Journals >Acta Photonica Sinica
Contents
2016
Volume: 45 Issue 12
24 Article(s)
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Research Article
Theoretical Study on the Valence-shell Photoionization of Na Atoms and Na-like Fe15+ Ions
LIU Xiao-bin, SHI Ying-long, XING Yong-zhong, LU Fei-ping, and CHEN Zhan-bin
Calculations of photoionization cross sections for Na atoms and Na-like Fe15+ ions were carried out in the framework of relativistic multiconfiguration Dirac-Fock method. For Na atoms, comparisons were made with previous theoretical calculations and available experimental measurements and a good or at least reasonable Calculations of photoionization cross sections for Na atoms and Na-like Fe15+ ions were carried out in the framework of relativistic multiconfiguration Dirac-Fock method. For Na atoms, comparisons were made with previous theoretical calculations and available experimental measurements and a good or at least reasonable agreement is found if the relativistic and relaxation effects are taken into account. It is shown that, for the outermost valence electrons of medium Fe15+ ions, the relativistic effects accounts for a prominent part in the photoionization process and orbital relaxation can be negligible; however it is not the same case for neutral Na atoms where the influence of orbital relaxations is significant but cross sections slightly depend on the relativistic effects..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1202001 (2016)
Photodetachment of H- in a Rectangular Cavity
TANG Tian-tian, ZHU Zi-liang, and YAO Jian-gang
On the basis of the semi-classical closed orbit theory, the effect of rectangular cavity on electron photo-detachment from a hydrogen negative ion was studied. Using the law of reflection, the electrons motion of closed orbit associated with photo-detachment cross section in the rectangular cavity was analyzed, and theOn the basis of the semi-classical closed orbit theory, the effect of rectangular cavity on electron photo-detachment from a hydrogen negative ion was studied. Using the law of reflection, the electrons motion of closed orbit associated with photo-detachment cross section in the rectangular cavity was analyzed, and the formula of photo-detachment cross section in the system was deduced. Under the action of linear polarization light, the influence of the size of the cavity on cross section was studied, and the results were compared with that of the quantum mechanics method which MA Zhi-Jun used. It is shown that, the existence and the size of rectangular cavity induces significant oscillation in the photo-detachment cross section owing to the interference effects of the electron wave traveling along closed orbits and source function. The oscillatory structure in the photo-detachment cross section sensitively depends on the size of rectangular cavity. When the laser is linearly polarized in the x-axis or y-axis, quantum mechanics results are in line with the classical results. But when the laser is linearly polarized in the z-axis, rectangular cavity is not function on cross section along z-axis in actual situation, cross section is with the case of no field by semi-classical method, while the volatility is still exist in cross section by quantum mechanics method, which shows that the semi-classical method results are more accurate in this system. The results will be useful in understanding the photo-detachment of negative ions or electron transport in a micro-cavity..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1202002 (2016)
Arrival Angle Fluctuations of Partially Coherent Beams in the Atmospheric Turbulence
KE Xi-zheng, and XUE Yao
Arrival angle fluctuations of partially coherent beams have been studied in the atmospheric turbulence. Using the model of modified Von Karmon spectrum considering its inner-scale and outer-scale, generalized huygens-fresnel principle and cross-spectrum density function, the expressions of arrival angle fluctuations ofArrival angle fluctuations of partially coherent beams have been studied in the atmospheric turbulence. Using the model of modified Von Karmon spectrum considering its inner-scale and outer-scale, generalized huygens-fresnel principle and cross-spectrum density function, the expressions of arrival angle fluctuations of partially coherent beams have been deduced in the atmospheric turbulence. The influence to arrival angle fluctuations of partially coherent beam, on the turbulence along a horizontal path have been analyzed in different turbulence scales, different turbulence intensity, different transmission distance, different source coherence parameters and different wavelength. The result shows that with the increase of transmission distance, arrival angle fluctuation is more and more small; with the increase of atmospheric turbulence scale and source coherent parameters, arrival angle fluctuation is bigger and bigger; compared with the partially coherent beam, the influence of the arrival angle fluctuation of the completely coherent beams turbulence is very small; with the decrease of the wavelength and intensity of turbulence, arrival angle fluctuation is more and more small..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1206001 (2016)
Ultra Wideband Tunable Microwave Photonic Filter Based on HB-PCF and Fiber Ring
CAO Ye, YANG Jing-peng, TONG Zheng-rong, and XU Dong
An ultra wideband tunable microwave photonic filter based on high birefringence photonic crystal fiber and fiber ring was proposed. The multi-wavelength fiber laser was used as the light source, and the high birefringence photonic crystal fiber was filled with temperature-sensitive liquid. The high birefringence photonAn ultra wideband tunable microwave photonic filter based on high birefringence photonic crystal fiber and fiber ring was proposed. The multi-wavelength fiber laser was used as the light source, and the high birefringence photonic crystal fiber was filled with temperature-sensitive liquid. The high birefringence photonic crystal fiber could own different birefringence by varying the temperature of temperature-sensitive liquid, and the laser output with different wavelengths was obtained, making the microwave photonic filter have different free spectral range. The simulating results show that when the temperature is changing from 20℃ to 80℃, the free spectral range of filter has the range of 2.49 GHz to 39.9 GHz. By introducing the fiber ring cascade in the microwave photonic filter, the main sidelobe suppression ratio of the filter can be raised to 33.6dB and the maximum Q-value of 499 can be obtained, which improve its frequency selectivity effectively..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1206002 (2016)
Analysis on the FBG Distributed Non-uniform Strain Reconstruction Precision
SHEN Xiao-yan, HAN Ya, ZHANG Liang-yue, LI Dong-sheng, and SUN Zhi-peng
Based on the LP (Layer Peeling) algorithm, the important influence factors on the reconstruction precision of the Fiber Bragg Gratings non-uniform strain, including the demodulation range of FBG non-uniform strain, the characteristic parameters of LP algorithm and the Fiber Bragg Gratings structure parameters, were numBased on the LP (Layer Peeling) algorithm, the important influence factors on the reconstruction precision of the Fiber Bragg Gratings non-uniform strain, including the demodulation range of FBG non-uniform strain, the characteristic parameters of LP algorithm and the Fiber Bragg Gratings structure parameters, were numerically analyzed. From lots of simulating experiments, the results show, that the best proper strain demodulation is less than 3 000 με of Fiber Bragg Gratings with normal working length of 5~30 mm, and keeping the fractional length of nearby 0.1 mm for LP reconstruction algorithm can obtain the best precision of strain reconstruction. Remaining above conditions, it is found that the non-uniform strain reconstruction error is smaller when the refractive index modulation decreases, and for the strong grating, the refractive index modulation amplitude of approximate 0.000 12 is the best choice in Fiber Bragg Gratings non-uniform strain sensing. The results obtained here have certain guiding significance for improving the accuracy of Fiber Bragg Gratings non-uniform strain reconstruction..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1206003 (2016)
Simultaneous Measurement of Dual-parameter Based on Optical Fiber Magnetic Field Sensor
ZHAO Yue, CAO Ye, TONG Zheng-rong, and WANG Yan
An optical fiber magnetic field sensor was proposed and demonstrated. The sensor head is composed of a Mach-Zehnder Interferometer (MZI) cascading with a Fiber Bragg grating (FBG). The MZI consists of a taper structure and a peanut-shape structure, which are encapsulated in capillary with Magnetic Fluid (MF) . The tapeAn optical fiber magnetic field sensor was proposed and demonstrated. The sensor head is composed of a Mach-Zehnder Interferometer (MZI) cascading with a Fiber Bragg grating (FBG). The MZI consists of a taper structure and a peanut-shape structure, which are encapsulated in capillary with Magnetic Fluid (MF) . The taper structure and peanut-shape structure is equivalent to an optical splitter and a coupler respectively. The external magnetic field intensity can be measured by the variation of characteristic wavelength as the effective refractive index of MF changes with the variation of magnetic field intensity. The transmission peak of FBG is insensitive to magnetic field intensity, the experimental results show that, when the magnetic field intensity varies from 0mT to 20 mT, the magnetic field sensitivity is 0.11 nm/mT. Experimental results show that, the temperature sensitivities of the interference peak of MZI and the transmission peak of FBG are 0.401 5 nm/℃ and 0.011 4 nm/℃, respectively. Therefore, the simultaneous measurement of the magnetic field intensity and temperature is demonstrated based on the sensitive matrix..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1206004 (2016)
Doppler Frequency Estimation of Coherent Doppler Wind Lidar Based on Periodogram Maximum Likelihood Algorithm
HU Yi-hua, YU Lei, XU Shi-long, LI Le, and DONG Xiao
Using the estimation uncertainty of the radial velocity and the detection probability as the evaluation index, the Doppler frequency estimation performance of Periodogram Maximum Likelihood (PML) algorithm was studied. Based on the stratified atmosphere laser echo model, the echo signal was processed by PML and PeriodoUsing the estimation uncertainty of the radial velocity and the detection probability as the evaluation index, the Doppler frequency estimation performance of Periodogram Maximum Likelihood (PML) algorithm was studied. Based on the stratified atmosphere laser echo model, the echo signal was processed by PML and Periodogram Maximum method (PM) respectively to verify the feasibility of PML algorithm. The uncertainties of estimated wind speed and detection probability were analyzed comparatively under the different signal-to-noise ratios condition with PML algorithm. The simulation results show that, with a transmitting pulse width of 400ns and the sampling points of 128, the PML algorithm is suitable for moderate signal-to-noise ratio, and the overall uncertainty of the estimated wind speed is lesser than PM algorithm. When the signal-to-noise ratio is -13 dB, the radial velocity estimation uncertainty is 0.75 m/s and detection probability is more than 90%. This study provides guidance for subsequent field trials..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1207001 (2016)
Simulation of Underwater Laser Fuze Echo Based on Bidirectional Reflectance Distribution Function
TAN Ya-yun, ZHANG He, and ZHA Bing-ting
Aiming at the necessity of torpedo laser proximity fuze detecting underwater near field target, study on Monte Carlo simulation of underwater laser fuze echo was carried out. The Monte Carlo simulation model of underwater target echo was developed based on the characteristics of underwater laser fuze detection. In ordeAiming at the necessity of torpedo laser proximity fuze detecting underwater near field target, study on Monte Carlo simulation of underwater laser fuze echo was carried out. The Monte Carlo simulation model of underwater target echo was developed based on the characteristics of underwater laser fuze detection. In order to improve the echo simulation accuracy of the underwater non-Lambertian target, The probability distribution of photon reflecting direction based on bidirectional reflectance function was derived. Then the direction of photon reflection was randomly sampled according to the probability distribution. The underwater target echo under the condition of different distances and the incident angle was simulated. The results show that target echo amplitude decreases rapidly with the increase of target distance and incident angle. The dynamic range of signal peak achieves 11.5 dB when target distance changes within 6~12 m; the dynamic range of signal peak achieves 9.2 dB when target distance is 8 m and incident angle changes within 0~45°. The experiment of underwater target laser detection was conducted in a water tank to verify the correctness of the simulation method. The experimental data have a good consistency with the simulation results. It improves the effectiveness of traditional Monte Carlo method in non-Lambertian underwater target echo simulation which provides a theoretical reference for underwater laser fuze design..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1207002 (2016)
Demodulation Error of Fringe Counting Method for Optical Fiber Fabry-Perot Sensor
XU Heng-yi, LEI Xiao-hua, CHEN Wei-min, and CHEN Tao
To investigate the demodulation accuracy of fringe counting method for optical fiber Fabry-Perot sensor, the cavity length demodulation error of the fringe counting method based on the composite algorism of crest and trough, and its influence factors that may cause demodulation errors were studied theoretically and expTo investigate the demodulation accuracy of fringe counting method for optical fiber Fabry-Perot sensor, the cavity length demodulation error of the fringe counting method based on the composite algorism of crest and trough, and its influence factors that may cause demodulation errors were studied theoretically and experimentally. Results show that, the main influencing factors are interference ordersand location errors of spectral peaks and valleys. The variations of interference orders with the cavity length will cause periodic jitter demodulation errors, and the period equals a quarter of the center wavelength of light souce. Location errors of spectral peaks and valleys determine the magnitudeof demodulation errors, that is, the larger the location errors are, the larger the demodulation errors will be..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1207003 (2016)
Improved Phase Generated Carrier Modulation and Demodulation Method
LANG Jin-peng, CHANG Tian-ying, CHEN Jian-dong, LIU Ye, CUI Hong-liang, and YU Miao
Based on detailed analysis of modulation methods, frequency mixing principle, modulation depth value and so on, in order to get a better ability of anti-interference, combining the phase generated carrier demodulation and modulation technology with the differential and cross multiplying demodulation algorithm, introducBased on detailed analysis of modulation methods, frequency mixing principle, modulation depth value and so on, in order to get a better ability of anti-interference, combining the phase generated carrier demodulation and modulation technology with the differential and cross multiplying demodulation algorithm, introducing the method of division operation, an improved phase generated carrier demodulation method was proposed in this paper to reduce the effect of light intensity disturbance. Meanwhile, its demodulation results were compared with that of the traditional method and a simulation experiment was carried out. The demodulation results when the frequency of signal source is 20 Hz and 200 Hz were compared, the results indicate that in the condition of light intensity has a 1 Hz low frequency disturbance, the improved demodulation algorithm is much better than the traditional algorithm, especially in linearity and capacity of resisting low frequency disturbance for high frequency demodulation..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1207004 (2016)
Fast Blind Image Restoration Algorithm Based on Power Law
GAO Wei-zhe, ZOU Jian-hua, ZHANG Rong-zhi, and WANG Jia-song
Aiming at the problems that the existing iterative blind image restoration algorithms are mostly time-consuming and their convergence guaranteeing is difficult, a fast algorithm was proposed. Firstly, the spectrum of original image is reconstructed in accordance with the power law. Then, utilizing the relationship betwAiming at the problems that the existing iterative blind image restoration algorithms are mostly time-consuming and their convergence guaranteeing is difficult, a fast algorithm was proposed. Firstly, the spectrum of original image is reconstructed in accordance with the power law. Then, utilizing the relationship between the spectrums of the orignal and reconstructed images, the Point Spread Function (PSF) is estimated by the multidirectional comprehensive estimation, which can reduce the estimation error and enhance the stablility. Finnaly, the restored image is obtained by using the estimated PSF and Wiener filter. The proposed algorithm was compared with the existing algorithms by experiments. The results show that for the class G PSFs which fit for the numerous imaging systems, the proposed algorithm can obtain more accurate PSF, and reduce the ringing artifacts, yielding restored images with higher quality..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1210001 (2016)
Adaptive Image Enhancement Based on Multiple Algorithm Fusion
JU Gang, YUAN Liang, LIU Xiao-yue, and HE Wei
For the detail features of the complex degraded images being effectively restored in engineering application, an image enhancement method of the multiple algorithm-fusion was introduced. This fusion algorithm is based on the theory of digital image and integrates the advantages of the Laplace transform, Sobel gradient,For the detail features of the complex degraded images being effectively restored in engineering application, an image enhancement method of the multiple algorithm-fusion was introduced. This fusion algorithm is based on the theory of digital image and integrates the advantages of the Laplace transform, Sobel gradient, box filtering, unsharp masking filter method and gray exponential law strength into the algorithm to enhance the fuzzy images adaptively. The original image, firstly, is decomposed into a base layer, a detail layer and a edge character layer by the Laplace filter and gradient filter. Secondly, the tiny details and edge characteristic information are enhanced and base information is compressed. Then the three layers of the image are processed smoothly and the noise is filtered by the box filtering. Finally, the dynamic range of gray level image is increased by the gray-scale transformation and the unsharp masking method, and the enhanced image is obtained. And under the same load conditons, the proposed method is compared respectively with the traditional algorithms of the HE, AGCWD and WT. The experiment results show that this method can effectively handle the complex images with infection, and the sharpness of the image is increased by 13.1% ~ 126.1%, and avoid the phenomenon of excessive image enhancement, and obtain a superior subjective visual detail effects..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1210002 (2016)
Study on Adaptive Exposure Time for Low-light Staring Imaging
WANG Ya-min, YANG Xiu-bin, JIN Guang, XU Wei, and ZHANG Zhao
In order to realize the long period gaze exposure imaging for low-light application, an exposure period algorithm was designed to match the attitude change of gaze tracking image. Based on the mathematical model of the satellite to ground real-time gaze tracking, the velocity matching exposure imaging relations was setIn order to realize the long period gaze exposure imaging for low-light application, an exposure period algorithm was designed to match the attitude change of gaze tracking image. Based on the mathematical model of the satellite to ground real-time gaze tracking, the velocity matching exposure imaging relations was set up. Image motion was induced by three-axis attitude angle and control accuracy of attitude angular velocity during the low-light imaging exposure period produces, and it can be calculated by using the method of the Monte Carlo. And exposure period was analyzed to meet the satellite attitude control accuracy in the low-light imaging. Finally, an on-orbit test of adaptive exposure period of low-light imaging algorithm was carried out on the smart verification satellite. Results show that: the corresponding imaging exposure time is18 ms and 55.2 ms respectively when the control accuracy of satellite attitude is 0.08°,0.0088°/s and 0.04°,0.003°/s . The actual deviation pixel of target point in the process exposure at imaging is less than 1 pixel. This bias has little influence on the imaging quality and image signal-to-noise ratio..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1211001 (2016)
High Accuracy Measurement of the MTF of Electro-optical Imaging System Based on Modified Slanted-edge Method
LI Hang, YAN Chang-xiang, SHAO Jian-bing, and WANG Xiao-peng
In this study, an improved slanted edge method was proposed. It had a high accuracy for measuring the Modulation Transfer Function (MTF) of electro-optical imaging system. We put forward an automatic determination of the high and low threshold modified Canny operator to detect the edge points, and the edge slant angle In this study, an improved slanted edge method was proposed. It had a high accuracy for measuring the Modulation Transfer Function (MTF) of electro-optical imaging system. We put forward an automatic determination of the high and low threshold modified Canny operator to detect the edge points, and the edge slant angle is obtained by linear fitting of the edge points. In the process of fitting the edge spread function (ESF) by Fermi function, we put forward a modified method to reduce the influence of noise. It was composed of averaging in adjacent region and setting the tolerance of error. The method in this paper is proved effectively by the experimental results, and analyzing the influence of the change of the edge slant angle and noise on the MTF measurement accuracy. The experimental results show that the measurement accuracy of the modified slanted edge method is 0.004 9, and the repeat accuracy is 0.003 1, which is higher than the traditional methods. It proves that the modified slanted edge method has high measurement and repeat accuracy, and also has a better immunity to noise and edge angle..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1211002 (2016)
Application of Chalcogenide Glass in Designing a Long Wavelength Infrared Athermalized Wide-angle Lens
WANG Jing, WU Yue-hao, JIANG Bo, DAI Shi-xun, XU Tie-feng, and MU Rui
A Long Wavelength Infrared(LWIR) wide-angle lens whose Field Of View(FOV) is 110° was proposed. The operating wavelength of the lens is a range from 8 to 12 μm, the operating temperature range is -40℃~60℃, the effective focal length is 5mm, and the F number is 2. This design utilizes a combination of 6 lens elemenA Long Wavelength Infrared(LWIR) wide-angle lens whose Field Of View(FOV) is 110° was proposed. The operating wavelength of the lens is a range from 8 to 12 μm, the operating temperature range is -40℃~60℃, the effective focal length is 5mm, and the F number is 2. This design utilizes a combination of 6 lens elements that are made of chalcogenide glass materials, Zinc Sulfide, and Zinc Selenide. The optical powers of the lens elements as well as their locations were carefully calculated and optimized to simultaneously eliminate the chromatic and thermal aberrations for the designed wavelength/temperature range. Taking advantage of the superior molding capability of chalcogenide glasses, the proposed design incorporates three aspherical surfaces on lens elements fabricated with chalcogenide glasses, such that optical aberrations can be furtherly corrected. According to the design results, the proposed system can produce thermal images with a close to diffraction limited performance for the temperature range from -40℃ to 60℃. At the spatial frequency of 15 lp/mm, the Modulation Transfer Function(MTF) values of the proposed system are higher than 0.4 for the entire FOV, and at the same time, system distortion is controlled below 5%..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1211003 (2016)
Catadioptric Null Compensating Test(Continued)
ZHANG Long, HU Wen-qi, ZHENG Lie-hua, and HAO Pei-ming
In order to study the effct of different spherical aberration distribution between the double lens and single mirror on the compensation results of catadioptric compensator, based on the third-order aberration theory, aiming at two concave paraboloidal surfaces with different relative apertures, a set of catadioptirc cIn order to study the effct of different spherical aberration distribution between the double lens and single mirror on the compensation results of catadioptric compensator, based on the third-order aberration theory, aiming at two concave paraboloidal surfaces with different relative apertures, a set of catadioptirc compensators with different spherical aberration assignment were designed, and the curves of the design results were drawn. The curves indicate that,when the spherical aberration bearing ratios of the single mirror increase from 0 to 0.5, the compensating ability of the catadioptric compensators rises fist, and begins to decrease after reaching the maximum.When the spherical aberration bearing ratio of the single mirror is 0, it means that the single mirror will not help to the final compensation and the single mirror becomes a plane reflector, and the catadioptric compensator becomes an Offner compensator. The results show that, the compensating ability of catadioptric compensator is strong, the different distribution of spherical aberration bearing ratios has a great impact on the compensating results, and it is good to the catadioptric compensator design to choose a reasonable spherical aberration bearing ratio for the single mirror..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1222001 (2016)
Design of High-precision Static Star Simulator with Uniform Sky Background
LIU Shi, ZHANG Guo-yu, SUN Gao-fei, WANG Ling-yun, and GAO Yu-jun
To solve the problem that the existing star simulators are only concerned with the precision of star map simulation while neglects the sky background simulation, a high-precision static star simulator was designed under a uniform background of sky. In this paper, the components and operating principles of the star simuTo solve the problem that the existing star simulators are only concerned with the precision of star map simulation while neglects the sky background simulation, a high-precision static star simulator was designed under a uniform background of sky. In this paper, the components and operating principles of the star simulator were elaborated emphatically, and the optimal design method was also discussed in detail for the optical system. According to simulator's optical system which was featured with big lens and high precisions, the lens cone was designed to have a fixed, tube-in-tube structure. Moreover, in order to guarantee the precision of star map simulation, the laser direct writing technology was adopted to fabricate star testers with a precision exceeding ±1 μm. Test results indicated that the star map simulation precision of the designed high-precision static star simulator with a uniform sky background is greater than 3″and the sky background uniformity is larger than 95%. Therefore, it is able to satisfy requirements of high-precision ground calibration and functional test for navigation sensors..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1222002 (2016)
Polarization Interference Method for Dynamic Measurement of Twisted Nematic Liquid Crystal Director
MA Jing, PEI Li-yan, XU Can-hua, and ZHOU Xiong-tu
A real-time method for measuring the polarization state based on birefringence crystal wedge was proposed and it was applied to analyze the polarization state of transmitted light from twist nematic liquid crystal, the dynamic measurement of liquid crystal molecule mean director was achieved by this method. PolarizatioA real-time method for measuring the polarization state based on birefringence crystal wedge was proposed and it was applied to analyze the polarization state of transmitted light from twist nematic liquid crystal, the dynamic measurement of liquid crystal molecule mean director was achieved by this method. Polarization interference method based on crystal wedge was used to encode the polarization parameters of detected light into two groups of interference fringes, real-time measurement of polarization state was realized through stripe position location. According to the relationship between the director angle of liquid crystal director and transmitted polarization state, dynamic information of liquid crystal mean director can be derived. The measurement speed is 5 time per second in this experiment, and the accuracy of tilt and twist angle of liquid crystal average director is 0.2 degree. An effective and valuable approach for rapid measurement of liquid crystal molecule mean director is provided in this work..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1226001 (2016)
High-order Bessel Beam Focused by Cylindrical Lens Generated Caustic Optical Beam
FENG Cong, WU Feng-tie, and XIE Xiao-xia
The distribution characteristics of optical field of high-order Bessel beam after pasing through the cylindrical lens were studied. Based on the generalized Huygens Fresnel diffraction integral theory, the expression of the diffractive light intensity distribution of which the high-order Bessel beam passing through cylThe distribution characteristics of optical field of high-order Bessel beam after pasing through the cylindrical lens were studied. Based on the generalized Huygens Fresnel diffraction integral theory, the expression of the diffractive light intensity distribution of which the high-order Bessel beam passing through cylindrical lens was derived. And the intensity distribution in different propagative distances was numericaly simulated by MATLAB and MATHCAD. In the experiment, the high-order Bessel beam was generated by axicon lens and spiral phase plate, and passed through the cylindrical lens. The optical intensity distribution in different propagation distances was captured by a CCD camera. The study results show that, a high-order Bessel beam through the cylindrical lens can form a lip-shaped caustic optical beam..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1226002 (2016)
Mechanism of Three-dimension Sensing with Fiber Gratings for Structure Cracks Detection
WANG Li-li, XIN Xiang-jun, and HAO Jin-guang
A method using for the detection and analysis of the three-dimension strain sensing signals of the longitudinal concrete cracks was proposed by utilizing the reflectance spectrum of fiber gratings. The fracture model of three-dimension finite element using bottom-up method based on ANSYS was given. The three-axis stresA method using for the detection and analysis of the three-dimension strain sensing signals of the longitudinal concrete cracks was proposed by utilizing the reflectance spectrum of fiber gratings. The fracture model of three-dimension finite element using bottom-up method based on ANSYS was given. The three-axis stress applied on the fiber grating under uniform and radial force was presented, the three-axis strain function was derived on the basis of above-mentioned stress field, and the relation curve between resonance wavelength of x-polarization, y-polarization and three-axis stress was given. The variation of reflective spectrum of fiber grating of 10 cm length is calculated using transfer matrix method under three-axis strain based on theoretical analysis and numerical calculation, the results show that, the peak wavelength shifts of x-polarization and y-polarization are 10.1 nm and 12 nm respectively under uniform and radial force of 20N. At the same time,the reflection spectra of the fiber Bragg grating split into two main peaks and the spectral difference of the two peaks increases linearly,and the split point shiftes to long-wavelength, the reflectivity of shorter wavelength is higher than the long-wavelength but the bandwidth of shorter wavelength is less than the long-wavelength when the load increases. The (Full Width Half Maximum, FWHM) of the two splitted reflection peaks increases but the spectral peaks space remains unchanged almost when the length of grating increases to 15 cm under same force compared to grating of 10 cm length.The sensitivity of the grating proposed in the paper is up to 0.14 nm/N.The two-dimension sensing is extended to three-dimension sensing based on single grating with the method proposed in this paper..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1228001 (2016)
Self-referenced SPR Sensor Based on Au/ITO Nanocomposite
LI Zhi-quan, HE Jia-huan, WANG Ya-juan, FENG Dan-dan, GU Er-dan, and LI Wen-chao
A self-referenced dual mode surface plasmon resonance sensor based on Au/ITO nanocomposite material was designed. The proposed sensor can generate two resonance peaks namely resonance peak 1 and resonance peak 2. The results reveal that the resonance peak 1 has larger drifts with the changing of the refractive index ofA self-referenced dual mode surface plasmon resonance sensor based on Au/ITO nanocomposite material was designed. The proposed sensor can generate two resonance peaks namely resonance peak 1 and resonance peak 2. The results reveal that the resonance peak 1 has larger drifts with the changing of the refractive index of measured medium and the incident angle, but the resonance peak 2 drifts only with the change of incident angle. Two peaks are cross-referenced, and the influence of the incident angle shift on the measurement results is reduced, which improves the accuracy of the measurement results. We investigate the effect of the incident angle, refractive index of sensing medium and thickness of the thin film on two peak of wavelength with different volume fraction of nanocomposite materials. When the incident angle θ is 80°, the volume fraction of Au f is 0.65, film thickness d is 40nm and d is 45nm, and the volume fraction of Au f is 0.85, film thickness d is 45 nm and 50 nm, the resonance peak 2 does not vary with the change of the refractive index,only the resonance peak 1 varies with the change of the refractive index to achieve the desired state of self-referenced sensor..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1228002 (2016)
Fiber-optic Fabry-Perot High-temperature Sensor Based on Sapphire Wafer
LIANG Wei-long, ZHOU Ci-ming, FAN Dian, OU Yi-wen, TIAN Tao, GUI Xin-wang, and LI Yan
A fiber-optic Fabry-Perot (F-P) high-temperature sensor based on sapphire wafer was proposed and fabricated. The sensor uses the sapphire fiber with angled end face as a transmission waveguide, the sapphire wafer as a Fabry-Perot (F-P) interferometer and the structure of “Zirconia ferrule-Zirconia tube”as the fixing stA fiber-optic Fabry-Perot (F-P) high-temperature sensor based on sapphire wafer was proposed and fabricated. The sensor uses the sapphire fiber with angled end face as a transmission waveguide, the sapphire wafer as a Fabry-Perot (F-P) interferometer and the structure of “Zirconia ferrule-Zirconia tube”as the fixing structure of the sensor. The reflection spectrum of the interferometer was demodulated by performing a combined algorithm of fast Fourier transform algorithm and minimum mean square error estimation.Temperature ranged from 20℃ to 1000℃ is measured, and the obtained precision is ±2.5℃. The sensor has the advantages of small size, low cost, simple fabrication and high repeatability. It can be applied for stable and accurate temperature measurement in high temperature environments..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1228003 (2016)
Design of a Sensing Coil in Portable Fiber Optic Current Transformer
WANG Xia-xiao, ZHANG Yu-ning, YU Jia, and LI Chuan-sheng
To deal with the problem of complex large current measurement site in electrolytic aluminum industry, a portable fiberoptic current transformer was proposed on the basis of the traditional fiber opticcurrent transformerin. The Faraday phase shift error which caused by the flexible sensing coil non-closed optical path aTo deal with the problem of complex large current measurement site in electrolytic aluminum industry, a portable fiberoptic current transformer was proposed on the basis of the traditional fiber opticcurrent transformerin. The Faraday phase shift error which caused by the flexible sensing coil non-closed optical path and current conductor eccentric position in the process of design and installation was analyzed and calculated by finite element method. It has been obtained that the Faraday phase shift relative error increases linearly with the non-closed angle of sensing coil and decreases with the increasing distance between conductor and the non-closed point, and the Faraday phase shift relative error can be decreased by increasing number of turns. Based the accuracy of portable fiberoptic current transformer increases with the distance between conductor and the non-closed point, a sensor head structure with the extending non-closed point and easy accessibility was designed, it has been obtained that the full temperature accuracy is 0.86% of portable fiberoptic current transformer by experimental test, which meets the required accuracy 1% in smelter..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1228004 (2016)
Development of Outdoor Lighting Lampshade Self-cleaning Composite Film
FU Xiu-hua, FAN Jia-chen, ZHANG Jing, XIONG Shi-fu, and ZHANG Yu-shuai
According to the environmental requirements of self-cleaning quality for outdoor lighting system, the refractive index of composite film and the quality ratios were analyzed and simulated based on the theory of optical thin film. The method of electron beam evaporation was used to plate the Ti02/A1203 composite film, aAccording to the environmental requirements of self-cleaning quality for outdoor lighting system, the refractive index of composite film and the quality ratios were analyzed and simulated based on the theory of optical thin film. The method of electron beam evaporation was used to plate the Ti02/A1203 composite film, and then the composite film was given for the vacuum annealing treatment. By controlling the beams of the left and right of the electron gun, the different mass ratios plating composite film was prepared in the single-crystal control system. The hydrophilic test and the Methyl orange experiment shows that, the higher the quality ratio of Ti02 is, the better the self-cleaning effect is, but the ability of hydrophilic and visible light transmittance are both reduced. The composite film with different quality ratios were tested and analyzed. And the paper adjusts the mass ratio to optimize the test plan, the results show that, when the mass ratio of the Ti02/A1203 is 9∶1, the film not only has a self-cleaning hydrophilic interaction, but also with a high visible light transmittance..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 45, Issue 12, 1231001 (2016)
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