The phase diversity wavefront sensor is one of the tools used to estimate wavefront aberration, and it is often used as a wavefront sensor in adaptive optics systems. However, the performance of the traditional phase ...The phase diversity wavefront sensor is one of the tools used to estimate wavefront aberration, and it is often used as a wavefront sensor in adaptive optics systems. However, the performance of the traditional phase diversity wavefront sensor is limited by the accuracy and dynamic ranges of the intensity distribution at the focus and defocus positions of the CCD camera. In this paper, a modified phase diversity wavefront sensor based on a diffraction grating is proposed to improve the ability to measure the wavefront aberration with larger amplitude and higher spatial frequency. The basic principle and the optics construction of the proposed method are also described in detail. The noise propagation property of the proposed method is also analysed by using the numerical simulation method, and comparison between the diffraction grating phase diversity wavefront sensor and the traditional phase diversity wavefront sensor is also made. The simulation results show that the diffraction grating phase diversity wavefront sensor can obviously improve the ability to measure the wavefront aberration, especially the wavefront aberration with larger amplitude and higher spatial frequency.展开更多
A simple method to objectively and simultaneously measure eye's longitudinal and transverse chromatic aberrations was proposed.A dual-wavelength wavefront measurement system using two Hartmann-Shack wavefront sens...A simple method to objectively and simultaneously measure eye's longitudinal and transverse chromatic aberrations was proposed.A dual-wavelength wavefront measurement system using two Hartmann-Shack wavefront sensors was developed.The wavefronts of the red(639.1 nm)and near-infrared(786.0 nm)lights were measured simultaneously for different positions in the model eye.The chromatic wavefronts were converted into Zernike polynomials.The Zernike tilt cofficient(irst term)was used to calculate the transverse chromatic aberration along the ax-direction,while the Zernike defocus coefficient(fourth term)was used to calculate the longi-tudinal chromatic aberration.The measurement and simulation data were consistent.展开更多
High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device（EMCCD） applied in the Shack–Hartmann wavefront sensor（S–H WFS） in adaptive optics（AO）.However,when the brightness ...High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device（EMCCD） applied in the Shack–Hartmann wavefront sensor（S–H WFS） in adaptive optics（AO）.However,when the brightness of the target changes in a large scale,the fixed electron multiplying（EM） gain will not be suited to the sensing limitation.Therefore an auto-gain-control method based on the brightness of light-spots array in S–H WFS is proposed in this paper.The control value is the average of the maximum signals of every light spot in an array,which has been demonstrated to be kept stable even under the influence of some noise and turbulence,and sensitive enough to the change of target brightness.A goal value is needed in the control process and it is predetermined based on the characters of EMCCD.Simulations and experiments have demonstrated that this auto-gain-control method is valid and robust,the sensing SNR reaches the maximum for the corresponding signal level,and especially is greatly improved for those dim targets from 6 to 4 magnitude in the visual band.展开更多
Our adaptive optics system based on a non-modulation pyramid wavefront sensor is integrated into a 1.8 m astronomical telescope installed at the Yunnan Observatory in LiJiang, and the first light with high-resolution ...Our adaptive optics system based on a non-modulation pyramid wavefront sensor is integrated into a 1.8 m astronomical telescope installed at the Yunnan Observatory in LiJiang, and the first light with high-resolution imaging of an astronomical star is successfully achieved. In this Letter, the structure and performance of this system are introduced briefly, and then the observation results of star imaging are reported to show that the angular resolution of an adaptive optics system using a non-modulation pyramid wavefront sensor can approach the diffraction limit quality of a 1.8 m telescope.展开更多
Adaptive optics systems are used to compensate for wavefront distortions introduced by atmospheric turbulence.The distortions are corrected by an adaptable device,normally a deformable mirror.The control signal of the...Adaptive optics systems are used to compensate for wavefront distortions introduced by atmospheric turbulence.The distortions are corrected by an adaptable device,normally a deformable mirror.The control signal of the mirror is based on the measurement delivered by a wavefront sensor.Relevant characteristics of the wavefront sensor are the measurement accuracy,the achievable measurement speed and the robustness against scintillation.The modal holographic wavefront sensor can theoretically provide the highest bandwidth compared to other state of the art wavefront sensors and it is robust against scintillation effects.However,the measurement accuracy suffers from crosstalk effects between different aberration modes that are present in the wavefront.In this paper we evaluate whether the sensor can be used effectively in a closed-loop AO system under realistic turbulence conditions.We simulate realistic optical turbulence represented by more than 2500 aberration modes and take different signal-to-noise ratios into account.We determine the performance of a closed-loop AO system based on the holographic sensor.To counter the crosstalk effects,careful choice of the key design parameters of the sensor is necessary.Therefore,we apply an optimization method to find the best sensor design for maximizing the measurement accuracy.By modifying this method to take the changing effective turbulence conditions during closed-loop operation into account,we can improve the performance of the system,especially for demanding signal-to-noise-ratios,even more.Finally,we propose to implement multiple holographic wavefront sensors without the use of additional hardware,to perform multiple measurement at the same time.We show that the measurement accuracy of the sensor and with this the wavefront flatness can be increased significantly without reducing the bandwidth of the adaptive optics system.展开更多
In order to detect the aberration from a wide field of view（FOV） on the retina with adaptive optics, we present a multiple-object Shack-Hartmann wavefront sensor（MOSHWFS） design. The simulated results indicate tha...In order to detect the aberration from a wide field of view（FOV） on the retina with adaptive optics, we present a multiple-object Shack-Hartmann wavefront sensor（MOSHWFS） design. The simulated results indicate that the wavefront from our MOSHWFS can be reconstructed for multiple objects, and the measurement error can be less than λ∕7 with an MOSHWFS with an FOV of 6.7°, for maximum eye aberration. The experimental result with two objects indicates that the measurement error can be less than λ∕14, with the root mean square of the reference wavefront as 0.798λ and 0.895λ, respectively.展开更多
A numerical simulation model of plenoptic sensor aberration wavefront detection is established to simulate and analyze the detection performance of plenoptic sensor aberration wavefront for different turbulence intens...A numerical simulation model of plenoptic sensor aberration wavefront detection is established to simulate and analyze the detection performance of plenoptic sensor aberration wavefront for different turbulence intensities.The results show that the plenoptic sensor can achieve better distortion wavefront detection,and its wavefront detection accuracy improves with turbulence intensity.The unique optical structure design of the plenoptic sensor makes it more suitable for aberration wavefront detection in strong turbulent conditions.The wavefront detection performance of the plenoptic sensor is not only related to its wavefront reconstruction algorithm but also closely related to its structural parameter settings.The influence of structural parameters on the wavefront detection accuracy of plenoptic sensors under different turbulence intensities is simulated and analyzed.The variation law of wavefront detection accuracy and structural parameters under different turbulence intensities is summarized to provide a reference for the structural design and parameter optimization of plenoptic sensors.展开更多
文摘The phase diversity wavefront sensor is one of the tools used to estimate wavefront aberration, and it is often used as a wavefront sensor in adaptive optics systems. However, the performance of the traditional phase diversity wavefront sensor is limited by the accuracy and dynamic ranges of the intensity distribution at the focus and defocus positions of the CCD camera. In this paper, a modified phase diversity wavefront sensor based on a diffraction grating is proposed to improve the ability to measure the wavefront aberration with larger amplitude and higher spatial frequency. The basic principle and the optics construction of the proposed method are also described in detail. The noise propagation property of the proposed method is also analysed by using the numerical simulation method, and comparison between the diffraction grating phase diversity wavefront sensor and the traditional phase diversity wavefront sensor is also made. The simulation results show that the diffraction grating phase diversity wavefront sensor can obviously improve the ability to measure the wavefront aberration, especially the wavefront aberration with larger amplitude and higher spatial frequency.
基金National Science Foundation of China(NSFC)(61378064)the National High Technology Research and Development Program of China(2015AA020510).
文摘A simple method to objectively and simultaneously measure eye's longitudinal and transverse chromatic aberrations was proposed.A dual-wavelength wavefront measurement system using two Hartmann-Shack wavefront sensors was developed.The wavefronts of the red(639.1 nm)and near-infrared(786.0 nm)lights were measured simultaneously for different positions in the model eye.The chromatic wavefronts were converted into Zernike polynomials.The Zernike tilt cofficient(irst term)was used to calculate the transverse chromatic aberration along the ax-direction,while the Zernike defocus coefficient(fourth term)was used to calculate the longi-tudinal chromatic aberration.The measurement and simulation data were consistent.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174274,61205021,and 61405194)the State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences
文摘High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device（EMCCD） applied in the Shack–Hartmann wavefront sensor（S–H WFS） in adaptive optics（AO）.However,when the brightness of the target changes in a large scale,the fixed electron multiplying（EM） gain will not be suited to the sensing limitation.Therefore an auto-gain-control method based on the brightness of light-spots array in S–H WFS is proposed in this paper.The control value is the average of the maximum signals of every light spot in an array,which has been demonstrated to be kept stable even under the influence of some noise and turbulence,and sensitive enough to the change of target brightness.A goal value is needed in the control process and it is predetermined based on the characters of EMCCD.Simulations and experiments have demonstrated that this auto-gain-control method is valid and robust,the sensing SNR reaches the maximum for the corresponding signal level,and especially is greatly improved for those dim targets from 6 to 4 magnitude in the visual band.
基金supported by the National Natural Science Foundation of China under Grant No.61008038
文摘Our adaptive optics system based on a non-modulation pyramid wavefront sensor is integrated into a 1.8 m astronomical telescope installed at the Yunnan Observatory in LiJiang, and the first light with high-resolution imaging of an astronomical star is successfully achieved. In this Letter, the structure and performance of this system are introduced briefly, and then the observation results of star imaging are reported to show that the angular resolution of an adaptive optics system using a non-modulation pyramid wavefront sensor can approach the diffraction limit quality of a 1.8 m telescope.
基金This work was sponsored by WTD 91(Technical Center of Weapons and Ammunition)of the Federal Defence Forces of Germany-Bundeswehr in the project ABU-SLSby the Office of Naval Research Global under award no.N62909-17-1-2037.
文摘Adaptive optics systems are used to compensate for wavefront distortions introduced by atmospheric turbulence.The distortions are corrected by an adaptable device,normally a deformable mirror.The control signal of the mirror is based on the measurement delivered by a wavefront sensor.Relevant characteristics of the wavefront sensor are the measurement accuracy,the achievable measurement speed and the robustness against scintillation.The modal holographic wavefront sensor can theoretically provide the highest bandwidth compared to other state of the art wavefront sensors and it is robust against scintillation effects.However,the measurement accuracy suffers from crosstalk effects between different aberration modes that are present in the wavefront.In this paper we evaluate whether the sensor can be used effectively in a closed-loop AO system under realistic turbulence conditions.We simulate realistic optical turbulence represented by more than 2500 aberration modes and take different signal-to-noise ratios into account.We determine the performance of a closed-loop AO system based on the holographic sensor.To counter the crosstalk effects,careful choice of the key design parameters of the sensor is necessary.Therefore,we apply an optimization method to find the best sensor design for maximizing the measurement accuracy.By modifying this method to take the changing effective turbulence conditions during closed-loop operation into account,we can improve the performance of the system,especially for demanding signal-to-noise-ratios,even more.Finally,we propose to implement multiple holographic wavefront sensors without the use of additional hardware,to perform multiple measurement at the same time.We show that the measurement accuracy of the sensor and with this the wavefront flatness can be increased significantly without reducing the bandwidth of the adaptive optics system.
基金supported by the National Natural Science Foundation of China(Nos.11174274,11174279,61205021,11204299,61475152,and 61405194)the State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences
文摘In order to detect the aberration from a wide field of view（FOV） on the retina with adaptive optics, we present a multiple-object Shack-Hartmann wavefront sensor（MOSHWFS） design. The simulated results indicate that the wavefront from our MOSHWFS can be reconstructed for multiple objects, and the measurement error can be less than λ∕7 with an MOSHWFS with an FOV of 6.7°, for maximum eye aberration. The experimental result with two objects indicates that the measurement error can be less than λ∕14, with the root mean square of the reference wavefront as 0.798λ and 0.895λ, respectively.
基金the National Natural Science Foundation of China(No.61605223)the Strategic Priority Research Program of Chinese Academy of Sciences(No.614A010717)the Director Fund of Advanced Laser Technology Laboratory of Anhui Province(No.AHL2021ZR06)。
文摘A numerical simulation model of plenoptic sensor aberration wavefront detection is established to simulate and analyze the detection performance of plenoptic sensor aberration wavefront for different turbulence intensities.The results show that the plenoptic sensor can achieve better distortion wavefront detection,and its wavefront detection accuracy improves with turbulence intensity.The unique optical structure design of the plenoptic sensor makes it more suitable for aberration wavefront detection in strong turbulent conditions.The wavefront detection performance of the plenoptic sensor is not only related to its wavefront reconstruction algorithm but also closely related to its structural parameter settings.The influence of structural parameters on the wavefront detection accuracy of plenoptic sensors under different turbulence intensities is simulated and analyzed.The variation law of wavefront detection accuracy and structural parameters under different turbulence intensities is summarized to provide a reference for the structural design and parameter optimization of plenoptic sensors.
