Journals >Acta Photonica Sinica
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2012
Volume: 41 Issue 5
24 Article(s)
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Research Article
Optical Measurement of Ф750 mm Telescope System
MING Ming, YANG Fei, WANG Fuguo, and L Tianyu
For detecting space debris in the high orbit, a telescope with wide field of view (4°), large relative aperture (1∶1.32) and broad wavelength (500 nm to 800 nm) is obtained. The telescope, whose clear aperture is Ф750 mm, consists of primary mirror and refractive corrector group. The surface type of primary mirrorFor detecting space debris in the high orbit, a telescope with wide field of view (4°), large relative aperture (1∶1.32) and broad wavelength (500 nm to 800 nm) is obtained. The telescope, whose clear aperture is Ф750 mm, consists of primary mirror and refractive corrector group. The surface type of primary mirror is parabolic, and the refractive corrector group includes one ellipsoid lens and three spherical lenses. The advanced methods of optical elements measurement and whole system are introduced respectively. Firstly, the figure error of spherical lens is measured using template method. A compensation test method of null lens is used to test the hyperbolic primary mirror and ellipsoid corrector lens. Next, when the corrector lens group is aligned, the whole corrector lens group is tested making use of a new spherical mirror method. And at last, it is adopted to measure the optical telescope with collimator test in the room and with nature star observation outdoors. All of the measurement results are satisfying the requirement of design. The figure errors of spherical lenses are less than 0.1 fringe in the first step, the figure errors of primary mirror and ellipsoid lens are less than λ/30 (RMS), and the wavefront error at the third step is less than λ/30 (RMS). After measuring the whole telescope optical system in the room, the 80% encircled energy is within 2 pixels, at the side of that, when observing the stars outdoors, the 80% encircled energy is also within 2 pixels in the whole field of view, 4° diagonal..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 505 (2012)
Flatten Calibration of Deformable Mirror Based on the Measurement of the Interferometer
LIN Xudong, LIU Xinyue, WANG Jianli, WEI Peifeng, and WANG Fuguo
In order to make the adaptive optical system function well, it needs to have a full understanding of the performance of the deformable mirror, so a technique for the flatten calibration of the deformable mirror based on the measurement of the interferometer is presented. Firstly, all the PZT actuators are set to the miIn order to make the adaptive optical system function well, it needs to have a full understanding of the performance of the deformable mirror, so a technique for the flatten calibration of the deformable mirror based on the measurement of the interferometer is presented. Firstly, all the PZT actuators are set to the midrange of their control voltage; and then, the height of the mirror surface with the ZYGO interferometer is measured, the height of mirror surface at each actuator is calculated, and the differences between the height of the mirror surface at each actuator and the average height of the mirror surface are figured out; finally, the actuators are controlled to reduce the differences to zero. The results show that affected by the hysteresis of the PZT actuator, the mirror surface needs 4 to 6 iterative processes showed above to reach the same preset desired flatness; for the 21elements deformable mirror, which without the actuators under the periphery of the mirror, an rms surface figure near λ/20（λ=632.8 nm） at its 80% aperture is achieved; for the 137elements deformable mirror, which has actuators under the periphery, the rms surface figure is better than λ/50. Under different observation conditions of the telescope, this technique can flat the deformable mirror rapidly in the adaptive optical system, in order to adapt to changing working conditions..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 511 (2012)
Dispersion Properties of Ge20Sb15Se65 Chalcogenide Glass Photonic Crystal Fiber for MidIR Region
LIU Yongxing, ZHANG Peiqing, XU Yinsheng, DAI Shixun, WANG Xunsi, XU Tiefeng, and Nie Qiuhua
Compared with silica glass, chalcogenide glass possesses some unique advantages, such as high refractive index (2.0～3.5), low phonon energy (lower than 350 cm－1), and large infrared transmission window (up to 25 μm). In this paper, a kind of environmental protected Ge20Sb15Se65 chalcogenide glass was prepared, which shCompared with silica glass, chalcogenide glass possesses some unique advantages, such as high refractive index (2.0～3.5), low phonon energy (lower than 350 cm－1), and large infrared transmission window (up to 25 μm). In this paper, a kind of environmental protected Ge20Sb15Se65 chalcogenide glass was prepared, which showed good transmission in IR range. Based on this glass, a photonic crystal fiber with three rings air holes was designed. Multipole method was employed to study the dispersion properties of the designed photonic crystal fiber. The relationship between fiber structure parameters（the air diameter d, period Λ and the ratio d/Λ）and dispersion properties was presented. The simulation results showed that the zero dispersion point of photonic crystal fiber can be flexibility tuned to short or long wavelength region by control the fiber structure parameters. Finally, by optimizing the sturcure parameters, the dispersion flat photonic crystal fiber through of 3~5 μm was obtained, with the dispersion value less than 5 ps·nm－1·km－1..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 516 (2012)
Transmission Performance of Ultra Wideband Pulse Radar Signal over Fiber
YAO Xianxun, and YAN Juanjuan
Monocycle pulse and doublet pulse used for ultrawideband (UWB) pulse radar are generated with dualparallel MachZehnder modulator (DPMZM). Based on the fadio over fiber (RoF) technology, the transmission performance of the UWB pluses over standard single mode fiber (SSMF) are theoretically analyzed. It is found that Monocycle pulse and doublet pulse used for ultrawideband (UWB) pulse radar are generated with dualparallel MachZehnder modulator (DPMZM). Based on the fadio over fiber (RoF) technology, the transmission performance of the UWB pluses over standard single mode fiber (SSMF) are theoretically analyzed. It is found that monocycle pulse is broadened with the increase of transmission distance, while doublet pulse is firstly compressed and then broadened. Monocycle pulse and doublet pulse with different width satisfying the FCC requirements of UWB pulse radar can be obtained, when the accumulated dispersion of the radar signal is compensated in different degree with dispersion compensation fiber (DCF) after 100 km transmission over SSMF..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 522 (2012)
Evaluation of Shrinkage Stress and Exotherm during Lightcuring of Dental Resin Composites
LIU Lin, YE Zhiqing, RAO Chunfang, HU Youde, KUANG Fan, and WANG Yan
Lightcured composite resin is an important material in densitry for beauty and restoration. Fiber Bragg gratings(FBG) is used to determine composite resin shrinkage during the lightcuring. Because FBGs are both sensitivity to temperature and strain, two different kinds of FBGs were used to calculate the temperature aLightcured composite resin is an important material in densitry for beauty and restoration. Fiber Bragg gratings(FBG) is used to determine composite resin shrinkage during the lightcuring. Because FBGs are both sensitivity to temperature and strain, two different kinds of FBGs were used to calculate the temperature and strain respectively. One of the FBG was bare, and the other was chemical plated FBG, both of which were embedded in one sample of resin simultaneously. LED light source was used for light curing. Real time changes of temperature and shrinkage strain were gained. The experiments showed that the resin expressed strong shrinkage strain and temperature variation because of the polymerization reaction during the curing. The results are helpful for understanding the shrinkage and temperature change of the materials and improving more prefecable treatment effect..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 528 (2012)
A Model for Evaluating the Mechanical Reliability of Coiled Fibers
LIANG XiaoHong, LIU XiaoDong, and LIU JunHao
It is necessary to evaluate the mechanical reliability of the coiled fibers to evaluate the mechanical reliability of fiber coils applied in sensing fields, such as fiberoptic gyroscope and current sensors, besides the causes of fiber coatings and loop glues. A model is proposed for evaluating the mechanical reliabiliIt is necessary to evaluate the mechanical reliability of the coiled fibers to evaluate the mechanical reliability of fiber coils applied in sensing fields, such as fiberoptic gyroscope and current sensors, besides the causes of fiber coatings and loop glues. A model is proposed for evaluating the mechanical reliability of the coiled fibers, which is based on the mechanical reliability model of the hauldistance telecommunication fibers by incorporating the bendinduced stress and the coiling tension. The model can simplify the inhomogeneous bending stresses distribution with the maximum stress value and the fact that the compressed stress in the inner side of the fiber natural axis is far small than the stretch stress outside. By these and the choosing of the parameters involved in the model, the conserved results are given using this simplified model. Several numerical caculations of mechanical reliability of various fiber coils with different fiber and bending radius are carried out using this model. The results show that besides fiber own inherent factors including the fiber radius and the fatigue factor, some process parameters, such as the circling tension, the ring radius and the screening tension also have a major impact on the mechanical reliability of coiled fibers..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 532 (2012)
Measurement Method of Fiber Nonlinear Coefficient Based on Four Wave Mixing
LI Zhi, WU Baojian, WEN Feng, and AN Junge
Pump depletion was not taken into account in the fourwavemixingbased measurement technique for fiber nonlinear coefficient, which made the results inaccurate. To solve this, the elliptical equation with pump depletion and fiber loss was derived based on the theory of degenerate fourwave mixing. The nonlinear coeffiPump depletion was not taken into account in the fourwavemixingbased measurement technique for fiber nonlinear coefficient, which made the results inaccurate. To solve this, the elliptical equation with pump depletion and fiber loss was derived based on the theory of degenerate fourwave mixing. The nonlinear coefficient of the tested fiber could be obtained by setting the parameters in numerical calculation and utilizing simple mathematical method. The necessity of considering pump depletion and fiber loss was analyzed. The numerical results were consistent with the Optisystem simulation data. The improved method proposed in the can be applied to the small signal case, but also to the process of parametric saturation. This technique provided an important parameter for further designing the fiberbased 2R regenerators..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 536 (2012)
Time Evolution Properties of Intensity Correlation Function of Single Mode Laser Driven by Periodic Signal Modulating Colouredpump Noises
GUI Di, XU Dahai, and CHENG Qinghua
Using the linear approximation method, the intensity correlation function C(t) of a single mode laser system was calculated and the time evolution of C(t) was researched as well as the influence of modulation signal frequency Ω and amplitude B on C(t) was analysed in detail. In the case of the pump noise selfcorrelatiUsing the linear approximation method, the intensity correlation function C(t) of a single mode laser system was calculated and the time evolution of C(t) was researched as well as the influence of modulation signal frequency Ω and amplitude B on C(t) was analysed in detail. In the case of the pump noise selfcorrelation time τ<<1, it was found that when modulation signal frequency Ω and amplitude B increase, the time evolution of C(t) experiences monotonous descending; however, in the case of τ>>1, as modulation signal frequency Ω and amplitude B increasing, the time evolution of C(t) exhibits periodically surging with descending envelope..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 541 (2012)
A Fuzzylogicbased Theoretical Framework for Quantitative Fidelity Evaluation of Infrared Camera Simulators
ZHANG Fudi, ZHANG Jianqi, LIU Hongmei, and XU Yin
Aiming to improve the current situation of the simulator fidelity evaluation system, a new theoretical framework based on fuzzy logic and fuzzy set theory is introduced to quantitatively evaluate the simulation fidelity of infrared camera simulators. This framework is an objective and multiparameter evaluation system,Aiming to improve the current situation of the simulator fidelity evaluation system, a new theoretical framework based on fuzzy logic and fuzzy set theory is introduced to quantitatively evaluate the simulation fidelity of infrared camera simulators. This framework is an objective and multiparameter evaluation system, which is related to many fields such as fuzzy logic, curve similarity evaluation, image quality assessment, and information theory, etc. Compared with those available, a multiscale fidelity evaluation analysis, which includes performance characteristic evaluation of the total system and image quality assessment of the camera outputs, is considered more compromisingly in this evaluation system. Consequently, the new framework here has better task flexibility and it is easier to quantify and compare the fidelity results between different camera simulators with the same or similar mission requirements..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 547 (2012)
Superresolution Reconstruction of Infrared Image Based on Selfadaptive Gradient Threshold
BAI Junqi, ZHENG Jian, ZHAO Chunguang, and WANG Xianya
In the superresolution image reconstruction, the model of Hubermarkov random field is a common regularizing operator. Aiming at the unsatisfying effect of image reconstruction caused by fixed gradient threshold in the Huber function, a superresolution reconstruction algorithm is proposed based on selfadaptive gradiIn the superresolution image reconstruction, the model of Hubermarkov random field is a common regularizing operator. Aiming at the unsatisfying effect of image reconstruction caused by fixed gradient threshold in the Huber function, a superresolution reconstruction algorithm is proposed based on selfadaptive gradient threshold. The regularizing model is structured based on data item and regular item under the maximum a posteriori probability framework; the regularizing parameters are updated using the intermediate results via iterative method and can solve the selected problem of gradient threshold in the model of Hubermarkov random field. Experimental results show, the improved algorithm can select the proper regularizing parameters based on local gratitude threshold and find the optimal result, recover detailed information and eliminate noise effectively..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 554 (2012)
Numerical Analysis of SPP Maskless Interference Lithography System
DONG Qiming, and GUO Xiaowei
The use of the surface plasmon ploritons(SPPs) instead of photons as the exposure source can pattern nanoscale feature size by its near field enhancement effects. In this paper, we numerically explore the parameter spaces in prismbased SPP lithography system. The calculation principles and methods are given out. ResulThe use of the surface plasmon ploritons(SPPs) instead of photons as the exposure source can pattern nanoscale feature size by its near field enhancement effects. In this paper, we numerically explore the parameter spaces in prismbased SPP lithography system. The calculation principles and methods are given out. Results show that high refractive indices of prism, low thickness of silver film, appropriate incidence wavelength and the refractive indices of resist contribute to optimal interference image with high expore depth and contrast. When chosing 40 nm silver film at 431 nm incidence wavelength, exposure depth achieves 200 nm, and fringes period is 110 mm. The numerical results offer theoretical support for the arrangement of the experimental setup..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 558 (2012)
Comparisons and Analysis of Drilling Experiment Using Different Pulse Laser Waveforms
SU Shi, AN Zhiyong, LIANG Wei, CONG Jingbin, and FAN Fan
In order to obtain the highquality small holes and overcome the shortcomings of single pulse laser drilling, a new multipulse laser wave is introduced. Using the new manner, the hole of which the diameter is less than 1 mm, is obtained in 1mmthick steel. Depending on the basic of theoretical analysis of multipulse In order to obtain the highquality small holes and overcome the shortcomings of single pulse laser drilling, a new multipulse laser wave is introduced. Using the new manner, the hole of which the diameter is less than 1 mm, is obtained in 1mmthick steel. Depending on the basic of theoretical analysis of multipulse drilling, the multipulse drilling can reduce the generation of melt interest and plasma, and the requirement of high energy for laser drilling. And it can also obtain the higher quality of drilling than the single laser drilling. In addition, the option of pulse width and pulse spacing is important for maching quality of laser drilling. It should choose shorter laser pulse width, when machine the highquatity hole. Through the comparison and analysis of drilling results which are generated by waveforms of single pulse laser and multipulse laser, it is known that the quality of drilling results generated by waveform of threepulse laser is superior to those of single pulse laser. And it is found that the average energy of effective pulse is 350 mJ, and the optimum pulse width and the best pulse interval are both 100 μs..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 565 (2012)
Numerical Analysis of CW Laser Damage in GaAs
LI Juan, SUN Wenjun, SUN Jingnan, ZHAO Liping, LI Mengyang, and ZHI Hongwu
Based on the heat conduction theory, a twodimensional axis symmetric transient physical model was established, of which GaAs was irradiated by Gauss laser. By solving the heat conduction equations using COMSOL Multiphysics analysis software, the curve of material surface temperature and the relationship between the teBased on the heat conduction theory, a twodimensional axis symmetric transient physical model was established, of which GaAs was irradiated by Gauss laser. By solving the heat conduction equations using COMSOL Multiphysics analysis software, the curve of material surface temperature and the relationship between the temperature at the center of the light spot and material thickness were obtained, and then the relationship between threshold damage time of GaAs and the incident light power density was gained. The calculation results show that the laser induced damage is mostly decomposition damage in the areas where temperature exceeds decomposition temperature of material. The theoretical analyzing result is in accordance with the relative experimental result, so the laser irradiation effect model proves correct..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 571 (2012)
Combined Timefrequency Imaging Method of SAL Based on Adaptive Windowing
L Xuguang, HAO Shiqi, LENG Jiaofeng, and CAI Xiaochun
RangeDoppler algorithm (RDA) is a basic method in synthetic aperture imaging. In RDA, the Doppler frequency is considered as constant, but this hypothesis is not existed in synthetic aperture ladar(SAL). Based on the echo signal model of SAL, the influence of vibration error on the phase is computed and analyzed. On tRangeDoppler algorithm (RDA) is a basic method in synthetic aperture imaging. In RDA, the Doppler frequency is considered as constant, but this hypothesis is not existed in synthetic aperture ladar(SAL). Based on the echo signal model of SAL, the influence of vibration error on the phase is computed and analyzed. On the reference of the national military standard for environment, in the condition of the frequency below 500 MHz and the amplitude below 0.2 mm, the simulation results show that the influence of vibration on the azimuth resolution is severity, but which on the range resolution is trivial. The imaging algorithm based on timefrequency analysis can overcome the limit of traditional RD algorithm effectively. Compared the imaging results used WVD, PWVD and SPWVD as kernel, they cannot suffice both the imaging resolution and imaging efficiency. A combined timefrequency imaging method based on adaptive windowing is presented to modulate the window size adaptively according to the comparison of variance coefficient and variance threshold, then the counterpoise optimize of imaging resolution and imaging efficiency is achieved. The simulation results show that the imaging resolution of this algorithm is constant, but the imaging time decreases 69.87%, and it can used in SAL for its high imaging resolution and imaging efficiency..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 575 (2012)
Handover Strategy and Simulation of Entanglement Signaling in Quantum Mobile Communication
LIAN Tao, NIE Min, and LIU Xiaohui
Quantum mobile communication with superiority of flexibility, high efficiency, security and confidentiality is a kind of new communication technology connected quantum mechanics and mobile communication. A kind of entanglement signaling handover strategy among different sector antennas in the same cell is put forward bQuantum mobile communication with superiority of flexibility, high efficiency, security and confidentiality is a kind of new communication technology connected quantum mechanics and mobile communication. A kind of entanglement signaling handover strategy among different sector antennas in the same cell is put forward based on the entanglement degree calculation. The relationships between quantum mobile communication terminal and sector antenna with variable distance and angle respectively are studied, and the entanglement signaling the handover strategy is simulated and analyzed. The simulation results show that the proposed handover strategy has high reliability, which has a great technology supporting function for the future quantum mobile communication system and its standard formulation..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 581 (2012)
Parametric Relative Properties of Thirdorder Nonlinear Optical Susceptibilities in a Zns/CdSe/ZnS CoreShellShell Spherical Quantum Dot
ZHU Dequan, and CHEN Zhihong
Under the effectivemass approximation,the analytic expression for Selffocusing effect in ZnS/CdSe/ZnS coreshellshell spherical quantum dots was derived by using the density matrix method. The numerical caculations were perforomed on the thirdorder susceptibilities as a function of the size of quantum dots and the Under the effectivemass approximation,the analytic expression for Selffocusing effect in ZnS/CdSe/ZnS coreshellshell spherical quantum dots was derived by using the density matrix method. The numerical caculations were perforomed on the thirdorder susceptibilities as a function of the size of quantum dots and the frequency of the incident light were analyzed.The numerical results reveal that the thirdorder susceptibilities will increase with the increase of the quantum dot size, and position of the peak will red shifts. The conclusions provide a theoretical basis for experimental research and practical applications, and for research and improvement of photoelectric device with references..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 586 (2012)
Reflection Holography for Threedimensional Display Based on Computergenerated Holography
BAI Xiaohui, WAN Lin, REN Yaping, HUANG Yanfang, and WANG Hui
Both of the computergenerated holograms and optical holograms can be applied to a threedimensional display, but each has its own advantages and shortcomings. A novel technique is proposed based on the combination of computergenerated holography and reflection holography, which can overcome the limitation of optical Both of the computergenerated holograms and optical holograms can be applied to a threedimensional display, but each has its own advantages and shortcomings. A novel technique is proposed based on the combination of computergenerated holography and reflection holography, which can overcome the limitation of optical holography. This technique can record realexisting objects and virtual objects, and achieve the reconstruction image by white light illumination. A 3D scanner is used to obtain 3D data of a realexisting object and calculate Fresnel holographic transmission distribution by point cloud algorithm. The Fresnel hologram is outputted by a holographic microfilming system. And, the reconstructed real image H1 of the computing hologram is used as the recording object for optical reflection hologram. The principle of this technique is explained in detail and the experimental results demonstrate that the technique is feasible..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 591 (2012)
Dim Small Targets Detection with Noise Suppression Utilizing Adjacent Relevant Pixels Information
HUANG Hewen, and Jin Tao
An infrared dim target detecting algorithm called the adjacent relevant pixels detection is proposed. Firstly, an adaptive local threshold is used to detect bright pixels, and then eliminate the noise with the information of adjacent relevant pixels. The remaining suspicious pixels are enhanced by the relevant bright pAn infrared dim target detecting algorithm called the adjacent relevant pixels detection is proposed. Firstly, an adaptive local threshold is used to detect bright pixels, and then eliminate the noise with the information of adjacent relevant pixels. The remaining suspicious pixels are enhanced by the relevant bright pixels, by which the noise is suppressed again and considerable SNR gains are obtained. ARPD method is compared with classic TopHat transformations with and without 8neigboorhood clustering. The target point in images processed by ARPD method receives high signaltoclutter ratio gain, and the detectability of the target is enhanced..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 596 (2012)
Subjective Quality Evaluation Method of Stereo Image
ZHANG Yingjing, LI Sumei, WEI Jinjin, and ZANG Yanjun
Quality evaluation method of stereo image plays an important role in image compression , processing and communications, and objective quality evaluation method of stereo imagedepends on the subjective evaluation. Based on the characteristics of the human eye stereo vision,a new subjective evaluation is proposed. In thiQuality evaluation method of stereo image plays an important role in image compression , processing and communications, and objective quality evaluation method of stereo imagedepends on the subjective evaluation. Based on the characteristics of the human eye stereo vision,a new subjective evaluation is proposed. In this paper, six aspects in details are described: building stereo image library, the choice of evaluators,description of experimentcondition, training and testing evaluators, dataprocessing and analysis of experiment result. The experiments results are the scores of stereo image, which can be assessed by different evaluators and processed by the theory of mathematical statistics. The resultsuggests that subjective quality evaluation method isreasonable and can state stereo image quality accurately..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 602 (2012)
Characteristics of Degree of Polarization of Backscattering Light in Scattering Medium at Different Wavelengths
CAO Xianping, and SUN Ping
The degree of polarization (DOP) of backscattering light in intralipid were measured based on Stokes vector. The characteristics of DOP were investigated when the interaction between polarized light and scattering midum were taken into account . The polarized light included three different wavelengths of 532 nm, 650 nmThe degree of polarization (DOP) of backscattering light in intralipid were measured based on Stokes vector. The characteristics of DOP were investigated when the interaction between polarized light and scattering midum were taken into account . The polarized light included three different wavelengths of 532 nm, 650 nm and 780nm. The diameter of scattering particle was 325 nm. Experimental results show that the circularly polarized component in backscattering light is more than the linearly polarized component for linearly polarized incident light of wavelength of 532 nm. However, this conclusion is reverse for wavelength of 780 nm. In addition, the circularly polarized component is more than the linearly polarized component for three different wavelengths when circularly polarized incident light was used. Furthermore, the total DOP value of 532 nm was larger than that of 650 nm and 780 nm respectively. Linearly polarized light maintained polarization better than circularly polarized light, however, the penetrating depth through scattering medium of polarized light was short. So the imaging used backscattering light can be applied to image superficial objects. Besides, the imaging quality can be improved if the wavelength of incident light is a little bigger than the diameter of scattering particle..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 608 (2012)
Title Polarized Light Transmittance of Magnetic Fluids Assigned to the Coupling of Geometric Shadowing Effect and Faraday Rotation Effect
PU Shengli, JI Hongzhu, YU Guojun, and WANG Xiang
The polarized light transmittance of magnetic fluids under longitudinal magnetic field and the influence of magnetic fluids concentration, dielectric constants of the remanent liquid phase within the magnetic fluids, the ratio of dipole moment to the thermal energy of single magnetic nanoparticle and the number of magnThe polarized light transmittance of magnetic fluids under longitudinal magnetic field and the influence of magnetic fluids concentration, dielectric constants of the remanent liquid phase within the magnetic fluids, the ratio of dipole moment to the thermal energy of single magnetic nanoparticle and the number of magnetic nanoparticles per agglomeration are investigated numerically according to the analytical expression when considering both the geometric shadowing effect and the Faraday rotation effect. Theoretical results indicate that the magnetic fluids concentration, dielectric constants of the remanent liquid phase within the magnetic fluids and the ratio of dipole moment to the thermal energy of the single magnetic nanoparticle affect the polarized light transmittance apparently. The polarized light transmittance of magnetic fluids increases linearly or oscillates with the strength of the longitudinal magnetic field for low or high concentration samples, respectively. In certain ranges, the polarized light transmittance of magnetic fluids increases with dielectric constants of the remanent liquid phase and the ratio of dipole moment to the thermal energy of single magnetic nanoparticle. While the polarized light transmittance is almost independent of the number of magnetic nanoparticles per agglomeration. The distinct difference of the parameterdependent polarized light transmittance at low and high magnetic field regions is obtained. The applications to several photonic devices based on the polarized light transmittance of magnetic fluids under longitudinal magnetic field are proposed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 614 (2012)
THz Scattering Property for a Magnetized Cold Plasma Sphere
LI Yingle, LI Jin, WANG Mingjun, and DONG Qunfeng
Based on that the potential functions and medium parameter are irrelative and expanding the electric fields inside & outside the anisotropic medium target into series, the nthorder expressions both of scattering field from an anisotropic medium target and its inner elelctric field are developed. The transformationBased on that the potential functions and medium parameter are irrelative and expanding the electric fields inside & outside the anisotropic medium target into series, the nthorder expressions both of scattering field from an anisotropic medium target and its inner elelctric field are developed. The transformation of the dielectric constant tensor is presented. When a plane electromagnetic wave incident in arbitrary direction, a general relation between the unit vector in propagation and that in polarization is expressed. Taking the magnetized cold plasma as an example, the first order scattering is developed and the error induced by the second order field is evaluated. In the THz wave band and optical wave band, the obtained result is simulated. Simulation results show that the differential scattering change sensitively with operating frequency and the polarization etc.; the nondiagonal elements of the tensor have no influence on the scattering; when the wave length and the size of the target are given, the simulations are correct in THz wave band and validate in other wave band..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 619 (2012)
Analysis and Revision on the Static Doublegain Hadamard Spectrometer
HAO Peng, and WU Yihui
To obtain both high sensitivity and high throughput when measuring at the same time, a static doublegain Hadamard spectrometer is introduced, based on microslit array. The principle and instrument structure of static doublegain Hadamard spectrometer are described, and spectra aliasing caused by Hadamard encoding masTo obtain both high sensitivity and high throughput when measuring at the same time, a static doublegain Hadamard spectrometer is introduced, based on microslit array. The principle and instrument structure of static doublegain Hadamard spectrometer are described, and spectra aliasing caused by Hadamard encoding mask is investigated. The relationship between spectral offset and the spatial offset of incident slit is obtained. For a given wavelength spectrum, the spatial offset caused by the spatial offset of incident slit is also calculated in theory. The simulation results show that this method has no complex computation, with fast correction, and is easy in program realization..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 623 (2012)
Spectroscopic Studies on the Edible Flavoring in Terahertz Range
YANG Chen, TIAN Lu, and ZHAO Kun
Edible flavor is one of the essential materials in cooking process and daily life, so the identification and testing of edible flavor become particularly important in food safety. In this paper, the optical property and spectroscopy of edible flavor were studied based on the terahertz timedomain spectroscopy (THzTDS)Edible flavor is one of the essential materials in cooking process and daily life, so the identification and testing of edible flavor become particularly important in food safety. In this paper, the optical property and spectroscopy of edible flavor were studied based on the terahertz timedomain spectroscopy (THzTDS). By applying a numerical fast Fourier transform (FFT), the optical constants of black pepper, white pepper, Chinese prickly ash, aniseed, ginger, liquorice, bay leaf, five spices and thirteen spices were calculated. Different kinds of flavors have their unique characteristic absorption features. The absorption spectra of each kind sample increase in monotonic form and are not equal in the slope of curve in the range of 0.2~1.25 THz. However, in the range of 1.25~2.0 THz, edible flavoring shows different absorption features. The refractive indices of samples vary in the range of 1.3~1.8. The refractive indices of samples appear anomalous dispersion suggested that the resonance process is related with optical absorption, which also exhibit absorption peaks similar to those in the curve of absorption coefficient. THzTDS technology can be used for qualitative analysis of different kinds of flavoring according to their characteristic spectral features. The results indicated that THzTDS can be used to establish the fingerprint database of edible flavoring..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 5, 627 (2012)
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