive Optical Networks and Effects of Chromatic Dispersion
Shou Guochu, Hu Yihong, Guo Zhigang, and Qian Zongjue
Spectrum-slicing is an attractive WDM technique for realizing colorless ONUs in wavelength division multiplexed passive optical network (WDM-PON). It uses wavelength multiplexer (λmUX) as optical filters to obtain a spectral slice of light from a broadband light source (BLS) and modulates encode data onto the slice. A Spectrum-slicing is an attractive WDM technique for realizing colorless ONUs in wavelength division multiplexed passive optical network (WDM-PON). It uses wavelength multiplexer (λmUX) as optical filters to obtain a spectral slice of light from a broadband light source (BLS) and modulates encode data onto the slice. A theoretical analysis elucidates that the effects of chromatic dispersion will reduce because the spectrum outside the bandwidth of λMUX will be filtered out after spectrum slicing. At the 20 nm CWDM channel spacing, 155 Mb/s per channel at distance of 20 km on a G.625 fiber is supported with optical power penalty less than 1 dB; while at 0.8 nm DWDM channel spacing, 2.5 Gb/s per channel is supported with optical power penalty less than 0.5 dB. Direct modulation colorless ONU at 125 Mb/s is proposed and demonstrated by using LED with centre wavelength at 1550 nm, output power of -10 dB and a bandwidth of 70 nm. A four-channel WDM-PON over 20 km fiber with channel spacing of 20 nm is tested. The result shows optical power penalty caused by chromatic dispersion is less than 1 dB and optical power margin is more than 5.6 dB..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 312 (2009)
Simulation on Covert Communication System Based on Coherent OCDMA Technology
Yu Luochen, Lu Lin, Zhu Yong, and Zhang Qiufang
The concept of covert communication in optical domain and its performance estimation indexes of imperceptibility, usability, and robustness were illuminated. The method of optical domain covert communication based on coherent optical code division multiple access (OCDMA) technology was analyzed. Three covert schemes anThe concept of covert communication in optical domain and its performance estimation indexes of imperceptibility, usability, and robustness were illuminated. The method of optical domain covert communication based on coherent optical code division multiple access (OCDMA) technology was analyzed. Three covert schemes and their system configuration parameters were offered. Aiming at the properties of existing optical communication host channel, code-shift-keying (CSK) balance modulation and double side band en/decoder based on equivalent phase shift-superstructure fiber Bragg grating (EPS-SSFBG) were proposed to improve the performance of the system. The simulation results show that the proposed schemes can obtain a good performance. With signal-to-noise rate (SNR) of -13 dB, under the condition that the signal was completely covered by channel noise, and in this situation, the system still kept communication with a bit rate of 1.25 Gb/s, the inter-influence between covert signal and host signal was suppressed..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 316 (2009)
Adaptively Modulated Optical Orthogonal Frequency Division Multiplexing System with Variable Guard Interval
Zhang Jing, Qiu Kun, Li Yonggang, Zhou Yu, and Zhang Hongbo
It is indispensable to make use of guard interval to overcome intersymbol interference (ISI) caused by chromatic dispersion for optical orthogonal frequency division multiplexing (OOFMD) . However, the channel delay is not constant in different transmission distances and conditions, fixed guard interval decreases the pIt is indispensable to make use of guard interval to overcome intersymbol interference (ISI) caused by chromatic dispersion for optical orthogonal frequency division multiplexing (OOFMD) . However, the channel delay is not constant in different transmission distances and conditions, fixed guard interval decreases the power and spectrum availabity considerably. A novel adaptive cyclic prefix (ACP) OFDM concept is proposed. The lower limit value of CP, which can be determined by differential mode delay （DMD） and transmission distance, can eliminate influence of ISI. Simulation results demonstrate that the system can transmit a data rate 10 Gb/s about 1 km with reasonable CP without sacrificing the BER performance compared with the conventional non-adaptive CP..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 323 (2009)
Multimode Fiber Based Temperature Sensor with the Capability of Wavelength Encoding
Zhang Yan, Zhang Jianzhong, Liu Zhihai, Sun Weimin, Yuan Libo, and Peng Gangding
The theory analysis and experiments of multimode fiber (MMF) temperature sensors with the capability of wavelength encoding are presented. The analysis based on multimode-interference predicts the characteristic dip-wavelength positions of the MMF sensor according to the radius, the length and the refraction index of tThe theory analysis and experiments of multimode fiber (MMF) temperature sensors with the capability of wavelength encoding are presented. The analysis based on multimode-interference predicts the characteristic dip-wavelength positions of the MMF sensor according to the radius, the length and the refraction index of the MMF. It is used to optimize the sensor to produce only one characteristic dip-wavelength for a MMF temperature sensor in the wavelength range of a broadband source ASE. Three MMF temperature sensor heads with the length of 4 cm, 5.5 cm and 10 cm, packaged by a micro-silicon-tube, are fabricated and tested based on the ASE source with the wavelength range from 1525 nm to 1565 nm and optical spectral analyzer with the resolution of 0.01 nm separately. MMF temperature sensors with only one dip-wavelength and the temperature sensitivities ～13 pm/℃ are gained, which agrees with the theoretical analysis well..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 327 (2009)
Research on the Beam with Orbital Angular Momentum Used in Encoding and Decoding of Optical Communication
Lü Hong, and Ke Xizheng
Non-diffracting beams possess advantages of better direction and far distance for applications to free-space communications. During free propagation, their profiles of transverse intensity remain nearly invariant in a range. Some non-diffracting beams have orbital angular momentum. By analyzing the characteristic of thNon-diffracting beams possess advantages of better direction and far distance for applications to free-space communications. During free propagation, their profiles of transverse intensity remain nearly invariant in a range. Some non-diffracting beams have orbital angular momentum. By analyzing the characteristic of the beam with orbital angular momentum and non-diffracting beams transmission, the computer-generated hologram was used as spatial light modulator with reflective phase modulation to implement optical transformation. Laguerre-Gaussian beam carrying the information is transformed to a higher-order Bessel non-diffractive beam with the same topological charge by a mode converter consistina of axicon. A method of encoding and decoding of optical communication was proposed based on the non-diffracting high-order Bessel beams with orbital angular momentum. The proposed approach not only ensures the security of atmospheric laser communication, but also improves the density and precision of information transmission greatly..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 331 (2009)
Temperature Sensitization Model of Fiber Bragg Grating with Metal Coating
Feng Yan, Zhang Hua, Li Yulong, and Peng Gang
The optical fiber Bragg grating (FBG) sensor has great potential to be used for measuring temperature, strain, or even detecting fracture in metal materials. Embedding FBG sensor into metal materials is difficult and changing. Metal coating is one of the most efficient methods to protect FBG. Uniform metal coating can The optical fiber Bragg grating (FBG) sensor has great potential to be used for measuring temperature, strain, or even detecting fracture in metal materials. Embedding FBG sensor into metal materials is difficult and changing. Metal coating is one of the most efficient methods to protect FBG. Uniform metal coating can be applied in FBG sensor using electroless plating. The temperature changes induce thermal stress between the metal coating and the FBG due to their different thermal expansion coefficients. For the nickel-clad FBG, the thermal stress was analyzed and the math model about the coating thickness influencing temperature sensitivity was built. Temperature increase and decrease sensing experiment of the nickel-clad FBG shows, for increasing temperature and decreasing temperature, the errors between the practical temperature sensitivity coefficient and the model coefficient are 6.22% and 6.75% respectively. Compared with the naked FBG, the temperature sensitivity of the nickel-clad FBG is increased to two times and more. The results show the model is feasible to explain the temperature sensitivity enhancing mechanism..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 336 (2009)
Image Processing
Infrared Image Nonlinear Enhancement Algorithm Based on Contourlet Transform
Shi Dan, Li Qingwu, Ni Xue, and Huo Guanying
Considering the low contrast and strong noise of infrared images, an infrared image nonlinear enhancement algorithm based on Contourlet transform is proposed. As an efficient directional multiresolution image representation method, Contourlet transform can offer different number of directions at different scales. FirstConsidering the low contrast and strong noise of infrared images, an infrared image nonlinear enhancement algorithm based on Contourlet transform is proposed. As an efficient directional multiresolution image representation method, Contourlet transform can offer different number of directions at different scales. Firstly, Contourlet transform is performed on the original infrared image at different scales and directions, thus the low frequency subband coefficients and varieties of directional bandpass subband coefficients are obtained. Then, incomplete beta function is applied to enhance the image′s global contrast in the low frequency subband, and nonlinear gain function is used to process the coefficients at each scale in the directional bandpass subbands respectively, which suppresses small coefficients and enhances big coefficients by threshold denoising method. Finally, the enhanced infrared image is obtained by transforming these changed coefficients back to the spatial domain. The experimental results show that the algorithm proposed in this paper has advantages of enhancing low contrast infrared image efficiently over other methods, such as histogram equalization and wavelet transform enhancement. Our method can preserve more characteristics and reduce the noise of original image. It is superior to general histogram equalization and wavelet transform enhancement whatever in visual effect or in quantitative contrast parameter..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 342 (2009)
Characterization of Aero-Optic Effects and Restoration of Aero-Optical Degraded Images
Yang Wenxia, Cai Chao, Ding Mingyue, and Zhou Chengping
Computational analysis of the aero-optic effects caused by hyper-speed fluctuation fields was presented , and the blurred infrared image was restored. First, a time-averaged modulation transfer function (MTF) which represents the aero-optic effects was derived, experimental results show that the amplitude response of tComputational analysis of the aero-optic effects caused by hyper-speed fluctuation fields was presented , and the blurred infrared image was restored. First, a time-averaged modulation transfer function (MTF) which represents the aero-optic effects was derived, experimental results show that the amplitude response of the transmission function of the aero-optical effect can be characterized as a low-pass filter, which results in the blurring of the objects in the acquired infra-red images. The higher speed, the more serious image was blurred at the same flight height. Furthermore, the correctness of the theoretical MTF was evaluated by wind tunnel experiment. Finally, an adaptive Landweber iteration method was proposed to restore the blurred images, which updated the relaxation factors at each iteration. Experiments demonstrated that the method has higher convergence rate and better restoration effect..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 347 (2009)
Nonlinear Enhancement Algorithm for Infrared Image Based on Second Generation Wavelet Transform
Qin Hanlin, Zhou Huixin, Liu Shangqian, and Lu Quan
Because infrared image has the characteristics of low contrast and low signal-to-noise ratio, it is necessary to be enhanced. A second-generation wavelet transform based infrared image nonlinear enhancement algorithm is presented. The method is adopted to decompose the input infrared image, which extracts multi-scale dBecause infrared image has the characteristics of low contrast and low signal-to-noise ratio, it is necessary to be enhanced. A second-generation wavelet transform based infrared image nonlinear enhancement algorithm is presented. The method is adopted to decompose the input infrared image, which extracts multi-scale detail features of the image. Then, according to the difference between target and background noise signal, a fuzzy nonlinear enhancement operator is used to enhance the details of target feature intensity under different scale. Finally, the inverse transform of wavelet is applied to reconstruct image. The algorithm can avoid over-enhanced noise and raise image contrast. Compared with other several image enhancement algorithms, several groups of experimental results demonstrate that the presented algorithm enhance content information the infrared images target effectively..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 353 (2009)
Adaptive Algorithm for Image Denoising Based on Correlation Properties of Contourlet Coefficients
Yang Fan, Zhao Ruizhen, and Hu Shaohai
The contourlet coefficients corresponding to an image have strong correlations both at the same scale and between neighboring scales. Therefore, an adaptive threshold is firstly constructed by the intra-scale correlation property of contourlet coefficients. After the adaptive thresholding denoising, the inter-scale corThe contourlet coefficients corresponding to an image have strong correlations both at the same scale and between neighboring scales. Therefore, an adaptive threshold is firstly constructed by the intra-scale correlation property of contourlet coefficients. After the adaptive thresholding denoising, the inter-scale correlation of the contourlet coefficients is utilized to decide what processed coefficients to use. Based on the two above correlation properties of contourlet coefficients, a new adaptive contourlet-domain image deniosing algorithm is thus presented. The new algorithm cannot only remove noise thoroughly, but maintain the edges of the image effectively. Experimental results show that the proposed algorithm can get better denoising results and is superior to the available methods both visually and objectively..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 357 (2009)
Impact of Inhomogeneous Light Intensity on Test and Its Correction Method for Digital Speckle Interferometry with Substraction
He Dongsheng, Yang Dexing, Gu Bin, and Fang Zhiqiang
In digital speckle interferometry, inhomogeneous illumination on or reflection from a tested object will lead to inhomogeneous fringe pattern, and even make the fringe missing. On the basis of analyzing the principle of shearing speckle interferometry and assuming that principal value of speckle phase difference obeys In digital speckle interferometry, inhomogeneous illumination on or reflection from a tested object will lead to inhomogeneous fringe pattern, and even make the fringe missing. On the basis of analyzing the principle of shearing speckle interferometry and assuming that principal value of speckle phase difference obeys the uniform distribution between -π and π,a method for correcting the substracted fringe pattern modulated by uneven light intensity is proposed. This method is to construct a new function, which can eliminate background light intensity in small areas and remove the term modulated by light intensity. Thus, the fringe pattern becomes homogeneous. It is applied to shearing speckle interferometry to test a piece of aviation composite materials suffering strong impact, and the fringes which hide in dark areas are displayed. It shows the validity of this method to reduce the influence of uneven light intensity on speckle fringe pattern..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 362 (2009)
Imaging Systems
Research on Spectrum Plane Processing Technology of Target Auto-Recognition in Cluttered Scenes
Miao Hua, Zou Xin, Lang Qi, Chen Fanghan, and Wang Wensheng
Due to the low contrast, insufficient luminance of photographed images in cluttered scenes, the energy of correlation peaks is very weak. Sometimes even no correlation peaks appear when the hybrid optoelectronic joint transform correlator is used to detect and recognize targets. Therefore, the wavelet transform technolDue to the low contrast, insufficient luminance of photographed images in cluttered scenes, the energy of correlation peaks is very weak. Sometimes even no correlation peaks appear when the hybrid optoelectronic joint transform correlator is used to detect and recognize targets. Therefore, the wavelet transform technology used for the joint transform power spectrum (JTPS) is presented in this paper. The method effectively supresses the noise interference of JTPS, improves the energy of diffractive light carried useful information, and enhances the ability of detecting and recognizing targets in cluttered scenes by joint transform correlator. The experimental results prove that the energy of correlation peaks after processing the JTPS by wavelet transform is strenthened. As an example, the optical experimental results of the boat in lake are showed. It is obvious that the method is very feasible from experimental results..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 366 (2009)
Study on Four-Step Phase-Shifting Decoding Algorithm for Three-Dimensional Profilometry
Xie Jieru, and Cui Haihua
Accurate and efficient phase decoding algorithms play an important role in noncontact optical phase-measurement. This paper develops a new phase-shifting decoding algorithm based on analysis of the traditional method. At first, four-step phase-shifting method is used to get the unwrapping phase, The residues theory is Accurate and efficient phase decoding algorithms play an important role in noncontact optical phase-measurement. This paper develops a new phase-shifting decoding algorithm based on analysis of the traditional method. At first, four-step phase-shifting method is used to get the unwrapping phase, The residues theory is used to check the residues. Then a new reliability ordering map is used to guide to check rest of the residues. Low-pass filter algorithm is used to get the optimum check results. At last we place the branch cuts to balance all the residuals and decode the whold image by flood algorithm. Experimentations show that the proposed optical decoding algorithm is effective and robust..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 370 (2009)
Focal Depth of Fresnel Digital Holographic Imaging System
Wang Huaying, Zhao Baoqun, and Song Xiufa
Depth of focal (DOF) is an important parameter characterizing the performance of imaging system. Based on the criterion of the DOF of coherent lens imaging and by using numerical integration and computer simulations, the DOF of Fresnel digital holographic imaging system is deduced and analyzed. The corresponding expresDepth of focal (DOF) is an important parameter characterizing the performance of imaging system. Based on the criterion of the DOF of coherent lens imaging and by using numerical integration and computer simulations, the DOF of Fresnel digital holographic imaging system is deduced and analyzed. The corresponding expressions are compared with that obtained by the phase error criterion of ideal imaging. The results show that the DOF of Fresnel digital holographic system is different from that of coherent lens imaging system. With the definite recording distance and definite parameters of CCD, the DOF of off-axis Fresnel system is slightly larger than that of in-line system. Furthermore, the DOF of off-axis system with symmetrical reference offset is larger than that of the unsymmetrical one a little. The DOF obtained by image intensity criterion can be better characterized the performance of digital holographic imaging system..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 374 (2009)
Kalman-Filtering Nonuniformity Correction Algorithm Based on Nonlinear Model
Zhou Huixin, Wei Yajiao, Qin Hanlin, and Wang Bingjian
For resolving the influence that the nonlinear response of detectors imposed on the nonuniformity correction (NUC) for infrared focal plane arrays, a new improved Kalman-filtering nonuniformity correction algorithm with a nonlinear model is presented. In this algorithm, the nonlinear image data is translated into lineaFor resolving the influence that the nonlinear response of detectors imposed on the nonuniformity correction (NUC) for infrared focal plane arrays, a new improved Kalman-filtering nonuniformity correction algorithm with a nonlinear model is presented. In this algorithm, the nonlinear image data is translated into linearized one firstly, then the Kalman-filter NUC algorithm with a linear model is utilized to correct nonuniformity of the linearized image. Finally the exponents of the corrected linearized image data is calculated, and the uniformity image of the original one is achieved. Experimental results indicate that the presented algorithm not only inherits the advantage of the original algorithm, which resolves the problem of detector offset and gain drift with time by updating NUC parameters with information of the current scene, but also reduces the influence of the detector nonlinear response to the NUC performance in some degree, and acquires good NUC effect..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 378 (2009)
Theoretical Calculation and Design for Cylindrical and Conical Bent Crystal Spectrograph
Yang Qingguo, Li Zeren, Peng Qixian, Chen Guanghua, and Liu Shouxian
A basic theoretical calculation for the cylindrical and conical bent crystal spectrocgraph was done by using ray tracing method and the explicite formulations of the parameters for these spectrographs, such as spatial and spectral dispersion coordinates, linear and angular dispersion, spectral resolution, spatial and sA basic theoretical calculation for the cylindrical and conical bent crystal spectrocgraph was done by using ray tracing method and the explicite formulations of the parameters for these spectrographs, such as spatial and spectral dispersion coordinates, linear and angular dispersion, spectral resolution, spatial and spectral magnification, lominosity, were obtained. The two kinds of spectrographs are designed and their performace is compared. The results show that the conical bent crystal spectrograph is better than the same type of the cylindrical one on the focusing properties, which improves the efficiency of light gathering, luminosity and spatial resolution. This work provids a theoretical and design basis for the future manifacturing of spectrographs..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 382 (2009)
Instrumentation, Measurement and Metrology
Study on Optical Particle Measurement Based on Rainbow Phenomena
Pan Qi, and Wang Shimin
The parameter inverse problem of rainbow measurement was studied. The mathematic model was built and a novel inverse algorithm was presented which could simultaneously measure particle size and refractive index. The new algorithm removes noise using the technique based on empirical mode decomposition (EMD). A feature pThe parameter inverse problem of rainbow measurement was studied. The mathematic model was built and a novel inverse algorithm was presented which could simultaneously measure particle size and refractive index. The new algorithm removes noise using the technique based on empirical mode decomposition (EMD). A feature point extraction technique was presented and an optimal point search algorithm based on Debye theory was proposed which can rapidly find the relatively exact inversion parameter. Simulation results show that when the signal-to-noise ratio (SNR) drops to 5 dB, the maximum inversion error of diameter is less than 10％ and error of refractive index is less than 0.1％. A laboratory experiment was also taken which concentrated on detection of a rainbow formed by a free-falling raindrop at different temperature. The droplet was illuminated by a continuum laser with the wavelength of 532 nm and power of 14 mW. The rainbow light formed by the droplet was collected by a lens with large diameter and received by a linear CCD placed in the focus of the lens. The experimental results also show that the method is feasible and has a relatively good precision..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 388 (2009)
A Thermal Infrared Temperature and Emissivity Inversion Algorithm Based on Correction of Wien Approximation
Xu Zhou, and Zhao Huijie
Temperature and emissivity are the most important parameters in thermal remote sensing. A thermal temperature and emissivity separation algorithm based on Wien approximation and Alpha derived emissivity method (ADE) are proposed. This method corrected the Wien approximate based on the mathematical principle, and calculTemperature and emissivity are the most important parameters in thermal remote sensing. A thermal temperature and emissivity separation algorithm based on Wien approximation and Alpha derived emissivity method (ADE) are proposed. This method corrected the Wien approximate based on the mathematical principle, and calculated the spectral shape using ADE to identify the band which had the maximum and minimum emissivity, then deduced the relationship of each band’s emissivity after the correction of Wien approximate and derived the actual emissivity using this relationship and MMD model. For choosing better MMD model, this article compared the precision of two MMD model and applied the module which has higher precision in the algorithm. From the comparison with another method, the algorithm proposed here had higher precision and better stability. The inversion error of temperature is less than 1 K while which of emissivity is less than 0.015..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 394 (2009)
Large-Deformation Measurement Based on Reliable Initial Guess in Digital Image Correlation Method
Pan Bing, Xie Huimin, Xia Yong, and Wang Qiang
In order to measure large deformation using digital image correlation method, a new initial guess technique is presented. The proposed technique obtains the reliable initial deformation guess of the first calculation point by manually selecting three or more points with distinct characteristics surrounding the referencIn order to measure large deformation using digital image correlation method, a new initial guess technique is presented. The proposed technique obtains the reliable initial deformation guess of the first calculation point by manually selecting three or more points with distinct characteristics surrounding the reference subset center in the reference image and their corresponding locations in the deformed image. Then, reliable initial deformation guess can be determined according to the coordinate correspondence and is used as the iteration initial value of Newton-Rapshon method to further improve measurement accuracy. The proposed technique overcomes the shortcoming of the commonly used digital image correlation method which cannot work under the condition that the tested object has a rotation angle larger than seven degrees or large deformation. The measured displacement fields from image pairs with relative large rigid body rotation and large deformation compression test of polypropylene foam obviously demonstrate the validity of this technique..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 400 (2009)
A Mathematics Model for Aerosol Mass Measurement Using Light Scattering Counting Method
Yang Juan, Bian Baomin, Gu Fang, and Lu Jian
The general mathematics model for aerosol mass measurement by using the counting method is analyzed, and the result indicates that the total mass of aerosol can be expressed as linear addition of counting channels. The light scattering counting method for spherical particles mass measurement was studied as an example. The general mathematics model for aerosol mass measurement by using the counting method is analyzed, and the result indicates that the total mass of aerosol can be expressed as linear addition of counting channels. The light scattering counting method for spherical particles mass measurement was studied as an example. Starting with aerosol mass subset Ni, the fractal relation φ=Lβ between scattering luminous flux of counting channels and aerosol’s average volume can be gained according to statistics. Based on this, the general function (φj )≡ρj=ρL-ηφηj of average mass j and characteristic parameter φ of counting channels can be established, where η is the equivalent section fractal dimension with the range from 0 to 3. In further, all of these were extended to non-spherical particles mass measurement, and then the full mathematics model for aerosol mass measurement founded on light scattering counting method was established. This model provides a feasible way for the counter to measure aerosol mass concentration in real time..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 407 (2009)
Phase-Height Mapping Algorithm Based on Neural Network
Li Zhongwei, Wang Congjun, Qin Dahui, and Shi Yusheng
Establishing high precision phase-height mapping is one of the key techniques in structural light measurement system. Based on establishing accurate camera image and projector image correspondence, the three-layer back propagation neural network is trained to build a mapping relationship between image coordinates and tEstablishing high precision phase-height mapping is one of the key techniques in structural light measurement system. Based on establishing accurate camera image and projector image correspondence, the three-layer back propagation neural network is trained to build a mapping relationship between image coordinates and three-dimensional coordinates. A plane block with circle marks is used to collect sample data and train the neural network. In order to verify the precision of this algorithm, a standard sphere and a plaster model are measured using the trained network. The experimental results show that the algorithm proposed in this work can measure complex free-form surface objects. The measurement precision can achieve 0.095 mm..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 412 (2009)
An On-Line Phase Measuring Profilometry with Phase-Shifting Perpendicular to Moving Direction of Measured Object
Zhong Lijun, and Cao Yiping
A new method of on-line 3D measurement based on phase measuring profilometry(PMP) has been proposed. It only needs to ensure the phase-shift direction of the projected sinusoidal stripe perpendicular to the object′s moving direction. Though the spatial coordinates of the captured distorted stripe images by CCD are incoA new method of on-line 3D measurement based on phase measuring profilometry(PMP) has been proposed. It only needs to ensure the phase-shift direction of the projected sinusoidal stripe perpendicular to the object′s moving direction. Though the spatial coordinates of the captured distorted stripe images by CCD are inconsistent, by pixel matching algorithm, this inconsistency can be excluded, in addition, the equivalent phase-shifting distorted patterns needed by PMP can been obtained successfully. The profile of the measured object can be reconstructed which put the on-line 3D measurement into practice. A contrast experiment on a known plane inspected by the on-line PMP and the traditional static PMP is carried on, and the difference of mean square deviation between the two methods is only 0.007 mm,which shows the high veracity of the on-line PMP.A complex workpiece has also been on-line inspected, and the 3D profile of the workpiece can be reconstructed perfectly, which shows the feasibility and validity of the on-line PMP..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 417 (2009)
Lasers and Laser Optics
Effect of Laser Power on One-Dimensional Deposition of Chromium Atomic Beam
Zhang Baowu, Ma Yan, Li Tongbao, and Zhang Wentao
Deposition of collimated chromium (Cr) atomic beam focused by one-dimensional Gaussian standing-laser field with wavelength of 425.55 nm and powers of 3.93 mW and 40 mW is examined from particle-optics approach, using fourth-order Runge-Kutta algorithm with adaptive step size. The results show that the deposited structDeposition of collimated chromium (Cr) atomic beam focused by one-dimensional Gaussian standing-laser field with wavelength of 425.55 nm and powers of 3.93 mW and 40 mW is examined from particle-optics approach, using fourth-order Runge-Kutta algorithm with adaptive step size. The results show that the deposited structure has uniform periodicity along ox direction, while the structure quality has much difference along oy direction with different laser powers. When laser power is 3.93 mW, each nanoline is very clear, and the full width at half maximum (FWHM) is uniform in range of [-0.5, 0.5], where the unit is one laser waist radius, and the contrast is uniform in range of [-0.2, 0.2] along oy direction. When laser power is 40 mW, the nanostructure has three nano lines at the place where only one nanoline for 3.93 mW in range of [-1.08, 1.08] along oy direction. In addition, the structure in the plane of y=0 for 3.93 mW is similar to that in the plane of y=±1.08 for 40 mW, i.e. the average space is 212.78 nm, FWHM is 21.65 nm, and the contrast is 24.78. So the good deposited structure should correspond to suitable laser power..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 421 (2009)
Influence of the Bandwidth of Feedback Loop in Frequency Stabilization of External-Cavity Diode Laser by Polarization Spectroscopy
Wang Jing, Yang Baodong, He Jun, Zhao Jiangyan, Zhang Tiancai, and Wang Junmin
Based on the experiment of trapping single cesium atoms in magneto-optical trap (MOT), a grating-external-cavity diode laser, which provides the cooling/trapping beams of MOT is locked to cesium 6S1/2 F=4→6P3/2 F′=5 cycling transition by modulation-free polarization spectroscopy. This frequency locking method uses the Based on the experiment of trapping single cesium atoms in magneto-optical trap (MOT), a grating-external-cavity diode laser, which provides the cooling/trapping beams of MOT is locked to cesium 6S1/2 F=4→6P3/2 F′=5 cycling transition by modulation-free polarization spectroscopy. This frequency locking method uses the dispersion-like curve generated from polarization spectroscopy as frequency-discriminating signal. The error signal is feedback to both current modulation port of diode laser and voltage modulation port of piezoelectric transducer (PZT) in grating external cavity. The locking technique of modulation-free polarization spectroscopy can clearly improve the frequency stability compared with conventional saturation absorption spectroscopic technique. The minimum value of Allan variance is σy(τ) = 4.6×10-12 at average time of τ=300 s..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 425 (2009)
Simulation and Experimental Investigation on Coherent Beam Combination of Two Fiber Amplifiers Based on Stochastic Parallel Gradient Descent Algorithm
Zhou Pu, Liu Zejin, Ma Yanxing, Wang Xiaolin, Xu Xiaojun, and Guo Shaofeng
Numerical simulation on coherent beam combination of multiple fiber amplifiers based on stochastic parallel gradient descent (SPGD) algorithm is carried out. Coherent beam combination of two watt-level fiber amplifiers is experimentally achieved. Phase controlling is performed by SPGD algorithm. The whole system in cloNumerical simulation on coherent beam combination of multiple fiber amplifiers based on stochastic parallel gradient descent (SPGD) algorithm is carried out. Coherent beam combination of two watt-level fiber amplifiers is experimentally achieved. Phase controlling is performed by SPGD algorithm. The whole system in close-loop performs well. The probability of energy encircled in the target pinhole to be more than 80% of its ideal value is increased from 27.7% to 70.3%, and the energy encircled in the pinhole is enhanced by a factor of 1.57 when the system evolves from open loop to close loop. The feasibility of coherent combination of high-power fiber amplifiers using the method proposed is also discussed..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 431 (2009)
Real-Time Mode Hopping Detection on Narrow Line-Width Laser Source Based on Unbalanced Fiber Interferometer
Liang Xun, Yao Qiong, Hu Yongming, Xiong Shuidong, Hu Zhengliang, and Rao Wei
Random mode hopping in narrow line-width lasers is a significant factor that affects the stability of the optical system. Narrow line-width lasers always have long resonantor length and small intervals between two neighbor modes. A new method of detecting mode hopping based on unbalanced fiber interferometer for very nRandom mode hopping in narrow line-width lasers is a significant factor that affects the stability of the optical system. Narrow line-width lasers always have long resonantor length and small intervals between two neighbor modes. A new method of detecting mode hopping based on unbalanced fiber interferometer for very narrow line-width laser is proposed. It transforms the mode hopping process to the phase change of the unbalanced interferometer. Phase generated carrier (PGC) modulation-demodulation technique has been used to detect the phase signal. This method has high sensitivity and can be used in long time and real-time observation with better effects than Fabry-Perot interferometer. It can also be used in measuring the line-width (～kHz) of the laser, and gives a good testing method to improve the performance of the laser source..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 437 (2009)
Materials
Magnetic-Optics Effect of Nematic Liquid Crystal in Weak Magnetic Field
Chen Ting, and Feng Shimeng
The structure of twisted namatic liquid crystal does not change under weak magnetic field. The rotation of polarization of light in the twisted nematic liquid crystal with the applied weak magnetic field is analyzed using the dielectric rate tensor. The theoretical results show that linearly polarized light transmittinThe structure of twisted namatic liquid crystal does not change under weak magnetic field. The rotation of polarization of light in the twisted nematic liquid crystal with the applied weak magnetic field is analyzed using the dielectric rate tensor. The theoretical results show that linearly polarized light transmitting this liquid crystal can produce left-hand and right-hand elliptically polarized light, which corresponds to the different speed of propagation. This leads to the rotation of polarization of light when it passes through this liquid crystal. A method to calculate rotation angle which results from the combination of the left-hand and right-hand elliptically polarized light is given. The dependence of the transmitted ratio of light on the applied magnetic field is founded. Under the same wavelength of light, the more intense the magnetic field strength, the larger the rotated angle of polarization of light. At the same magnetic field strength, The shorter the wavelength of light, the larger the rotated angle of polarization of light. When the directors of liquid crystal are parallel to the direction of the magnetic field, the polarization rotation of light can also been observed..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 443 (2009)
Theoretical Calculation of Electronic Structures and Optical Properties of YTaO4 and LuTaO4
Xiang Dong, Liu Bo, Gu Mu, Liu Xiaolin, Huang Shiming, and Ni Chen
Electronic structures, dielectric functions, refraction indices, absorption spectra of perfect YTaO4 and LuTaO4 crystals are calculated using pseudo-potentials and plane waves based on first-principles method. The results show that valence bands of YTaO4 and LuTaO4 are both from O2p states. Conduction band is divided iElectronic structures, dielectric functions, refraction indices, absorption spectra of perfect YTaO4 and LuTaO4 crystals are calculated using pseudo-potentials and plane waves based on first-principles method. The results show that valence bands of YTaO4 and LuTaO4 are both from O2p states. Conduction band is divided into two parts. The lower conduction band is mainly composed of Ta5d states and the upper conduction band involves contribution mainly from Y4d states of YTaO4 and Lu5d states of LuTaO4. When ω equals to zero, the dielectric constants and refractive indices between YTaO4 and LuTaO4 are close to each other. The low-energy characteristic peaks below 10.0 eV of their imaginary parts originate from the electron transition within TaO3-4 complex. The low-energy characteristic peaks between 10.0 eV and 15.0 eV correspond to the electron transition from valence band to the upper conduction band. The peaks beyond 15.0 eV are due to the electron transition from O2s to conduction band. Last but not the least, the ultraviolet absorption bands of YTaO4 and LuTaO4 are broad and strong. They correspond to the charge transfer transition from oxygen (2p) to d0 ion of tantalum..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 448 (2009)
Second Harmonic Generation and Effect Factors in Silica Photonic Crystal Waveguide
Shi Jianping, Dong Kexiu, Huang Yuan, Yang Shurong, and Chen Xunan
Silicon is one of important semiconductor materials in micro-fabrication technology. However it belongs to m3m point group, there is no second harmonic generation (SHG) in it. This is an obstacle for the integration of nonlinear micro-structures in optical system on chip. We present the silicon waveguide structure baseSilicon is one of important semiconductor materials in micro-fabrication technology. However it belongs to m3m point group, there is no second harmonic generation (SHG) in it. This is an obstacle for the integration of nonlinear micro-structures in optical system on chip. We present the silicon waveguide structure based on photonic crystals to realize SHG and overcome the technology bottle-neck. The configuration of waveguides and the basic principle are put forward. The computation model and methods based on finite difference time domain (FDTD) are given. Finally we present a design result aimed at the wavelength of 10.6 μm and analyze the SHG. The results show the enhancing electric quadrupole polarization leads to the SHG in silicon by virtue of photonic band edge effect. Under the condition of perfect phase matching, the conversion efficiency is 0.2% at the pumping power of 1.3 MW/mm2. At the end, effect factors of conversion efficiency are discussed briefly..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 506 (2009)
Low Loss Arc Fusion Splice of Photonic Crystal Fibers
Guo Tieying, Lou Shuqin, Li Honglei, Yao Lei, and Jian Shuisheng
A fusion scheme is proposed for achieving low-loss splice between photonic crystal fiber (PCF) and single-mode fiber(SMF) using conventional arc fusion splicer. Experimental measurements and theoritical calculations are both involved in this sheme. Firstly, how PCF′s air-hole structures varied along with the applied fuA fusion scheme is proposed for achieving low-loss splice between photonic crystal fiber (PCF) and single-mode fiber(SMF) using conventional arc fusion splicer. Experimental measurements and theoritical calculations are both involved in this sheme. Firstly, how PCF′s air-hole structures varied along with the applied fusion power was observed by changing fusion parameters, such as fusion time and current. Then the mode distributions at the fiber tips and the corresponding splice loss between the two fibers were calculated, and the fusion power range for low splice loss was thus deduced. In return, the optimal sets of fusion splice parameters were determined and low-loss high-strength splicing between the PCF and SMF was achieved. The uncertainties, like the extent of hole contraction of the PCF and its effect on the matching between the two fibers are cleared up in this sheme. Also, the fusion efficiency and quality are both improved owing to the scheme′s effectivity in determining an optimized set of fusion parameters for splicing PCF to SMF..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 511 (2009)
Medical Optics and Biotechnology
A New Method of Caries Diagnosis Based on Fluorescence Spectrum
Tang Jing, Liu Li, and Li Songzhan
A new caries detection method of fluorescence spectrum which contains backscattering, back-reflected and auto-fluorescence is proposed after researching on the interaction mechanism of laser with dental tissue and relationship between remitted light and optical properties of the tissue. Not only auto-fluorescence but aA new caries detection method of fluorescence spectrum which contains backscattering, back-reflected and auto-fluorescence is proposed after researching on the interaction mechanism of laser with dental tissue and relationship between remitted light and optical properties of the tissue. Not only auto-fluorescence but also back-reflected and back-scattering were produced in the process of the interaction. All of these lights contained rich information related with caries components, structure, spatial conformation, and so on. In order to obtain the relationship between those information and various stages of dental caries, an experiment of caries in vitro was designed and carried out. Investigation was performed on 104 samples by using He-Ne laser (λ=632.8 nm,2.0±0.1 mW) as a source of probing radiation. Using the Rayleigh scattering to normalize the intensity of measured spectrum, we defined anti-Stoke′s scattering normalization coefficient C1, which can describe morphological changes in dental tissue, and Stoke′s fluorescence normalization coefficient C2, which can describe chemical changes in tooth, and then, we evaluate various stages of dental caries by analyzing two normalization coefficient of caries characteristic spectrum. Preliminary results showed a high potential of using this new method to diagnose various stages of dental caries, and it is more sensitive to white caries, filling and Dental calculus..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 454 (2009)
The Radial Basis Function Neural Network Quantitative Analysis Model for Determination of Anti-tuberculosis Tablets Using Near Infrared Spectroscopy
Lu Jiahui, Wang Di, Shen Wei, Guo Weiliang, Zhang Yibo, and Teng Lirong
A new approach is established to determine the contents of rifampicin (RMP), isoniazide (INH) and pyrazinamide (PZA) in five varieties of anti-tuberculosis tablets,i.e. rifampicin tablets, isoniazide tablets, pyrazinamide tablets, rifampicin and isoniazide tablets and rifampicin isoniazide and pyrazinamide tablets. NeaA new approach is established to determine the contents of rifampicin (RMP), isoniazide (INH) and pyrazinamide (PZA) in five varieties of anti-tuberculosis tablets,i.e. rifampicin tablets, isoniazide tablets, pyrazinamide tablets, rifampicin and isoniazide tablets and rifampicin isoniazide and pyrazinamide tablets. Near infrared spectroscopy (NIRS) with radial basis function neural network (RBFNN) is applied to establishing the analytical protocol for the determination of the contents of RMP, INH and PZA in the five anti-tuberculosis tablets. The root mean square error of calibration set obtained by cross-validation (RMSECV) is used as the evaluation of the model. The optimal quantitative analysis models are resulted from selecting the most effective spectral region,suitable topological parameter and spread constants. RMSECV of the optimum models are 0.0127, 0.0104 and 0.0078. Using these optimum models for determination of the RMP, INH and PZA contents in prediction set, the root mean square error of prediction set (RMSEP) are 0.0125, 0.0109 and 0.0103. Internal cross-validation and external validation are verified and the method has a high accuracy and can meet the accuracy in simultaneous determination of RMP, INH and PZA contents in 5 varieties of anti-tuberculosis tablets..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 459 (2009)
Nonlinear Optics
Effect of Adiabatic Dust Charge Fluctuation On Three-Dimensional Solitary Waves In Inhomogeneous Dusty Plasmas
Zhang Xijun, and Wang Jizeng
In reality the charge on the dust grain varies both with space and time due to the electron and ion current flowing into or out of the dust grain, as well as other processes like secondary emission,photoemission of the electrons and etc.The dust charge fluctuation would be important for studying the behavior of dusty pIn reality the charge on the dust grain varies both with space and time due to the electron and ion current flowing into or out of the dust grain, as well as other processes like secondary emission,photoemission of the electrons and etc.The dust charge fluctuation would be important for studying the behavior of dusty plasmas.Today the study to non-linear wave in inhomogeneous dusty plasmas is focused on one-dimensional and it is very small to three-dimensional.A modified variable coefficients Korteweg-de Vries (MKdV) equation is derived by using the reductive perturbation method with the inhomogeneity, the dust charge fluctuation,the dust temperature, and the external magnetic field.The results show the inhomogeneity, the dust charge fluctuation,the dust temperature,and the external magnetic field influence the propogation of three-dimensional nonlinear waves. The approximate analytical solution is obtained by using approprate transform..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 464 (2009)
Special Group-Velocity Mode in Process of Third-Harmonic Generation of Ultrashort Pulses
Yang Yisheng, Han Wei, Tan Jichun, Zheng Wanguo, Cao Dingxiang, Xiang Yong, Li Fuquan, Li Keyu, Jia Huaiting, Wang Liquan, Feng Bin, and Zhong Wei
Based on the nonlinear coupling equations, conversion properties (i.e. efficiency and bandwidth) of third-harmonic generation (THG) of ultrashort pulses in different special group-velocity modes are analyzed. The THG mixing process of ultrashort pulses (FWHM～150 fs) in Type-I KDP crystals is simulated by using split-stBased on the nonlinear coupling equations, conversion properties (i.e. efficiency and bandwidth) of third-harmonic generation (THG) of ultrashort pulses in different special group-velocity modes are analyzed. The THG mixing process of ultrashort pulses (FWHM～150 fs) in Type-I KDP crystals is simulated by using split-step Fourier transformation and fourth-order Runge-Kutta method. Obtained results show that THG conversion properties (conversion efficiency being 50% and frequency bandwidth up to 2 nm) in the “three-wave-packet unequal velocity-mode” are better than those in other group-velocity modes. The conclusion provides theoretical guiding for further improving the THG efficiency and bandwidth of ultrashort pulses..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 468 (2009)
Optical Design and Fabrication
Probe Inducing Surface Plasmon Resonance Nanolithographic System
Zhao Chengqiang, Xu Wendong, Hong Xiaogang, Li Xiaogang, and Tang Xiaodong
A probe inducing surface plasmon resonance nanolithographic (PSPRN) system is introduced, which is constructed based on an atomic force microscope (AFM). Not only this system has realized accurate control of the probe, but the system itself has the complete function of AFM, it may examine surface appearance of the sampA probe inducing surface plasmon resonance nanolithographic (PSPRN) system is introduced, which is constructed based on an atomic force microscope (AFM). Not only this system has realized accurate control of the probe, but the system itself has the complete function of AFM, it may examine surface appearance of the sample and the lithography effect in real time. The advanced Kretschmann resonance coupled device with index-matching oil between the prism and the substrate is used in this system, which makes the replacement of samples easier. Acousto-optic modulator combined with AFM is adopted to realize the accurate control of the irradiation time of plasma-excited laser. In preliminary experiment, lithographic spots with about 100nm in diameter are obtained on silver film, which has confirmed the feasibility of PSPRN. The effects of illumination time, laser power, material thickness, laser incident angle etc. on size and depth of lithography spots are studied, which provide reference for the realization of smaller lithographic spots..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 473 (2009)
Design of 8× Uncooled Thermal Infrared Hybrid Refractive-Diffractive Continuous-Zoom Lenses
Xu Liang, Zhang Guoyu, Gao Yujun, Yang Fei, and Fan Fan
A set of 8～12 μm infrared (IR) hybrid refractive-diffractive continuous zoom lenses is designed,based on long-wave 320×240 element uncooled thermal IR focal plane arrays (FPA) detector. The continuous zoom system has a large relative aperture,the F# is 1.3, and the zoom ratio is 8. Ge and ZnS are used in the contiA set of 8～12 μm infrared (IR) hybrid refractive-diffractive continuous zoom lenses is designed,based on long-wave 320×240 element uncooled thermal IR focal plane arrays (FPA) detector. The continuous zoom system has a large relative aperture,the F# is 1.3, and the zoom ratio is 8. Ge and ZnS are used in the continuous zoom system. A diffractive surface and an aspheric surface are used for correcting the system color aberration and off axis aberration. The modulation transfer function (MTF) is above 0.5 in all focal distance at the spatial frequency of 18 lp/mm, and the MTF approaches the diffraction limit. The energy permeance ratio is greater than 78% when the system receiving radius in the detection sensor is smaller than 17.5 μm, which shows that the imaging quality of the continuous zoom system is very good..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 478 (2009)
Investigation of Performance on Trough Concentrating Solar Photovoltaic/Thermal System Based on Super Cells
Xiang Ming, Li Ming, Wang Liuling, He Jianhua, Li Chengqin, Xu Yongfeng, Zhang Xinhua, and Wang Yunfeng
A mathematic model of a trough concentrating solar PV/T system has been established and verified with experimental data. The calculation based on the model is agreeable with experimental results, the errors between calculations and experiments are less than 5%, which indicates that the model is valid. Through the modelA mathematic model of a trough concentrating solar PV/T system has been established and verified with experimental data. The calculation based on the model is agreeable with experimental results, the errors between calculations and experiments are less than 5%, which indicates that the model is valid. Through the model, the performance of the trough concentrating solar PV/T system based on super cells is analyzed systematically with internal and external parameters of PV/T system. The internal parameters include optical efficiency of mirror, width of focusing line, thermal conductivity of heat sinking tape and thermal absorption of the lighting plate, while the external parameters include the wind speed and the solar direct radiation. A large number of simulations were undertaken to test the thermal, electricity, total and exergy efficiency of PV/T system for variation of the design parameters. The result indicates that the optical efficiency of mirror has more effect on the performance of system than others, the total and exergy efficiency increase 0.9 times and 0.5 times respectively with the optical efficiency of mirror increasing from 0.5 to 0.95. Other parameters also have strong effects on the performance of system. All these works benefit to further study in optimization design of the system..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 482 (2009)
Optical Devices
Application of Hartmann-Shack Sensor in Optical Readout System of Uncooled Infrared Imaging
Ma Xiaoyu, Fan Zhihua, Rao Changhui, Qian Jian, and Shi Haitao
An optical readout system based on Hartmann-Shack sensor is introduced. This system uses Shacke-Hartmann wavefront sensor (SHWS) to detect the wavefront gradient variance of focal-plane array (FPA) cell before and after being heated and then reconstructs the IR image of object being detected. After vividly discussing iAn optical readout system based on Hartmann-Shack sensor is introduced. This system uses Shacke-Hartmann wavefront sensor (SHWS) to detect the wavefront gradient variance of focal-plane array (FPA) cell before and after being heated and then reconstructs the IR image of object being detected. After vividly discussing its imaging capability theoretically, we obtain the infrared image of a high-temperature object with cell size 60 μm×60 μm and array size 34 pixel×38 pixel in experiment. Its noise equivalent temperature difference (NETD) is about 3.8 K. If system parameters are optimized, the measurement accuracy of SHWS for arriving angles can be improved and thus smaller NETD can be attained..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 490 (2009)
OPTOELECTRONICS
Photo-Ionization Effects in High Gain Gallium Arsenide Photoconductive Semiconductor Switches
Liu Hong, and Ruan Chengli
The photo-ionization effects in high gain intrinsic gallium arsenide (GaAs) photoconductive semiconductor switches (PCSS) are explored. In high gain GaAs PCSS, each stage in which the streamer is formed consists of photo-ionization and domain electron avalanche (DEA) and avalanche carrier growth. Photo-ionization effecThe photo-ionization effects in high gain intrinsic gallium arsenide (GaAs) photoconductive semiconductor switches (PCSS) are explored. In high gain GaAs PCSS, each stage in which the streamer is formed consists of photo-ionization and domain electron avalanche (DEA) and avalanche carrier growth. Photo-ionization effects create a local high carrier density region in which a local environment for the existence of the domain is provided. Photo-ionization effects include the laser trigger and recombination radiation originating from streamer. The optimum condition of optical trigger is discussed. It is computed that the recombination radiation produces excess carriers around streamer inside a local region about y≤30 μm and the product of average carrier density n(t=0) times characteristic length y is larger than 1012 cm -2, namely n(t=0)·y>1012 cm- 2. The characteristics of photoionization effects of streamer are investigated. The space threshold LEC (in the direction of electric field) of trigger region is found. The characteristic length LE of trigger region must be larger than LEC, namely LE>LEC..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 496 (2009)
Tetrapod-Like Nano ZnO Field Emission Display with Triode Structure
Lin Zhixian, and Guo Tailiang
The diode field emission display (FED) has high driving voltage, which brings trouble to driving circuit. In order to solve this problem, we design normal grid triode structure tetrapod-like nano-ZnO FED. The field emission property is investigated. The results show that the structure is feasible. With abrasive blastinThe diode field emission display (FED) has high driving voltage, which brings trouble to driving circuit. In order to solve this problem, we design normal grid triode structure tetrapod-like nano-ZnO FED. The field emission property is investigated. The results show that the structure is feasible. With abrasive blasting and lithographic technology, grid apertures of the normal grid structure have been created, and low voltage control is achieved. The grid voltage, the gate apertures size and the thickness of medium layer parameters which influence the performance of triode FED have been analyzed. The experimental results show that normal gate triode-structure tetrapod-like nano-ZnO FED has well electron emission performance and it is also a potential field emission display..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 500 (2009)
Physical Optics
Analysis of Interference of Planar Vortex Beams
Wang Hao, Yang Dexing, Gan Xuetao, Zhao Jianlin, Ren Xiaoyuan, and Jiang Hongzhen
The interference of several optical vortices can generate intriguing intensity and phase distributions due to the particular helical phase structures and central singularities. The interference of optical planar vortex, which has a phase singularity and a dark hole nested in an infinite plane-wave background, is simulaThe interference of several optical vortices can generate intriguing intensity and phase distributions due to the particular helical phase structures and central singularities. The interference of optical planar vortex, which has a phase singularity and a dark hole nested in an infinite plane-wave background, is simulated. The influences of the distances between the singularities and the topological charges of two planar vortices on the annihilations and creations of vortices are analyzed, respectively. Further, the interference of the symmetric point vortices is investigated numerically. The results show that a rich variety of the symmetric vortex arrays can be obtained by changing the number of the vortices and/or the topological charges. The interference of the symmetric point vortices is demonstrated experimentally by utilizing computer-generated holography and spatial light modulator. The experimental results are in good agreement with those of numerical simulation. It not only confirms the numerical results, but also demonstrates a convenient way of generating interference of complex optical vortices..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 517 (2009)
Quantum Optics
Research on Property of Interference Pattern for Bose-Condensed Gas in One-Dimensional Optical Lattice
Xu Zhijun, Li Penghua, and He Fang
An array of condensations trapped in one-dimensional (1D) optical lattice is used as a source of coherent matter wave to investigate the coherence properties of the Bose-einstein condensates (BEC). The macrowave function for matter wave interference is given. Based on the wave function, the distribution of particle numAn array of condensations trapped in one-dimensional (1D) optical lattice is used as a source of coherent matter wave to investigate the coherence properties of the Bose-einstein condensates (BEC). The macrowave function for matter wave interference is given. Based on the wave function, the distribution of particle number density, particle current density, velocity of interference peak movement and phase of the macrowave function were studied. The evolution of the interference pattern under a varible relative phase difference between successive optical lattice sites is also discussed. The research shows that the peak of interference is a wave packet with a fixed velocity, the wavelength satisfies the relation of de Broglie, and the evolution of the wave packet phase can be approximated by the classical plane wave..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 523 (2009)
Rapid Communications
Two-Dimensional Imaging Experiment of a Point Target in a Laboratory-Scale Synthetic Aperture Imaging Ladar
Zhou Yu, Xu Nan, Luan Zhu, Sun Jianfeng, and Liu Liren
The 2D imaging in both the azimuth and the range directions of a point target is realized in our laboratory-scale synthetic aperture imaging ladar setup. The experimental results are identical with the predicted.The 2D imaging in both the azimuth and the range directions of a point target is realized in our laboratory-scale synthetic aperture imaging ladar setup. The experimental results are identical with the predicted..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 566 (2009)
Spectroscopy
Stark Broadening Spectral Line Profile at Different Electric Microfield Distribution Functions
Ran Junxia, Zhang Shaopeng, Li Honglian, Hao Xiaohui, and Pang Xuexia
The Stark broadening spectral line profile is described at different electric microfield distribution functions. According to Stark broadening theory, Stark broadening spectral line profile is asymmetry in essence considering plasma ions impact. The electric microfield distribution function is very important for the spThe Stark broadening spectral line profile is described at different electric microfield distribution functions. According to Stark broadening theory, Stark broadening spectral line profile is asymmetry in essence considering plasma ions impact. The electric microfield distribution function is very important for the spectral line profile. The results show that the Stark broadening spectral line profile is similar at the Holtsmark distribution and Nearest-Neighbor field distribution and it is diversification at Mayer model. With the decreasing of the electrons impact broadening parameter, the influences of different electric microfield distribution functions are diminished. With the decreasing of the plasma ions impact parameter, the influences of different electric microfield distribution functions are trailing off. The results also show that the action of electric microfield distribution functions is similar when the plasma ions impact parameter is very small. It is illuminated that the plasma ions intense impact has great influence on the spectral line profile..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 529 (2009)
Study on Tea and its Principal Components by Infrared Spectroscopy
Zhao Xiaohui, Nie Zhichu, Zhang Lianshui, Zhang Rongxiang, and Li Xiaowei
It is important for tea trade of China to improve a method of rapid tea identification. Infrared spectroscopy is used to study the tea based on their “finger character” in the spectral region of 800～3800 cm-1. Four kind of brand tea in China and its principal components have been studied, including Biluochun tea and TiIt is important for tea trade of China to improve a method of rapid tea identification. Infrared spectroscopy is used to study the tea based on their “finger character” in the spectral region of 800～3800 cm-1. Four kind of brand tea in China and its principal components have been studied, including Biluochun tea and Tieguanyin tea from different areas, caffcine, epicatechin, glutamic acid and anthocyanic. Contents of components in different kind of tea have been obtained by principal component model analysis from their middle infrared spectroscopy. The results show that the difference among these tea are revealed from the relative content of principal components. The distinguish between Biluochun tea and Tieguanyin tea exhibit the content of effective component, which the former has lower content. Meanwhile, the distinguish among the same kind of tea from different producing area mainly exhibit relative content of epicatechin and caffcine, which tea from original area has relatively higher content. These conclusion has verified the possibility of tea identification by spectral method and has great help for rapid tea identification..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 533 (2009)
Variety Discrimination of Grapes Based on Visible-Near Reflection Infrared Spectroscopy
Cao Fang, Wu Di, He Yong, and Bao Yidan
A non-destructive method for discriminating varieties of grapes by visible and near reflection infrared spectroscopy (VIS-NIRS) was developed. The spectral data of three varieties of grape samples were clustered by principal component analysis (PCA). The results indicate that Heiti grape sample can be totally separatedA non-destructive method for discriminating varieties of grapes by visible and near reflection infrared spectroscopy (VIS-NIRS) was developed. The spectral data of three varieties of grape samples were clustered by principal component analysis (PCA). The results indicate that Heiti grape sample can be totally separated from the other two. Mainaizi and Mulage grape samples were discriminated based on back propagation-neural networks (BP-NN) model. The three hidden-layer BP-NN model was built with the first ten PCs as inputs, and the dummy variety numbers of grapes as outputs. The correct answer rate 98.28 % of BP-NN model is achieved, which is better than the one achieved by the soft independent modeling of class analogy(SIMCA) method. Four effective wavelengths for variety discrimination are 453,493,542 and 668 nm. The correct answer rate of BP-NN model based on the spectra of effective wavelengths is 97.41 %.The result indicates that variety discrimination of grapes can be achieved rapidly and non-destructively by using VIS-NIRS with PCA and BP-NN..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 537 (2009)
Application of Near Infrared Spectroscopy in Process Analysis of TCM Manufacturing
Nie Lixing, Wang Gangli, Li Zhimeng, and Lin Ruichao
Qualitative and quantitative methods for analysis of raw materials of Tongren Wuji Baifeng Wan were developed by near infrared spectroscopy(NIRS) in combination with several chemometrics methods. Standard NIR spectral libraries of raw materials were constructed, based on which the unknown materials were verified by quaQualitative and quantitative methods for analysis of raw materials of Tongren Wuji Baifeng Wan were developed by near infrared spectroscopy(NIRS) in combination with several chemometrics methods. Standard NIR spectral libraries of raw materials were constructed, based on which the unknown materials were verified by quality control(QC) comparison search. Discriminant analysis based on principle component analysis (PCA) and Mahalanobis distance was used in identification of pullus cum Osse Nigko. The spectra of semi-products were used as the standard database for negative semi-product screening by similarity match. Calibration models for assay of main raw materials, excipients, semi-product and finished product were built by partial least squares (PLS) regression , respectively. A revolutionary miniature NIR blend analyzer was used for on-line endpoint prediction in blending process of semi-product based on moving window standard deviation. It is proved that the qualitative methods can distinguish samples accurately while the quantitative methods were precise and reliable. The proposed methods are fast, simple and environmental-friendly, and can be applied to at-spot detection in industrial field by at-line or on-line control..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 541 (2009)
Double FBG System for Acetylene Sensing Based on Differential Absorption Spectroscopy
Ding Hui, Liang Jianqi, and Xiong Zhihui
A differential absorption system based double fiber Bragg gratings(FBG) system for sensing acetylene is proposed. In this system the reflected light from FBG is used as the probing light to detect acetylene. By the introduction of a reference FBG, the noise from the light path is reduced greatly, so that the weak respoA differential absorption system based double fiber Bragg gratings(FBG) system for sensing acetylene is proposed. In this system the reflected light from FBG is used as the probing light to detect acetylene. By the introduction of a reference FBG, the noise from the light path is reduced greatly, so that the weak responding signals buried in the strong background signal can be picked out. Furthermore, by using digital filter, undesirable low-frequency periodic interference in the collected signal is removed, which makes the system more reliable and stable. The experimental results show that the system has high sensing sensitivity in detecting acetylene and the lowest detection limit is 25×10-6. The proposed system has great potential for developing multi-gas sensing system in the future research work..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 548 (2009)
Thin Films
Second-Order NLO Properties of Hybrid Films Covalently Incorporated with Aryl-Donor Type Chromophore
Chen Lujian, Wei Dong, Wang Xiaozhong, Cui Yuanjing, and Qian Guodong
To meet the thermal stability requirement for electro-optic device application, a new hybrid second-order NLO film is successfully prepared from chromophore with aryl-donor and examined by atom force microscope (AFM). The hybrid films exhibites good optical nonlinearity (d33 is 14.1 pm/V). The d33 value of the film hasTo meet the thermal stability requirement for electro-optic device application, a new hybrid second-order NLO film is successfully prepared from chromophore with aryl-donor and examined by atom force microscope (AFM). The hybrid films exhibites good optical nonlinearity (d33 is 14.1 pm/V). The d33 value of the film has an onset temperature around 115 ℃ and a half-decay temperature at 145 ℃. The distributions of d33 on hybrid films on different substrates are also analyzed after corona poling. The measurement of NLO films on ITO substrates presents some advantages over normal glass substrates..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 552 (2009)
Preparation of ZrO2/SiO2 Antireflective Hard Coating from Sol-Gel Processing
Li Haiyuan, Tang Yongxing, and Hu Lili
A type of quarter-wavelength two-layer antireflective hard coating has been developed by sol-gel dipping method with zirconium n-propoxide [Zr(OPr)4] and tetraethoxysilane (TEOS) as precursors. The coating possesses smooth and even surface, its root-mean-square rouhness is 1.038 nm and the average roughness is 0.812 nmA type of quarter-wavelength two-layer antireflective hard coating has been developed by sol-gel dipping method with zirconium n-propoxide [Zr(OPr)4] and tetraethoxysilane (TEOS) as precursors. The coating possesses smooth and even surface, its root-mean-square rouhness is 1.038 nm and the average roughness is 0.812 nm. For the silica glass substrate with two sides coated with the above coating, the transmittance at 351 nm, the third harmonic of 1053 nm, is 99.41%, which is improved by 6.14% than that of the uncoated material. For the double-side-coated K9 substrate, the transmittance at 1053 nm is about 99.63%, which is improved by 7.67%. The laser damage threshold of the coating is 16.8 J/cm2, for 1053 nm wavelength and 1 ns pulse width. The coating has well antireflective and scratch-resistant performance, as well as high damage threshold..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 556 (2009)
Selecting Energy Density for Laser Preconditioning Optical Films
Xia Zhilin, Zhao Yuan′an, Huang Caihua, Shao Jianda, Xue Yiyu, Yang Fangfang, and Guo Peitao
Frequency-tripled Nd∶YAG laser was used to pre-treat optical film samples. The capacity of optical film′s resisting laser induced damage is affected by laser preconditioning, but the influence regulations are very complicated. Results reflect that appropriate pre-treating laser energy density is related to testing laseFrequency-tripled Nd∶YAG laser was used to pre-treat optical film samples. The capacity of optical film′s resisting laser induced damage is affected by laser preconditioning, but the influence regulations are very complicated. Results reflect that appropriate pre-treating laser energy density is related to testing laser energy density. From the aspects of laser annealing and laser induced slight damage in pre-conditioning, the probability statistical model of laser-induced damage deduced by the author can explain these complicated phenomena well. Generally, if the energy density of preconditioning laser pulse is below the critical energy density for laser annealing, the effect of laser precondition is negative mostly; when the energy density of preconditioning laser pulse is beyond the critical energy density for laser anneal and below that for laser induced micro-damage, the effect of laser precondition is positive mainly. It is appropriate to choose the preconditioning pulse energy density in this scope; while if the energy density of preconditioning laser pulse is beyond the critical energy density for laser induced micro-damage, the effect of laser precondition is negative mainly..
Acta Optica Sinica
- Publication Date: Jun. 19, 2020
- Vol. 29, Issue 2, 560 (2009)
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