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Chen X.,Soochow University of China | Chen X.,Jiangsu Key Laboratory of Modern Optical Technology | Shen W.,Soochow University of China | Shen W.,Jiangsu Key Laboratory of Modern Optical Technology
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

A fast phase retrieval method for annular pupil using spot image is proposed. The analytic formula to compute point spread function for annular pupil is derived. With this formula, the point spread function is represented as linear composition of polynomials, the coefficients of which are just the annular Zernike expansion coefficients of the pupil phase. The objective function and its gradient in phase retrieval for annular pupil are computed with this formula. It can avoid the Fourier transform and finite differences, which are necessary in common phase retrieval method, and decrease the computational burden in phase retrieval. The effectiveness of the proposed fast phase retrieval for annular pupil is demonstrated using numerical simulation and phase retrieval experiment. Experimental results indicate that the proposed method can improve the speed of phase retrieval for annular pupil effectively.


Chen X.,Soochow University of China | Chen X.,Jiangsu Key Laboratory of Modern Optical Technology | Shen W.,Soochow University of China | Shen W.,Jiangsu Key Laboratory of Modern Optical Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Spot-image based aberration retrieval method determines aberration directly from optical system's spot image with no extra hardware. In this paper, we propose a new spot-image based aberration retrieval method using the parametric model of point spread function (PSF). This model is built with scalar diffraction integral and its Bessel series representation. In this model, complex amplitude of PSF is represented by linear combination of function series with Zernike coefficients of wave aberration at pupil plane. With this PSF model, intensity distribution of spot image can be calculated without fast Fourier transform or numerical integration. Conjugate gradient method is used in our aberration retrieval routine and the proposed method is simulated with MATLAB. The retrieval results are satisfying for both noise-free and noisy star image. © 2011 SPIE.


Xiang C.,Soochow University of China | Xiang C.,Jiangsu Key Laboratory of Modern Optical Technology | Chen X.,Soochow University of China | Chen X.,Jiangsu Key Laboratory of Modern Optical Technology | And 6 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Modulation Transfer Function (MTF) is the spatial frequency response of imaging systems and now develops as an objective merit performance for evaluating both quality of lens and camera. Slanted-edge method and its principle for measuring MTF of digital camera are introduced in this paper. The setup and software for testing digital camera is respectively established and developed. Measurement results with different tilt angle of the knife edge are compared to discuss the influence of the tilt angle. Also carefully denoise of the knife edge image is performed to decrease the noise sensitivity of knife edge measurement. Comparisons have been made between the testing results gained by slanted-edge method and grating target technique, and their deviation is analyzed. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Chen X.-H.,Soochow University of China | Chen X.-H.,Jiangsu Key Laboratory of Modern Optical Technology | Ji Y.-Q.,Soochow University of China | Ji Y.-Q.,Jiangsu Key Laboratory of Modern Optical Technology | And 2 more authors.
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2012

A small-aberration retrieval method based on spot images was introduced and an analytic formula to computer the point spread function for a small aberration optical system was derived according to the scalar diffraction theory and Bessel series. With this formula, the objective function and its gradient were given for the small-aberration retrieval method. Then, the optimized method was used to solve this problem. The effectiveness of this method was demonstrated by using the numerical simulation under ideal and noisy conditions, respectively, and the influence of the size of spot object on the retrieval results was also analyzed. This method uses aberration's Zernike coefficients as optimization variants and computes the objective function and its gradient with analytic expressions to avoid Fourier transform or numerical integral needed in common aberration retrieval methods. Therefore, it improves the speed of aberration retrieval greatly.


Yiqun J.,Soochow University of China | Yiqun J.,Jiangsu Key Laboratory of Modern Optical Technology | Yiqun J.,Priority Academic Program Development of Jiangsu Higher Education Institutions | Rudong X.,Soochow University of China | And 14 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Based on the wave aberration theory, a new method of optical design of the planate symmetric Offner type imaging spectrometer is performed. Astigmatism changing with the diffraction angle of the grating, the meridional and saggital focusing characters are all studied. Determination of the initial configurations and optimally design methods of two improved types of Offner imaging spectrometer are discussed in detailed. A design example with the numerical aperture larger than 0.2, and the entrance slit 30mm is given. Its spectral resolution is better than 2nm and MTF is above 0.7@20lp/mm. The smile and keystone are less than 3% and 0.2% of the pixel respectively. © 2011 SPIE CCC code.


Zhou J.,Soochow University of China | Zhou J.,Jiangsu Key Laboratory of Modern Optical Technology | Shi R.,Soochow University of China | Shi R.,Jiangsu Key Laboratory of Modern Optical Technology | And 6 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

This paper presents a radiometric calibration method based on visibility function and uniform source system. The uniform system is mainly comprised of an integrating sphere and a monitoring silicon detector. The current of the silicon detector with a visibility function filter corresponds to the luminance at the exit port of integrating sphere through standard luminance meter transfer. The radiance at the camera entrance pupil is calculated for different solar zenith angles and Earth surface albedos by the MODTRAN atmospheric code. To simplify the calibration process, the radiance at its entrance pupil is integrated by visibility function. The shift smear of the frame transfer CCD is removed by the radiometric calibration and the amending ratio factor is introduced in the retrieving methods. The imaging experiment verifies the reliability of the calibration method and retrieves good quality image. © 2010 SPIE.

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