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Gao F.,Soochow University of China | Gao F.,Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province | Zhang X.,Soochow University of China | Zhang X.,Shanghai JiaoTong University | And 4 more authors.
Optics Letters | Year: 2016

The wavefront characteristics in 2D angular filtering on the basis of two orthogonal transmitting volume Bragg gratings (VBGs) is presented. The experimental results show that middle-high frequency wavefront distortions are efficiently suppressed with VBGs. The peak-valley value of the beam at a wavelength of 1053 nm reduces from 2.075λ to 0.209λ, and the root mean square value reduces from 0.207λ to 0.041λ. The wavefront power spectrum density shows that the wavefront distribution of the beam in medium and high frequencies is corrected by the VBGs. Additionally, the farfield distribution and focusing properties of the beam are improved. The beam Strehl ratio increases from 0.43 to 0.96, and the encircled energy improves from 95% energy at 4.01 mrad to 95% energy at 1.26 mrad. © 2016 Optical Society of America. Source


Chen X.,Soochow University of China | Chen X.,Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province | Chen X.,Key Laboratory of Modern Optical Technologies of Education Ministry of China | Shen W.,Soochow University of China | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Phase retrieval method can determine pupil phase directly from image formed by the optical system with no extra hardware. This method has attracted more and more attentions for its unique advantage, and has been successfully applied in many domains such as large telescope alignment, X-ray imaging and so on. In this paper, we propose a hybrid phase retrieval method for annular pupil, which is composed of two steps. In the first step, the estimated spot images is computed with analytic expression, while fast Fourier transform is used in the second step. This method can achieve high retrieval speed without sacrificing the retrieval accuracy. Numerical simulation is performed to validate this phase retrieval method. © 2014 SPIE. Source


Chen X.,Soochow University of China | Chen X.,Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province | Chen X.,Key Laboratory of Modern Optical Technologies of Education Ministry of China | Shen W.,Soochow University of China | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

In this paper, we propose an aberration retrieval method for annular pupils using proposed parametric model of point spread function (PSF). With this model, the diffraction integral for annular pupils is expressed with Bessel-series representation and annular Zernike coefficients. Conjugate gradient algorithm is used to retrieve aberration coefficients of annular pupil from the corresponding spot intensity images. The iterative calculations of objective function and its gradient function are required for this algorithm. These calculations are accelerated by using the parametric model's analytical expression instead of Fourier transforms. Numerical simulation and experiment are performed to validate this aberration retrieval method. © 2012 SPIE. Source


Gao F.,Soochow University of China | Gao F.,Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province | Zhang X.,Soochow University of China | Zhang X.,Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

The wavefront characteristics in the angular filtering based on the transmitting volume Bragg gratings (VBGs) recorded in the photothermorefractive glass are discussed. The wavefront distortions were introduced in the super-Gaussian beam and the wavefront distribution of the diffracted beam was analyzed. Stimulation results show that the low frequency wavefront distribution with the period larger than 40mm is difficult to be corrected while the high frequency wavefront with period smaller than 0.1mm is easy to be corrected with VBGs. The middle-high frequency wavefront distortion with period between 5mm and 0.25mm can be effectively corrected with VBGs with the appropriate angular selectivity, and the PV values can be reduced 167 times and 1000 times than that of modulated beam, respectively. © 2016 SPIE. Source


Chen Y.,Soochow University of China | Chen Y.,Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province | Chen Y.,Key Laboratory of Modern Optical Technologies of Jiangsu Province | Chen Y.,Key Laboratory of Modern Optical Technologies of Ministry of Education and Jiangsu Province | And 16 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Compressive spectral imaging is a kind of novel spectral imaging technique that combines traditional spectral imaging method with new concept of compressive sensing. Spatial coding compressive spectral imaging realizes snapshot imaging and the dimension reduction of the acquisition data cube by successive modulation, dispersion and stacking of the light signal. It reduces acquisition data amount, increases imaging signal-to-noise ratio, realizes snapshot imaging for large field of view and has already been applied in the occasions such as high-speed imaging, fluorescent imaging and so on. In this paper, the physical model for single dispersion spatial coding compressive spectral imaging is reviewed on which the data flow procession is analyzed and its reconstruction issue is concluded. The existing sparse reconstruction methods are investigated and specific module based on the two-step iterative shrinkage/thresholding algorithm is built so as to execute the imaging data reconstruction. A regularizer based on the total-variation form is included in the unconstrained minimization problem so that the smooth extent of the restored data cube can be controlled by altering its tuning parameter. To verify the system modeling and data reconstruction method, a simulation imaging experiment is carried out, for which a specific imaging scenery of both spatial and spectral features is firstly built. The root-mean-square error of the whole-band reconstructed spectral images under different regularization tuning parameters are calculated so that the relation between data fidelity and the tuning parameter is revealed. The imaging quality is also evaluated by visual observation and comparison on resulting image and spectral curve. © Copyright SPIE. Source

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