Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical ...Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical systems or complex metasurface structures,which cause the system complexity with unessential energy loss.Recently,filterless on-chip full-Stokes polarimeters have been demonstrated by using optical anisotropic materials which are able to detect the circularly polarized light.Nevertheless,those on-chip full-Stokes polarimeters have either the limited detection wavelength range or relatively poor device performance that need to be further improved.Here,we report the high performance broadband full-Stokes polarimeters based on rhenium disulfide(ReS_(2)).While the anisotropic structure of the ReS_(2)introduces the in-plane optical anisotropy for linearly polarized light(LP)detection,Schottky contacts formed by the ReS_(2)-Au could break the symmetry,which can detect circularly polarized(CP)light.By building a proper model,all four Stokes parameters can be extracted by using the ReS_(2)nanobelt device.The device delivers a photoresponsivity of 181 A/W,a detectivity of 6.8×10^(10)Jones and can sense the four Stokes parameters of incident light within a wide range of wavelength from 565-800 nm with reasonable average errors.We believe our study provides an alternative strategy to develop high performance broadband on-chip full-Stokes polarimeters.展开更多
We report on using synthetic silicon for a high-precision X-ray polarimeter comprising a polarizer and an analyzer,each based on a monolithic channel-cut crystal used at multiple Brewster reflections with a Bragg angl...We report on using synthetic silicon for a high-precision X-ray polarimeter comprising a polarizer and an analyzer,each based on a monolithic channel-cut crystal used at multiple Brewster reflections with a Bragg angle very close to 45°.Experiments were performed at the BL09B bending magnet beamline of the Shanghai Synchrotron Radiation Facility using a Si(800)crystal at an X-ray energy of 12.914 keV.A polarization purity of 8.4×10^(-9)was measured.This result is encouraging,as the measured polarization purity is the best-reported value for the bending magnet source.Notably,this is the firstly systematic study on the hard X-ray polarimeter in China,which is crucial for exploring new physics,such as verifying vacuum birefringence.展开更多
A multi-channel polarimeter-interferometer has been developed on the Keda Torus eXperiment(KTX)for the study of equilibrium dynamics and internal magnetic fluctuations.A three-wave technique based on terahertz solid-s...A multi-channel polarimeter-interferometer has been developed on the Keda Torus eXperiment(KTX)for the study of equilibrium dynamics and internal magnetic fluctuations.A three-wave technique based on terahertz solid-state sources(-650 GHz)is applied for simultaneous measurements of electron density and Faraday rotation angle.The output power of the microwave source is 2 mW.Faraday rotation effect using a rotating wave plate is tested with phase noise less than 0.8°,and the density phase noise is less than 0.9°.Measurement of Faraday rotation angle and density for discharges on KTX have demonstrated high sensitivity to internal MHD activities.展开更多
Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Pup...Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Puplett interferometer(MPI)polarimeter to probe the peripheral magnetic fields generated in the common magnetic reconnection configuration,two separated coplanar plane targets,in laser-target interaction.We introduce a new method that can obtain polarization information from the interference pattern instead of the sinusoidal function fitting of the intensity.A bidirectional magnetic field is observed from the side view,which is consistent with the magneto-hydro-dynamical(MHD)simulation results of self-generated magnetic field reconnection.We find that the cancellation of reverse magnetic fields after averaging and integration along the observing direction could reduce the magnetic field strength by one to two orders of magnitude.It indicates that imaging resolution can significantly affect the accuracy of measured magnetic field strength.展开更多
The detection of the state of polarization(SOP)of light is essential for many optical applications.However,cost-effective SOP measurement is a challenge due to the complexity of conventional methods and the poor trans...The detection of the state of polarization(SOP)of light is essential for many optical applications.However,cost-effective SOP measurement is a challenge due to the complexity of conventional methods and the poor transferability of new methods.We propose a straightforward,low-cost,and portable SOP measurement system based on the multimode fiber speckle.A convolutional neural network is utilized to establish the mapping relationship between speckle and Stokes parameters.The lowest root-mean-square error of the estimated SOP on the Poincarésphere can be 0.0042.This method is distinguished by its low cost,clear structure,and applicability to different wavelengths with high precision.The proposed method is of great value in polarization-related applications.展开更多
In this paper, we present a simple Stokes parameter measurement method for a rotating quarter-wave plate polarimeter. This method is used to construct a model to describe the principle of how the magnitudes of errors ...In this paper, we present a simple Stokes parameter measurement method for a rotating quarter-wave plate polarimeter. This method is used to construct a model to describe the principle of how the magnitudes of errors influence the deviation of the output light Stokes parameter, on the basis of accuracy analysis of the retardance error of the quarter-wave plate, the misalignment of the analyzing polarizer, and the phase shift of the measured signals, which will help us to determine the magnitudes of these errors and then to acquire the correct results of Stokes parameters. The method is validated by the experiments on left-handed circularly polarized and linear horizontal polarization beams. With the improved method, the maximum measurement deviations of Stokes parameters for these two different polarized states are reduced from 2.72% to 2.68%, and from 3.83% to 1.06% respectively. Our results demonstrate that the proposed method can be used as a promising approach to Stokes parameter measurement for a rotating quarter-wave plate polarimeter.展开更多
The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and wi...The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and will be applied for magnetic field measurement in the first space-based solar observatory satellite developed by China,Advanced Space-based Solar Observatory.However,the liquid crystals based Stokes polarimeter in space is not a mature technology.Therefore,it is of great scientific significance to study the control method and characteristics of the device.The retardation produced by a liquid crystal variable retarder is sensitive to the temperature,and the retardation changes 0.09°per 0.10℃.The error in polarization measurement caused by this change is 0.016,which affects the accuracy of magnetic field measurement.In order to ensure the stability of its performance,this paper proposes a high-precision temperature control system for liquid crystals based Stokes polarimeter in space.In order to optimize the structure design and temperature control system,the temperature field of liquid crystals based Stokes polarimeter is analyzed by the finite element method,and the influence of light on the temperature field of the liquid crystal variable retarder is analyzed theoretically.By analyzing the principle of highprecision temperature measurement in space,a high-precision temperature measurement circuit based on integrated operational amplifier,programmable amplifier and 12 bit A/D is designed,and a high-precision space temperature control system is developed by applying the integral separation PI temperature control algorithm and PWM driving heating films.The experimental results show that the effect of temperature control is accurate and stable,whenever the liquid crystals based Stokes polarimeter is either in the air or vacuum.The temperature stability is within±0.0150℃,which demonstrates greatly improved stability for the liquid crystals based Stokes polarimeter.展开更多
Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, wh...Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than 5.7 × 10-3 can be achieved by using a single short-exposure image, while an accuracy on the order of 10-5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.展开更多
A Mossbauer polarimeter consists of a gamma ray source (polarizer), transmitter (sample to be analyzed), analyzer and automatic counting system. This equipment was used to observe the Mossbauer Faraday effect in non-s...A Mossbauer polarimeter consists of a gamma ray source (polarizer), transmitter (sample to be analyzed), analyzer and automatic counting system. This equipment was used to observe the Mossbauer Faraday effect in non-stoichiometric Fe3O4. Experimental results demonstrated that electronic hopping above the Verwey temperature between Fe2+- Fe3+ ions on the octahedral sites is a only localized phenomenon and the recoilless fractions of 57Fe nuclei in Fe3-vO4 (v=0.02) are 0.71 for A sites and 0.62 for B sites, respectively.展开更多
A three-wave based laser polarimeter/interferometer and a CO_(2)laser dispersion interferometer are used to determine the electron and current density profiles on a Chinese fusion engineering test reactor(CFETR).Radia...A three-wave based laser polarimeter/interferometer and a CO_(2)laser dispersion interferometer are used to determine the electron and current density profiles on a Chinese fusion engineering test reactor(CFETR).Radiation shielding is designed for the combination of polarimeter/interferometer and CO_(2)dispersion interferometer.Furthermore,neutronics models of the two systems are developed based on the engineering-integrated design of CFETR polarimeter/interferometer and CO_(2)dispersion interferometer and the major material components of CFETR.The polarimeter/interferometer and CO_(2)dispersion interferometer's neutron and photon transport simulations were performed using the Monte Carlo neutral transport code to determine the energy deposition and neutron energy spectrum of the optical mirrors.The energy depositions of the first mirrors on the polarimeter/interferometer are reduced by three orders with the whole shielding.Since the mirrors of CO_(2)dispersion interferometer are very close to the diagnostic first wall,shielding space is limited and the CO_(2)dispersion interferometer energy deposition is higher than that of the polarimeter/interferometer.The dose rate after shutdown106s in the back-drawer structure has been estimated to be 83μSv h^(-1)when the radiation shield is filled in the diagnostic shielding modules,which is below the design threshold of 100μSv h^(-1).Radiation shielding design plays a key role in successfully applying polarimeter/interferometer and CO_(2)dispersive interferometer in CFETR.展开更多
A new GaAs（100） spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shie...A new GaAs（100） spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shielded by a box and a cylinder made of nickel-iron-molybdenum soft magnetic alloy without Helmholtz coil arrangement. And a uniformly distributed residual magnetic field of less than 5 × 10^-7T is obtained near the collision area. The spin polarized electron beam is transmitted and focused onto collision point from photocathode by a set of electron optics with more than 25% transmission 95 cm distance through an 1 mm diameter aperture. Construction and operation of the apparatus, such as vacuum and magnetic shielding system, photocathode, laser optics, electron optics and polarimeter are discussed. The polarization of the spin polarized electron beam is determined to be 30.8 ±3.5% measured with a He optical polarimeter.展开更多
A multichannel methanoic acid （HCOOH, λ=432.5 μm） laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide （HCN, λ=337 μm） laser interferometer in the HL-2A tokamak....A multichannel methanoic acid （HCOOH, λ=432.5 μm） laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide （HCN, λ=337 μm） laser interferometer in the HL-2A tokamak. A conventional Michelson-type interometer is used for the electron density measurement, and a Dodel-Kunz-type polarimeter is used for the Faraday rotation effect measurement, respectively. Each HCOOH laser can produce a linearly polarized radiation at a power lever of -30 mW, and a power stability 〈10% in 50 rain. A beam waist （diameter d0 ≈12.0 mm, about 200 mm away from the outlet） is finally determined through a chopping modulation technique. The latest optical layout of the interferometer/polarimeter has been finished, and the hardware data processing system based on the fast Fourier transform phase- comparator technique is being explored. In order to demonstrate the feasibility of the diagnostic scheme, two associated bench simulation experiments were carried out in the laboratory, in which the plasma was simulated by a piece of polytetrafluoroethene plate, and the Faraday rotation effect was simulated by a rotating half-wave plate. Simulation results agreed well with the initial experimental conditions. At present, the HCOOH laser interferometer/polarimeter system is being assembled on HL-2A, and is planned to be applied in the 2014-2015 experimental campaign.展开更多
The J-TEXT three-wave polarimeter-interferometer system(POLARIS),which measures timespace distribution of electron density and current density,has been optimized with both the optical system and the equilibrium recons...The J-TEXT three-wave polarimeter-interferometer system(POLARIS),which measures timespace distribution of electron density and current density,has been optimized with both the optical system and the equilibrium reconstruction method.The phase resolution of a Faraday rotation angle has been improved from 0.1 to 0.06 degree in chords from–0.18 to 0.18 m(plasma minor radius),and the sawtooth oscillation behavior has been detected by Faraday rotation angle measurement.By combining the POLARIS measured data and the equilibrium and fitting code(EFIT),an upgraded equilibrium reconstruction method has been developed,which provides a more accurate temporal and spatial distribution of current density and electron density.By means of the optimized POLARIS and improved equilibrium reconstruction,variations of profiles with increasing density have been carried out,under both Ohmic and electron cyclotron resonance heating discharges.展开更多
Polarimetry plays an important role in investigating physical properties for celestial objects. We present a polarimeter named YFPOL for the Cassegrain focus of the Lijiang 2.4 m Telescope(LJT) of Yunnan Observatories...Polarimetry plays an important role in investigating physical properties for celestial objects. We present a polarimeter named YFPOL for the Cassegrain focus of the Lijiang 2.4 m Telescope(LJT) of Yunnan Observatories, Chinese Academy of Sciences. YFPOL is a traditional single-beam polarimeter with a rotating polarizer. As the focal-reducer instrument Yunnan Faint Object Spectrograph and Camera(YFOSC) is always positioned on the Cassegrain focal plane of LJT, we develop two sets of ultra-thin(thickness <12 mm) polarizer rotation control systems with wireless charging and control functions, which are suitable for mounting on the two front-wheels of YFOSC. One set is used as the polarimetric calibration unit, and the other is for the polarimetric modulation unit. Both of the polarizers have an ultra-high contrast ratio of 1,000,000:1 in the optical band. We investigate the instrumental polarization characteristics(IPCs) in the full field of view that is transferred from YFOSC. Furthermore, we identify that the IPCs change when the Cassegrain axis rotates. The spurious polarization from the IPCs can be effectively minimized by flat-fielding using the unpolarized domeflat, when the Cassegrain rotation angle is the same or nearest to that of the polarization observation. We develop a quasiautomatic pipeline for YFPOL and its effectiveness has been verified by tests of the polarimetric observation with blazar S5 0716+714. The calibration is performed by observing the zero-polarized and highly-polarized standard stars. We successfully reach high precision polarization in the 7’ field of view, and the systematic uncertainty is below 0.8% for a V = 11.68 target with a 10 s exposure. The instrument polarization angle offset is 2°. 6. YFPOL is not only a simple polarimeter, but also a spectropolarimeter with grisms that can be considered in the future.展开更多
We report the design concept and performance of a compact,lightweight and economical imaging polarimeter,the Triple Range Imager and POLarimeter(TRIPOL),capable of simultaneous optical imagery and polarimetry.TRIPOL s...We report the design concept and performance of a compact,lightweight and economical imaging polarimeter,the Triple Range Imager and POLarimeter(TRIPOL),capable of simultaneous optical imagery and polarimetry.TRIPOL splits the beam in wavelengths from 400 to 830 nm into g′-,r′-and i′-bands with two dichroic mirrors,and measures polarization with an achromatic half-waveplate and a wire grid polarizer.The simultaneity makes TRIPOL a useful tool for small telescopes for the photometry and polarimetry of time variable and wavelength dependent phenomena.TRIPOL is designed for a Cassegrain telescope with an aperture of^1 m.This paper presents the engineering considerations of TRIPOL and compares the expected with observed performance.Using the Lulin 1-m telescope and 100 seconds of integration,the limiting magnitudes are g′~19.0 mag,r′~18.5 mag and i′~18.0 mag with a signal-to-noise ratio of 10,in agreement with design expectation.The instrumental polarization is measured to be^0.3%in the three bands.Two applications,one to the star-forming cloud IC 5146 and the other to the young variable GM Cep,are presented as demonstrations.展开更多
PolarLight is a space-borne X-ray polarimeter that measures the X-ray polarization via electron tracking in an ionization chamber.It is a collimated instrument and thus suffers from the background on the whole detecto...PolarLight is a space-borne X-ray polarimeter that measures the X-ray polarization via electron tracking in an ionization chamber.It is a collimated instrument and thus suffers from the background on the whole detector plane.The majority of background events are induced by high energy charged particles and show ionization morphologies distinct from those produced by X-rays of interest.Comparing on-source and off-source observations,we find that the two datasets display different distributions on image properties.The boundaries between the source and background distributions are obtained and can be used for background discrimination.Such a means can remove over 70%of the background events measured with PolarLight.This approaches the theoretical upper limit of the background fraction that is removable and justifies its effectiveness.For observations with the Crab nebula,the background contamination decreases from 25%to 8%after discrimination,indicative of a polarimetric sensitivity of around 0.2 Crab for PolarLight.This work also provides insights into future X-ray polarimetric telescopes.展开更多
The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry ...The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.展开更多
The method of plasma current profile reconstruction using the polarimeter/interferometer（POINT） data from a simulated equilibrium is explored and validated.It is shown that the safety factor（q） profile can be gene...The method of plasma current profile reconstruction using the polarimeter/interferometer（POINT） data from a simulated equilibrium is explored and validated.It is shown that the safety factor（q） profile can be generally reconstructed from the external magnetic and POINT data.The reconstructed q profile is found to reasonably agree with the initial equilibriums.Comparisons of reconstructed q and density profiles using the magnetic data and the POINT data with 3%,5%and 10%random errors are investigated.The result shows that the POINT data could be used to a reasonably accurate determination of the q profile.展开更多
Polarimeter is a vital precision tool used for measuring optical parameters through polarization variations.Among the wide range of application fields,the precise measurement of photosensitive materials is an unavoida...Polarimeter is a vital precision tool used for measuring optical parameters through polarization variations.Among the wide range of application fields,the precise measurement of photosensitive materials is an unavoidable task but faces immense obstacles due to the excessive input photons.Facing this situation,introducing a quantum source into the classical precision measurement system is a feasible way to enhance the detection accuracy under the low illumination regime.In this work,we employ polarization-entangled photon pairs in the classical polarimeter to precisely detect the relative phase retardance of uniform anisotropic media.The experimental results show that the accuracy can reach the nanometer scale at extremely low input intensity,and the stabilities are within 0.4%for all samples.Our work paves the way for polarization measurement at low incident light intensity,with potential applications in measuring photosensitive materials and remote monitoring scenarios.展开更多
Randomness describes one inherent property of self-assembled metamaterials and greatly limits the practical applications of metamaterials based on bottom-up techniques,such as the microsphere lithography technique.Her...Randomness describes one inherent property of self-assembled metamaterials and greatly limits the practical applications of metamaterials based on bottom-up techniques,such as the microsphere lithography technique.Herein,by subtly utilizing the randomness in long-range disorder metasurfaces,we demonstrate a high-performance one-shot full-Stokes polarimeter in the visible waveband.The long-range disorder metasurfaces,i.e.,chiral shells,were realized by depositing Ag on the self-assembled microsphere monolayer comprised of many micro-domains of random lattice directions and areas.The distinct optical anisotropy and chirality in different micro-domains can result in distinct photo-currents to the photodetector array placed underneath upon the injection of polarized lights.Through establishing the mapping relationship S=f[/]between the detected photo-currents/and the states of polarization(SoP)S with the convolutional neural network(CNN)algorithm,we realize a high-precision full-Stokes polarimeter in the waveband ranging from 500 to 650 nm,and the minimum mean square errors(MSEs)can reach about 0.37%(S_(1)),0.33%(S_(2)),and 0.19%(S_(3))at 566 nm.The average MSEs in the investigated waveband are 0.49%(S_(1)),0.45%(S_(2)),and 0.31%(S_(3)),respectively.We have systematically investigated the macro-and micro-optical properties of chiral shells,the optical randomness of chiral shells in different domains,the reference SoP number,the exposure time and pixel number of the CCD,as well as the reliability and stability of the system.展开更多
基金the support from the National Key Research and Development Program of China(2022YFB2803900 and 2018YFA0704403)NSFC(62074064)。
文摘Full-Stokes polarimeters can detect the polarization states of light,which is critical for the next-generation optical and optoelectronic systems.Traditional full-Stokes polarimeters are either based on bulky optical systems or complex metasurface structures,which cause the system complexity with unessential energy loss.Recently,filterless on-chip full-Stokes polarimeters have been demonstrated by using optical anisotropic materials which are able to detect the circularly polarized light.Nevertheless,those on-chip full-Stokes polarimeters have either the limited detection wavelength range or relatively poor device performance that need to be further improved.Here,we report the high performance broadband full-Stokes polarimeters based on rhenium disulfide(ReS_(2)).While the anisotropic structure of the ReS_(2)introduces the in-plane optical anisotropy for linearly polarized light(LP)detection,Schottky contacts formed by the ReS_(2)-Au could break the symmetry,which can detect circularly polarized(CP)light.By building a proper model,all four Stokes parameters can be extracted by using the ReS_(2)nanobelt device.The device delivers a photoresponsivity of 181 A/W,a detectivity of 6.8×10^(10)Jones and can sense the four Stokes parameters of incident light within a wide range of wavelength from 565-800 nm with reasonable average errors.We believe our study provides an alternative strategy to develop high performance broadband on-chip full-Stokes polarimeters.
基金supported by the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)the National Natural Science Foundation of China(No.12205360)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2018297)。
文摘We report on using synthetic silicon for a high-precision X-ray polarimeter comprising a polarizer and an analyzer,each based on a monolithic channel-cut crystal used at multiple Brewster reflections with a Bragg angle very close to 45°.Experiments were performed at the BL09B bending magnet beamline of the Shanghai Synchrotron Radiation Facility using a Si(800)crystal at an X-ray energy of 12.914 keV.A polarization purity of 8.4×10^(-9)was measured.This result is encouraging,as the measured polarization purity is the best-reported value for the bending magnet source.Notably,this is the firstly systematic study on the hard X-ray polarimeter in China,which is crucial for exploring new physics,such as verifying vacuum birefringence.
基金supported by National Natural Science Foundation of China(No.12175227)the Fundamental Research Funds for the Central Universities(No.USTC 20210079)the Collaborative Innovation Program of Hefei Science Center,CAS(No.2022HSC-CIP022)。
文摘A multi-channel polarimeter-interferometer has been developed on the Keda Torus eXperiment(KTX)for the study of equilibrium dynamics and internal magnetic fluctuations.A three-wave technique based on terahertz solid-state sources(-650 GHz)is applied for simultaneous measurements of electron density and Faraday rotation angle.The output power of the microwave source is 2 mW.Faraday rotation effect using a rotating wave plate is tested with phase noise less than 0.8°,and the density phase noise is less than 0.9°.Measurement of Faraday rotation angle and density for discharges on KTX have demonstrated high sensitivity to internal MHD activities.
基金Project supported by the National Key R&D Program of China (Grant Nos.2022YFA1603200 and 2022YFA1603203)the National Natural Science Foundation of China (Grant Nos.12075030,12135001,12175018,and 12325305)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA25030700)the Research Grants Council of Hong (Grant No.14307118)the Youth Interdisciplinary Team (Grant No.JCTD-2022-05)supported by the China Postdoctoral International Exchange Program。
文摘Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Puplett interferometer(MPI)polarimeter to probe the peripheral magnetic fields generated in the common magnetic reconnection configuration,two separated coplanar plane targets,in laser-target interaction.We introduce a new method that can obtain polarization information from the interference pattern instead of the sinusoidal function fitting of the intensity.A bidirectional magnetic field is observed from the side view,which is consistent with the magneto-hydro-dynamical(MHD)simulation results of self-generated magnetic field reconnection.We find that the cancellation of reverse magnetic fields after averaging and integration along the observing direction could reduce the magnetic field strength by one to two orders of magnitude.It indicates that imaging resolution can significantly affect the accuracy of measured magnetic field strength.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB2800902)the National Natural Science Foundation of China(Grant No.62225110)+1 种基金the Key Research and Development Program of Hubei Province(No.2022BAA001)the Innovation Fund of WNLO.
文摘The detection of the state of polarization(SOP)of light is essential for many optical applications.However,cost-effective SOP measurement is a challenge due to the complexity of conventional methods and the poor transferability of new methods.We propose a straightforward,low-cost,and portable SOP measurement system based on the multimode fiber speckle.A convolutional neural network is utilized to establish the mapping relationship between speckle and Stokes parameters.The lowest root-mean-square error of the estimated SOP on the Poincarésphere can be 0.0042.This method is distinguished by its low cost,clear structure,and applicability to different wavelengths with high precision.The proposed method is of great value in polarization-related applications.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2015AA123702)the National Natural Science Foundation of China(Grant No.61505222)
文摘In this paper, we present a simple Stokes parameter measurement method for a rotating quarter-wave plate polarimeter. This method is used to construct a model to describe the principle of how the magnitudes of errors influence the deviation of the output light Stokes parameter, on the basis of accuracy analysis of the retardance error of the quarter-wave plate, the misalignment of the analyzing polarizer, and the phase shift of the measured signals, which will help us to determine the magnitudes of these errors and then to acquire the correct results of Stokes parameters. The method is validated by the experiments on left-handed circularly polarized and linear horizontal polarization beams. With the improved method, the maximum measurement deviations of Stokes parameters for these two different polarized states are reduced from 2.72% to 2.68%, and from 3.83% to 1.06% respectively. Our results demonstrate that the proposed method can be used as a promising approach to Stokes parameter measurement for a rotating quarter-wave plate polarimeter.
基金the National Natural Science Foundation of China(Grant Nos.11427803,11427901 and 11773040)the Strategic Pioneer Program on Space Science,Chinese Academy of Sciences(CAS)(XDA04061002 and XDA15010800)the Public Technology Service Center,National Astronomical Observatories of CAS(829011V01)。
文摘The magnetic field is one of the most important parameters in solar physics,and a polarimeter is the key device to measure the solar magnetic field.Liquid crystals based Stokes polarimeter is a novel technology,and will be applied for magnetic field measurement in the first space-based solar observatory satellite developed by China,Advanced Space-based Solar Observatory.However,the liquid crystals based Stokes polarimeter in space is not a mature technology.Therefore,it is of great scientific significance to study the control method and characteristics of the device.The retardation produced by a liquid crystal variable retarder is sensitive to the temperature,and the retardation changes 0.09°per 0.10℃.The error in polarization measurement caused by this change is 0.016,which affects the accuracy of magnetic field measurement.In order to ensure the stability of its performance,this paper proposes a high-precision temperature control system for liquid crystals based Stokes polarimeter in space.In order to optimize the structure design and temperature control system,the temperature field of liquid crystals based Stokes polarimeter is analyzed by the finite element method,and the influence of light on the temperature field of the liquid crystal variable retarder is analyzed theoretically.By analyzing the principle of highprecision temperature measurement in space,a high-precision temperature measurement circuit based on integrated operational amplifier,programmable amplifier and 12 bit A/D is designed,and a high-precision space temperature control system is developed by applying the integral separation PI temperature control algorithm and PWM driving heating films.The experimental results show that the effect of temperature control is accurate and stable,whenever the liquid crystals based Stokes polarimeter is either in the air or vacuum.The temperature stability is within±0.0150℃,which demonstrates greatly improved stability for the liquid crystals based Stokes polarimeter.
基金funded by the National Natural Science Foundation of China(NSFC,Grant Nos.11661161011,11433007,11220101001,11328302,11373005 and 11303064)the Opening Project of Key Laboratory of Astronomical Optics&Technology,Nanjing Institute of Astronomical Optics&Technology,Chinese Academy of Sciences(CASKLAOT-KF201606)+4 种基金the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDA04075200)the special fund for astronomy of CAS(2015–2016)the special funding for Young Researcher of Nanjing Institute of Astronomical Optics&Technologythe International Partnership Program of the Chinese Academy of Sciences(Grant No.114A32KYSB20160018)the Mt.Cuba Astronomical Foundation
文摘Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than 5.7 × 10-3 can be achieved by using a single short-exposure image, while an accuracy on the order of 10-5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.
文摘A Mossbauer polarimeter consists of a gamma ray source (polarizer), transmitter (sample to be analyzed), analyzer and automatic counting system. This equipment was used to observe the Mossbauer Faraday effect in non-stoichiometric Fe3O4. Experimental results demonstrated that electronic hopping above the Verwey temperature between Fe2+- Fe3+ ions on the octahedral sites is a only localized phenomenon and the recoilless fractions of 57Fe nuclei in Fe3-vO4 (v=0.02) are 0.71 for A sites and 0.62 for B sites, respectively.
基金the National MCF Energy R&D Program of China(Nos.2019YFE03040003 and 2017YFE0301205)Key Program of Research and Development of Hefei Science Center,CAS(No.2019HSC-KPRD001)supported in part by the Collaborative Research Program of the Research Institute for Applied Mechanics,Kyushu University。
文摘A three-wave based laser polarimeter/interferometer and a CO_(2)laser dispersion interferometer are used to determine the electron and current density profiles on a Chinese fusion engineering test reactor(CFETR).Radiation shielding is designed for the combination of polarimeter/interferometer and CO_(2)dispersion interferometer.Furthermore,neutronics models of the two systems are developed based on the engineering-integrated design of CFETR polarimeter/interferometer and CO_(2)dispersion interferometer and the major material components of CFETR.The polarimeter/interferometer and CO_(2)dispersion interferometer's neutron and photon transport simulations were performed using the Monte Carlo neutral transport code to determine the energy deposition and neutron energy spectrum of the optical mirrors.The energy depositions of the first mirrors on the polarimeter/interferometer are reduced by three orders with the whole shielding.Since the mirrors of CO_(2)dispersion interferometer are very close to the diagnostic first wall,shielding space is limited and the CO_(2)dispersion interferometer energy deposition is higher than that of the polarimeter/interferometer.The dose rate after shutdown106s in the back-drawer structure has been estimated to be 83μSv h^(-1)when the radiation shield is filled in the diagnostic shielding modules,which is below the design threshold of 100μSv h^(-1).Radiation shielding design plays a key role in successfully applying polarimeter/interferometer and CO_(2)dispersive interferometer in CFETR.
基金Project supported by the National Natural Science Foundation of China （Grant No 10134010）.
文摘A new GaAs（100） spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shielded by a box and a cylinder made of nickel-iron-molybdenum soft magnetic alloy without Helmholtz coil arrangement. And a uniformly distributed residual magnetic field of less than 5 × 10^-7T is obtained near the collision area. The spin polarized electron beam is transmitted and focused onto collision point from photocathode by a set of electron optics with more than 25% transmission 95 cm distance through an 1 mm diameter aperture. Construction and operation of the apparatus, such as vacuum and magnetic shielding system, photocathode, laser optics, electron optics and polarimeter are discussed. The polarization of the spin polarized electron beam is determined to be 30.8 ±3.5% measured with a He optical polarimeter.
基金supported by the National Magnetic Confinement Fusion Science Programs of China(Nos.2010GB101002 and 2014GB109001)National Natural Science Foundation of China(Nos.11075048 and 11275059)
文摘A multichannel methanoic acid （HCOOH, λ=432.5 μm） laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide （HCN, λ=337 μm） laser interferometer in the HL-2A tokamak. A conventional Michelson-type interometer is used for the electron density measurement, and a Dodel-Kunz-type polarimeter is used for the Faraday rotation effect measurement, respectively. Each HCOOH laser can produce a linearly polarized radiation at a power lever of -30 mW, and a power stability 〈10% in 50 rain. A beam waist （diameter d0 ≈12.0 mm, about 200 mm away from the outlet） is finally determined through a chopping modulation technique. The latest optical layout of the interferometer/polarimeter has been finished, and the hardware data processing system based on the fast Fourier transform phase- comparator technique is being explored. In order to demonstrate the feasibility of the diagnostic scheme, two associated bench simulation experiments were carried out in the laboratory, in which the plasma was simulated by a piece of polytetrafluoroethene plate, and the Faraday rotation effect was simulated by a rotating half-wave plate. Simulation results agreed well with the initial experimental conditions. At present, the HCOOH laser interferometer/polarimeter system is being assembled on HL-2A, and is planned to be applied in the 2014-2015 experimental campaign.
基金the National MCF Energy R&D Program of China(No.2018YFE0310300)National Natural Science Foundation of China(Nos.11905080 and 51821005)。
文摘The J-TEXT three-wave polarimeter-interferometer system(POLARIS),which measures timespace distribution of electron density and current density,has been optimized with both the optical system and the equilibrium reconstruction method.The phase resolution of a Faraday rotation angle has been improved from 0.1 to 0.06 degree in chords from–0.18 to 0.18 m(plasma minor radius),and the sawtooth oscillation behavior has been detected by Faraday rotation angle measurement.By combining the POLARIS measured data and the equilibrium and fitting code(EFIT),an upgraded equilibrium reconstruction method has been developed,which provides a more accurate temporal and spatial distribution of current density and electron density.By means of the optimized POLARIS and improved equilibrium reconstruction,variations of profiles with increasing density have been carried out,under both Ohmic and electron cyclotron resonance heating discharges.
基金supported by the National Key R&D Program of China with No.2021YFA1600404the National Natural Science Foundation of China (NSFC, Grant Nos. 11991051, 11573067, 11673062,11527804, U1931206 and 11873091)+3 种基金the CAS “Light of West China” Programthe Yunnan Province Basic Research Plan with No. 2019FA001the China Manned Space Project with No. CMS-CSST-2021-A06funded by Yunnan Province,Chinese Academy of Sciences and NSFC。
文摘Polarimetry plays an important role in investigating physical properties for celestial objects. We present a polarimeter named YFPOL for the Cassegrain focus of the Lijiang 2.4 m Telescope(LJT) of Yunnan Observatories, Chinese Academy of Sciences. YFPOL is a traditional single-beam polarimeter with a rotating polarizer. As the focal-reducer instrument Yunnan Faint Object Spectrograph and Camera(YFOSC) is always positioned on the Cassegrain focal plane of LJT, we develop two sets of ultra-thin(thickness <12 mm) polarizer rotation control systems with wireless charging and control functions, which are suitable for mounting on the two front-wheels of YFOSC. One set is used as the polarimetric calibration unit, and the other is for the polarimetric modulation unit. Both of the polarizers have an ultra-high contrast ratio of 1,000,000:1 in the optical band. We investigate the instrumental polarization characteristics(IPCs) in the full field of view that is transferred from YFOSC. Furthermore, we identify that the IPCs change when the Cassegrain axis rotates. The spurious polarization from the IPCs can be effectively minimized by flat-fielding using the unpolarized domeflat, when the Cassegrain rotation angle is the same or nearest to that of the polarization observation. We develop a quasiautomatic pipeline for YFPOL and its effectiveness has been verified by tests of the polarimetric observation with blazar S5 0716+714. The calibration is performed by observing the zero-polarized and highly-polarized standard stars. We successfully reach high precision polarization in the 7’ field of view, and the systematic uncertainty is below 0.8% for a V = 11.68 target with a 10 s exposure. The instrument polarization angle offset is 2°. 6. YFPOL is not only a simple polarimeter, but also a spectropolarimeter with grisms that can be considered in the future.
基金supported by Grant-in-Aid for Science Research from the Ministry of Education,Culture,Sports and Technology of Japan
文摘We report the design concept and performance of a compact,lightweight and economical imaging polarimeter,the Triple Range Imager and POLarimeter(TRIPOL),capable of simultaneous optical imagery and polarimetry.TRIPOL splits the beam in wavelengths from 400 to 830 nm into g′-,r′-and i′-bands with two dichroic mirrors,and measures polarization with an achromatic half-waveplate and a wire grid polarizer.The simultaneity makes TRIPOL a useful tool for small telescopes for the photometry and polarimetry of time variable and wavelength dependent phenomena.TRIPOL is designed for a Cassegrain telescope with an aperture of^1 m.This paper presents the engineering considerations of TRIPOL and compares the expected with observed performance.Using the Lulin 1-m telescope and 100 seconds of integration,the limiting magnitudes are g′~19.0 mag,r′~18.5 mag and i′~18.0 mag with a signal-to-noise ratio of 10,in agreement with design expectation.The instrumental polarization is measured to be^0.3%in the three bands.Two applications,one to the star-forming cloud IC 5146 and the other to the young variable GM Cep,are presented as demonstrations.
基金funding support from the National Natural Science Foundation of China(Grant Nos.11633003,12025301 and 11821303)the CAS Strategic Priority Program on Space Science(Grant No.XDA15020501-02)the National Key R&D Project(Grant Nos.2018YFA0404502 and 2016YFA040080X)。
文摘PolarLight is a space-borne X-ray polarimeter that measures the X-ray polarization via electron tracking in an ionization chamber.It is a collimated instrument and thus suffers from the background on the whole detector plane.The majority of background events are induced by high energy charged particles and show ionization morphologies distinct from those produced by X-rays of interest.Comparing on-source and off-source observations,we find that the two datasets display different distributions on image properties.The boundaries between the source and background distributions are obtained and can be used for background discrimination.Such a means can remove over 70%of the background events measured with PolarLight.This approaches the theoretical upper limit of the background fraction that is removable and justifies its effectiveness.For observations with the Crab nebula,the background contamination decreases from 25%to 8%after discrimination,indicative of a polarimetric sensitivity of around 0.2 Crab for PolarLight.This work also provides insights into future X-ray polarimetric telescopes.
基金supported by the NSFC(Grant Nos.11220101001,11433007,11328302,11373005 and 11303064)the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant Nos.XDA04070600 and XDA04075200)+2 种基金the special funding for Young Researchers of Nanjing Institute of Astronomical Optics&Technologythe special fund for astronomy(Grant No.KT2013-022)of CAS.carried out at California State University Northridge,with support from the Mt.Cuba Astronomical Foundation
文摘The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.
基金supported by the National Magnetic Confinement Fusion Program of China(Nos.2012GB101002,2014GB106002,2014GB103000,2013GB10200)National Natural Science Foundation of China(Nos.11105184,11205199 and 11375237)
文摘The method of plasma current profile reconstruction using the polarimeter/interferometer（POINT） data from a simulated equilibrium is explored and validated.It is shown that the safety factor（q） profile can be generally reconstructed from the external magnetic and POINT data.The reconstructed q profile is found to reasonably agree with the initial equilibriums.Comparisons of reconstructed q and density profiles using the magnetic data and the POINT data with 3%,5%and 10%random errors are investigated.The result shows that the POINT data could be used to a reasonably accurate determination of the q profile.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB3903102 and 2022YFB3607700)the National Natural Science Foundation of China(No.62435018)+3 种基金the Innovation Program for Quantum Science and Technology(No.2021ZD0301100)the USTC Research Funds of the Double First-Class Initiative(No.YD2030002023)the Research Cooperation Fund of SAST,CASC(No.SAST2022-075)the Postdoctoral Fellowship Program of CPSF(No.GZC20232559)。
文摘Polarimeter is a vital precision tool used for measuring optical parameters through polarization variations.Among the wide range of application fields,the precise measurement of photosensitive materials is an unavoidable task but faces immense obstacles due to the excessive input photons.Facing this situation,introducing a quantum source into the classical precision measurement system is a feasible way to enhance the detection accuracy under the low illumination regime.In this work,we employ polarization-entangled photon pairs in the classical polarimeter to precisely detect the relative phase retardance of uniform anisotropic media.The experimental results show that the accuracy can reach the nanometer scale at extremely low input intensity,and the stabilities are within 0.4%for all samples.Our work paves the way for polarization measurement at low incident light intensity,with potential applications in measuring photosensitive materials and remote monitoring scenarios.
基金supported by the National Natural Science Foundation of China(Nos.11604227,62175222,and 62105369)the International Visiting Program for Excellent Young Scholars of SCU(No.20181504)+3 种基金the International Science and Technology Innovation Cooperation of Sichuan Province(No.21GJHZ0230)the China Postdoctoral Science Foundation(No.W03019023601004373)the Natural Science Foundation of Hunan Province(No.2025JJ40065)the Basic Research Program of National Major Project of China(No.JG2023273)。
文摘Randomness describes one inherent property of self-assembled metamaterials and greatly limits the practical applications of metamaterials based on bottom-up techniques,such as the microsphere lithography technique.Herein,by subtly utilizing the randomness in long-range disorder metasurfaces,we demonstrate a high-performance one-shot full-Stokes polarimeter in the visible waveband.The long-range disorder metasurfaces,i.e.,chiral shells,were realized by depositing Ag on the self-assembled microsphere monolayer comprised of many micro-domains of random lattice directions and areas.The distinct optical anisotropy and chirality in different micro-domains can result in distinct photo-currents to the photodetector array placed underneath upon the injection of polarized lights.Through establishing the mapping relationship S=f[/]between the detected photo-currents/and the states of polarization(SoP)S with the convolutional neural network(CNN)algorithm,we realize a high-precision full-Stokes polarimeter in the waveband ranging from 500 to 650 nm,and the minimum mean square errors(MSEs)can reach about 0.37%(S_(1)),0.33%(S_(2)),and 0.19%(S_(3))at 566 nm.The average MSEs in the investigated waveband are 0.49%(S_(1)),0.45%(S_(2)),and 0.31%(S_(3)),respectively.We have systematically investigated the macro-and micro-optical properties of chiral shells,the optical randomness of chiral shells in different domains,the reference SoP number,the exposure time and pixel number of the CCD,as well as the reliability and stability of the system.
