Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes.In this paper,the state of art control methods—proportional integral(PI)control,linear quadratic...Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes.In this paper,the state of art control methods—proportional integral(PI)control,linear quadratic Gaussian(LQG)control,disturbance feed forward(DFF)control,and disturbance observer control(DOBC)of Tip-Tilt mirror to reject vibrations are first reviewed,and then compared systematically and comprehensively.Some mathematical transformations allow PI,LQG,DFF,and DOBC to be described in a uniform framework of sensitivity function that expresses their advantages and disadvantages.In essence,feed forward control based-inverse model is the main idea of current techniques,which is dependent on accuracies of models in terms of Tip-Tilt mirror and vibrations.DOBC can relax dependences on accuracy model,and therefore this survey concentrates on concise tutorials of this method with clear descriptions of their features in the control area of disturbance rejections.Its applications in various conditions are reviewed with emphasis on the effectiveness.Finally,the open problems,challenges and research prospects of DOBC of Tip-Tilt mirror are discussed.展开更多
Both long-term environmental durability and high reflectance of protected-Al mirrors are of great importance for developing the optical instruments in the vacuum ultraviolet(VUV) applications. In this paper, the depen...Both long-term environmental durability and high reflectance of protected-Al mirrors are of great importance for developing the optical instruments in the vacuum ultraviolet(VUV) applications. In this paper, the dependence of spectral property and environmental durability of MgF2 over-coated Al mirrors using a 3-step method on deposition temperature of the outermost MgF2 layer are investigated in detail. Optics(reflectance), structure(surface morphology and crystalline), and environmental durability(humidity test) are characterized and discussed. The results show that both optical and moistureresistant properties of MgF2 over-coated Al mirrors are dependent on MgF2 deposition temperature, and the optimal deposition temperature for the outermost MgF2 layer should be between 250℃ and 300℃ for MgF2 over-coated Al mirrors to have both reasonably high reflectance in the VUV spectral range and high moisture resistance for long lifetime applications.展开更多
In this paper,we propose a new visual tracking method in light of salience information and deep learning.Salience detection is used to exploit features with salient information of the image.Complicated representations...In this paper,we propose a new visual tracking method in light of salience information and deep learning.Salience detection is used to exploit features with salient information of the image.Complicated representations of image features can be gained by the function of every layer in convolution neural network(CNN).The characteristic of biology vision in attention-based salience is similar to the neuroscience features of convolution neural network.This motivates us to improve the representation ability of CNN with functions of salience detection.We adopt the fully-convolution networks(FCNs)to perform salience detection.We take parts of the network structure to perform salience extraction,which promotes the classification ability of the model.The network we propose shows great performance in tracking with the salient information.Compared with other excellent algorithms,our algorithm can track the target better in the open tracking datasets.We realize the 0.5592 accuracy on visual object tracking 2015(VOT15)dataset.For unmanned aerial vehicle 123(UAV123)dataset,the precision and success rate of our tracker is 0.710 and 0.429.展开更多
An optical transfer function （OTF） reconstruction model is first embedded into incoherent Fourier ptychography （IFP）. The leading result is a proposed algorithm that can recover both the super-resolution image and...An optical transfer function （OTF） reconstruction model is first embedded into incoherent Fourier ptychography （IFP）. The leading result is a proposed algorithm that can recover both the super-resolution image and the OTF of an imaging system with unknown aberrations simultaneously. This model overcomes the difficult problem of OTF estimation that the previous IFP faces. The effectiveness of this algorithm is demonstrated by numerical simulations, and the superior reconstruction is presented. We believe that the reported algorithm can extend the original IFP for more complex conditions and may provide a solution by using structured light for characterization of optical systems＇ aberrations.展开更多
Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. I...Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum＋weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.展开更多
This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis in...This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis instead of a single motor drive, which is usually used in a classical design. This new configuration and mechanism can reduce the motor to half the size used in the former design, and it also provides some other advantages. A master-slave current control mode is employed to synchronize the two motors. Acceleration feedback control is utilized to further enhance the servo performance. Extensive experiments are used to validate the effectiveness of the proposed control algorithm in synchronization, disturbance attenuation and low-velocity tracking.展开更多
In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperatur...In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.展开更多
Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance（MR） of p-type diamond films, a revised model of valence band split-off over tempera...Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance（MR） of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films （Corbino discs）. It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.展开更多
Extended state observer(ESO)is heavily limited by the unknown disturbance and its derivative,which requires high observing gains to decrease estimating error,resulting in serious noise sensitivity.To modify the distur...Extended state observer(ESO)is heavily limited by the unknown disturbance and its derivative,which requires high observing gains to decrease estimating error,resulting in serious noise sensitivity.To modify the disturbance estimation characteristics encountered by the observer,the active compression extended state observer(ACESO)is proposed in this study.The ACESO decreases the bound of residual lumped disturbance and its derivative by actively compressing the initial lumped disturbance,without relying on prior knowledge.The stability constraint and convergence results of ACESO are analyzed and compared with ESO theoretically.The results show that the ACESO mitigates the trade-off between noise sensitivity and high-gain observation.Benefiting from active compression,the ACESO has substantially less noise sensitivity than the ESO,while obtaining the same and even better estimating performance than the ESO.In addition,the nonlinear ACESO is discussed,which automatically balances the contradiction between estimation and convergence.Simulations and experiments demonstrate the effectiveness of the proposed methods.展开更多
Abstract In this paper, a cascade acceleration feedback control （AFC） enhanced by a disturbance observa- tion and compensation （DOC） method is proposed to improve the tracking precision of telescope systems. Teles...Abstract In this paper, a cascade acceleration feedback control （AFC） enhanced by a disturbance observa- tion and compensation （DOC） method is proposed to improve the tracking precision of telescope systems. Telescope systems usually suffer some uncertain disturbances, such as wind load, nonlinear friction and other unknown disturbances. To ensure tracking precision, an acceleration feedback loop which can in- crease the stiffness of such a system is introduced. Moreover, to further improve the tracking precision, we introduce the DOC method which can accurately estimate the disturbance and compensate it. Furthermore, the analysis of tracking accuracy used by this method is proposed. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of a telescope system.展开更多
Phase modulation is first introduced into aperture-scanning Four/er ptychography. A series of images are acquired with an aperture scanning the Fourier plane of an optical system with a phase modulator. Then the repor...Phase modulation is first introduced into aperture-scanning Four/er ptychography. A series of images are acquired with an aperture scanning the Fourier plane of an optical system with a phase modulator. Then the reported algorithm synthesizes the captured images in the frequency domain to recover a high-resolution complex object wavefront. The leading results are considerably improved in robustness against the noises and shift errors, with a much faster convergence speed compared with the conventional scheme without phase modulation.展开更多
Electro-optical tracking systems have been widely used in the cutting-edge domains of free space environment detection and communication owing to their exceptional performance.However,external disturbances often signi...Electro-optical tracking systems have been widely used in the cutting-edge domains of free space environment detection and communication owing to their exceptional performance.However,external disturbances often significantly impact the working accuracy of these systems.As their scope of application continues to broaden,increasingly complex operating conditions introduce more intricate environments and disturbances.This paper introduces a composite control structure of an enhanced error-based observer,rooted in the repetitive control strategy,tailored for two types of complex disturbances:periodic harmonic disturbance and narrow-band peak periodic disturbance.This structure not only ensures the system's stability,but also suppresses periodic disturbances across multiple frequencies,effectively addressing the challenge that current disturbance suppression methods face in mitigating complex periodic disturbances.Moreover,necessary proofs are provided and an experimental platform is established for the electro-optical system,demonstrating the efficacy and reliability of the proposed control methods under various conditions.展开更多
Non-line-of-sight(NLOS)imaging has potential in autonomous driving,robotic vision,and medical imaging,but it is hindered by extensive scans.In this work,we provide a time-multiplexing NLOS imaging scheme that is desig...Non-line-of-sight(NLOS)imaging has potential in autonomous driving,robotic vision,and medical imaging,but it is hindered by extensive scans.In this work,we provide a time-multiplexing NLOS imaging scheme that is designed to reduce the number of scans on the relay surface.The approach introduces a time delay at the transmitting end,allowing two laser pulses with different delays to be sent per period and enabling simultaneous acquisition of data from multiple sampling points.Additionally,proof-of-concept experiments validate the feasibility of this approach,achieving reconstruction with half the scans.These results demonstrate a promising strategy for real-time NLOS imaging.展开更多
This paper presents a polarization descattering imaging method for underwater detection in which the targets have nonuniform polarization characteristics. The core of this method takes the nonuniform distribution of t...This paper presents a polarization descattering imaging method for underwater detection in which the targets have nonuniform polarization characteristics. The core of this method takes the nonuniform distribution of the polarization information of the target-reflected light into account and expands the application field of underwater polarization imaging.Independent component analysis was used to separate the target light and backscattered light. Theoretical analysis and proof-of-concept experiments were employed to demonstrate the effectiveness of the proposed method in estimating target information. The proposed method showed superiority in accurately estimating the target information compared with other polarization imaging methods.展开更多
In this Letter,we report a Golay3 sparse-aperture telescope newly built in the Key Laboratory of Optical Engineering,Chinese Academy of Sciences and present the experimental results of enhanced resolution.The telescop...In this Letter,we report a Golay3 sparse-aperture telescope newly built in the Key Laboratory of Optical Engineering,Chinese Academy of Sciences and present the experimental results of enhanced resolution.The telescope consisting of 3 collector telescopes of 127 mm diameter can achieve a theoretical resolution corresponding to a monolithic aperture of 245 mm diameter.It is shown by the experimental results that the resolution is improved to 3.33μrad with respect to the diffraction limit of 6.07μrad for a single aperture using the Rayleigh criteria at 632 nm.The compact optical configuration and cophasing approach are also described.展开更多
Polarization underwater imaging is of great potential to target detection in turbid water. Typical methods are challenged by the requirement on degrees of polarization(Do Ps) of both target light and backscattering. A...Polarization underwater imaging is of great potential to target detection in turbid water. Typical methods are challenged by the requirement on degrees of polarization(Do Ps) of both target light and backscattering. A polarization descattering imaging method was developed using the Mueller matrix, which in turn derived a depolarization(Dep) index from the Mueller matrix to characterize scattering media by estimating the transmittance map by combining a developed optimal function.By quantifying light attenuation with the transmittance map, a clear vision of targets can be recovered. Only using the information of scattering media, the underwater vision under diverse water turbidity was enhanced by the results of experimental data.展开更多
Highly efficient stacked organic light-emitting devices (OLEDs) have been fabricated using Mg:Alq3:BCP/ WO3 as a novel intermediate layer, which connects two identical emissive units. The stacked OLEDs consisting of N...Highly efficient stacked organic light-emitting devices (OLEDs) have been fabricated using Mg:Alq3:BCP/ WO3 as a novel intermediate layer, which connects two identical emissive units. The stacked OLEDs consisting of NPB/Alq3 exhibited high current efficiency and brightness characteristics over conven- tional single-unit device. At 200 mA/cm2, the current efficiency of the stacked OLEDs using the inter- mediate layers of Mg:Alq3:BCP/WO3 were about 6.85 cd/A, doubling that of the conventional device. The results may prove the method to be effective to enhance the current efficiency and brightness of OLEDs.展开更多
Flat optics has been considered promising for constructions of spaceborne imaging systems with apertures in excess of 10 m.Despite recent advances,there are long-existing challenges to perform in-phase stitching of mu...Flat optics has been considered promising for constructions of spaceborne imaging systems with apertures in excess of 10 m.Despite recent advances,there are long-existing challenges to perform in-phase stitching of multiple flat optical elements.Phasing the segmented planar instrument has remained at the proof of concept.Here,we achieve autonomous system-level cophasing of a 1.5-m stitching flat device,bridging the gap between the concept and engineering implementation.To do so,we propose a flat element stitching scheme,by manipulating the point spread function,which enables our demonstration of automatically bringing seven flat segments'tip/tilt and piston errors within the tolerance.With phasing done,the 1.5-m system has become the largest phased planar instrument ever built in the world,to our knowledge.The first demonstration of phasing the large practical flat imaging system marks a significant step towards fielding a 10-m class one in space,also paving the way for ultrathin flat imaging in various remote applications.展开更多
A high power and good beam quality InGaAs/GaAs quantum well semiconductor disk laser at 1 015 nm wavelength is reported. The semiconductor wafer is grown in reverse order： substrate is on the window side and the dist...A high power and good beam quality InGaAs/GaAs quantum well semiconductor disk laser at 1 015 nm wavelength is reported. The semiconductor wafer is grown in reverse order： substrate is on the window side and the distributed Bragg reflector is the last grown epilayer. Then the wafer is up-side-down and capillary bonded to a SiC heatsink, and the substrate is chemically etched. Because the total thickness of the substrate-removed structure is less than 10 #m, the thermal management of the laser is significantly improved, and the maximum output power over 0.6 W is obtained using a 3% output coupler and 3.2 W incident pump power. The M2 factors of 1.02 and 1.01 indicate a near-diffraction-limited beam quality. To further reveal the characteristics of this substrate-etched structure on the thermal management, the heat flux and the temperature distribution of the gain wafer are numerically analyzed, and the corresponding results are discussed.展开更多
文摘Structural vibrations in Tip-Tilt modes usually affect the closed-loop performance of astronomically optical telescopes.In this paper,the state of art control methods—proportional integral(PI)control,linear quadratic Gaussian(LQG)control,disturbance feed forward(DFF)control,and disturbance observer control(DOBC)of Tip-Tilt mirror to reject vibrations are first reviewed,and then compared systematically and comprehensively.Some mathematical transformations allow PI,LQG,DFF,and DOBC to be described in a uniform framework of sensitivity function that expresses their advantages and disadvantages.In essence,feed forward control based-inverse model is the main idea of current techniques,which is dependent on accuracies of models in terms of Tip-Tilt mirror and vibrations.DOBC can relax dependences on accuracy model,and therefore this survey concentrates on concise tutorials of this method with clear descriptions of their features in the control area of disturbance rejections.Its applications in various conditions are reviewed with emphasis on the effectiveness.Finally,the open problems,challenges and research prospects of DOBC of Tip-Tilt mirror are discussed.
基金Project supported by the West Light Foundation of the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant No.61805247)
文摘Both long-term environmental durability and high reflectance of protected-Al mirrors are of great importance for developing the optical instruments in the vacuum ultraviolet(VUV) applications. In this paper, the dependence of spectral property and environmental durability of MgF2 over-coated Al mirrors using a 3-step method on deposition temperature of the outermost MgF2 layer are investigated in detail. Optics(reflectance), structure(surface morphology and crystalline), and environmental durability(humidity test) are characterized and discussed. The results show that both optical and moistureresistant properties of MgF2 over-coated Al mirrors are dependent on MgF2 deposition temperature, and the optimal deposition temperature for the outermost MgF2 layer should be between 250℃ and 300℃ for MgF2 over-coated Al mirrors to have both reasonably high reflectance in the VUV spectral range and high moisture resistance for long lifetime applications.
文摘In this paper,we propose a new visual tracking method in light of salience information and deep learning.Salience detection is used to exploit features with salient information of the image.Complicated representations of image features can be gained by the function of every layer in convolution neural network(CNN).The characteristic of biology vision in attention-based salience is similar to the neuroscience features of convolution neural network.This motivates us to improve the representation ability of CNN with functions of salience detection.We adopt the fully-convolution networks(FCNs)to perform salience detection.We take parts of the network structure to perform salience extraction,which promotes the classification ability of the model.The network we propose shows great performance in tracking with the salient information.Compared with other excellent algorithms,our algorithm can track the target better in the open tracking datasets.We realize the 0.5592 accuracy on visual object tracking 2015(VOT15)dataset.For unmanned aerial vehicle 123(UAV123)dataset,the precision and success rate of our tracker is 0.710 and 0.429.
基金Supported by the National Natural Science Foundation of China under Grant No 61205144the Research Project of National University of Defense Technology under Grant No JC13-07-01the Key Laboratory of High Power Laser and Physics of Chinese Academy of Sciences
文摘An optical transfer function （OTF） reconstruction model is first embedded into incoherent Fourier ptychography （IFP）. The leading result is a proposed algorithm that can recover both the super-resolution image and the OTF of an imaging system with unknown aberrations simultaneously. This model overcomes the difficult problem of OTF estimation that the previous IFP faces. The effectiveness of this algorithm is demonstrated by numerical simulations, and the superior reconstruction is presented. We believe that the reported algorithm can extend the original IFP for more complex conditions and may provide a solution by using structured light for characterization of optical systems＇ aberrations.
基金Supported by China Manned Space Program,Technology and Engineering Center for Space Utilization Chinese Academy of Sciences,Chinese Academy of Sciencesthe National Natural Science Foundation of China
文摘Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum＋weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.
文摘This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis instead of a single motor drive, which is usually used in a classical design. This new configuration and mechanism can reduce the motor to half the size used in the former design, and it also provides some other advantages. A master-slave current control mode is employed to synchronize the two motors. Acceleration feedback control is utilized to further enhance the servo performance. Extensive experiments are used to validate the effectiveness of the proposed control algorithm in synchronization, disturbance attenuation and low-velocity tracking.
基金supported by the National Natural Science Foundation of China(No.62271109)。
文摘In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.
基金Project supported by the Chongqing City Education Commission of China (Grant No. 040804)
文摘Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance（MR） of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films （Corbino discs）. It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.
基金supported by the Special Research Assistant Program,Chinese Academy of Sciences,China(E329691C21)Sichuan Science and Technology Program,China(2024NSFSC1481)National Natural Science Foundation of China(92471204,62271109).
文摘Extended state observer(ESO)is heavily limited by the unknown disturbance and its derivative,which requires high observing gains to decrease estimating error,resulting in serious noise sensitivity.To modify the disturbance estimation characteristics encountered by the observer,the active compression extended state observer(ACESO)is proposed in this study.The ACESO decreases the bound of residual lumped disturbance and its derivative by actively compressing the initial lumped disturbance,without relying on prior knowledge.The stability constraint and convergence results of ACESO are analyzed and compared with ESO theoretically.The results show that the ACESO mitigates the trade-off between noise sensitivity and high-gain observation.Benefiting from active compression,the ACESO has substantially less noise sensitivity than the ESO,while obtaining the same and even better estimating performance than the ESO.In addition,the nonlinear ACESO is discussed,which automatically balances the contradiction between estimation and convergence.Simulations and experiments demonstrate the effectiveness of the proposed methods.
基金supported by the Quantum Communication Project,one of the Strategic Pilot Projects,Chinese Academy of Sciences
文摘Abstract In this paper, a cascade acceleration feedback control （AFC） enhanced by a disturbance observa- tion and compensation （DOC） method is proposed to improve the tracking precision of telescope systems. Telescope systems usually suffer some uncertain disturbances, such as wind load, nonlinear friction and other unknown disturbances. To ensure tracking precision, an acceleration feedback loop which can in- crease the stiffness of such a system is introduced. Moreover, to further improve the tracking precision, we introduce the DOC method which can accurately estimate the disturbance and compensate it. Furthermore, the analysis of tracking accuracy used by this method is proposed. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of a telescope system.
基金Supported by the National Natural Science Foundation of China under Grant No 61205144the Research Project of National University of Defense Technology under Grant No JC13-07-01the key Laboratory of High Power Laser and Physics of Chinese Academy of Sciences
文摘Phase modulation is first introduced into aperture-scanning Four/er ptychography. A series of images are acquired with an aperture scanning the Fourier plane of an optical system with a phase modulator. Then the reported algorithm synthesizes the captured images in the frequency domain to recover a high-resolution complex object wavefront. The leading results are considerably improved in robustness against the noises and shift errors, with a much faster convergence speed compared with the conventional scheme without phase modulation.
文摘Electro-optical tracking systems have been widely used in the cutting-edge domains of free space environment detection and communication owing to their exceptional performance.However,external disturbances often significantly impact the working accuracy of these systems.As their scope of application continues to broaden,increasingly complex operating conditions introduce more intricate environments and disturbances.This paper introduces a composite control structure of an enhanced error-based observer,rooted in the repetitive control strategy,tailored for two types of complex disturbances:periodic harmonic disturbance and narrow-band peak periodic disturbance.This structure not only ensures the system's stability,but also suppresses periodic disturbances across multiple frequencies,effectively addressing the challenge that current disturbance suppression methods face in mitigating complex periodic disturbances.Moreover,necessary proofs are provided and an experimental platform is established for the electro-optical system,demonstrating the efficacy and reliability of the proposed control methods under various conditions.
基金supported by the National Natural Science Foundation of China(No.62271468)。
文摘Non-line-of-sight(NLOS)imaging has potential in autonomous driving,robotic vision,and medical imaging,but it is hindered by extensive scans.In this work,we provide a time-multiplexing NLOS imaging scheme that is designed to reduce the number of scans on the relay surface.The approach introduces a time delay at the transmitting end,allowing two laser pulses with different delays to be sent per period and enabling simultaneous acquisition of data from multiple sampling points.Additionally,proof-of-concept experiments validate the feasibility of this approach,achieving reconstruction with half the scans.These results demonstrate a promising strategy for real-time NLOS imaging.
基金This work was supported by the Key Laboratory of Optical Engineering,Chinese Academy of Sciences(No.QC20191097)the National Natural Science Foundation of China(NSFC)(Nos.62075175 and 62005203).
文摘This paper presents a polarization descattering imaging method for underwater detection in which the targets have nonuniform polarization characteristics. The core of this method takes the nonuniform distribution of the polarization information of the target-reflected light into account and expands the application field of underwater polarization imaging.Independent component analysis was used to separate the target light and backscattered light. Theoretical analysis and proof-of-concept experiments were employed to demonstrate the effectiveness of the proposed method in estimating target information. The proposed method showed superiority in accurately estimating the target information compared with other polarization imaging methods.
基金supported by the National Natural Science Foundation of China(No.61205144)the Research Project of National University of Defense Technology(No.JC13-07-01)the Key Laboratory of High Power Laser and Physics,CAS
文摘In this Letter,we report a Golay3 sparse-aperture telescope newly built in the Key Laboratory of Optical Engineering,Chinese Academy of Sciences and present the experimental results of enhanced resolution.The telescope consisting of 3 collector telescopes of 127 mm diameter can achieve a theoretical resolution corresponding to a monolithic aperture of 245 mm diameter.It is shown by the experimental results that the resolution is improved to 3.33μrad with respect to the diffraction limit of 6.07μrad for a single aperture using the Rayleigh criteria at 632 nm.The compact optical configuration and cophasing approach are also described.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Nos.62075175 and 62005203)the Key Laboratory of Optical Engineering,Chinese Academy of Sciences。
文摘Polarization underwater imaging is of great potential to target detection in turbid water. Typical methods are challenged by the requirement on degrees of polarization(Do Ps) of both target light and backscattering. A polarization descattering imaging method was developed using the Mueller matrix, which in turn derived a depolarization(Dep) index from the Mueller matrix to characterize scattering media by estimating the transmittance map by combining a developed optimal function.By quantifying light attenuation with the transmittance map, a clear vision of targets can be recovered. Only using the information of scattering media, the underwater vision under diverse water turbidity was enhanced by the results of experimental data.
基金Supported by the National Natural Science Foundation of China (Grant No. 60806047)Research Programs for Science and Technology of Chongqing Municipal Education Commission (Grant No. KJ080816)Natural Science Foundation of Chongqing Normal University (Grant No. 07XLB015)
文摘Highly efficient stacked organic light-emitting devices (OLEDs) have been fabricated using Mg:Alq3:BCP/ WO3 as a novel intermediate layer, which connects two identical emissive units. The stacked OLEDs consisting of NPB/Alq3 exhibited high current efficiency and brightness characteristics over conven- tional single-unit device. At 200 mA/cm2, the current efficiency of the stacked OLEDs using the inter- mediate layers of Mg:Alq3:BCP/WO3 were about 6.85 cd/A, doubling that of the conventional device. The results may prove the method to be effective to enhance the current efficiency and brightness of OLEDs.
基金National Key Research and Development Program of China (2022YFB3901900)National Natural Science Foundation of China (62005289)+1 种基金Youth Innovation Promotion Association (2020372)Outstanding Scientist Project of Tianfu Qingcheng Program。
文摘Flat optics has been considered promising for constructions of spaceborne imaging systems with apertures in excess of 10 m.Despite recent advances,there are long-existing challenges to perform in-phase stitching of multiple flat optical elements.Phasing the segmented planar instrument has remained at the proof of concept.Here,we achieve autonomous system-level cophasing of a 1.5-m stitching flat device,bridging the gap between the concept and engineering implementation.To do so,we propose a flat element stitching scheme,by manipulating the point spread function,which enables our demonstration of automatically bringing seven flat segments'tip/tilt and piston errors within the tolerance.With phasing done,the 1.5-m system has become the largest phased planar instrument ever built in the world,to our knowledge.The first demonstration of phasing the large practical flat imaging system marks a significant step towards fielding a 10-m class one in space,also paving the way for ultrathin flat imaging in various remote applications.
文摘A high power and good beam quality InGaAs/GaAs quantum well semiconductor disk laser at 1 015 nm wavelength is reported. The semiconductor wafer is grown in reverse order： substrate is on the window side and the distributed Bragg reflector is the last grown epilayer. Then the wafer is up-side-down and capillary bonded to a SiC heatsink, and the substrate is chemically etched. Because the total thickness of the substrate-removed structure is less than 10 #m, the thermal management of the laser is significantly improved, and the maximum output power over 0.6 W is obtained using a 3% output coupler and 3.2 W incident pump power. The M2 factors of 1.02 and 1.01 indicate a near-diffraction-limited beam quality. To further reveal the characteristics of this substrate-etched structure on the thermal management, the heat flux and the temperature distribution of the gain wafer are numerically analyzed, and the corresponding results are discussed.
