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Modified Sub-aperture Stitching Algorithm using Image Sharpening and Particle Swarm Optimization
Yiwei Chen,Erlong Miao,Yongxin Sui,Huaijiang Yang 한국광학회 2014 Current Optics and Photonics Vol.18 No.4
This study proposes a modified sub-aperture stitching algorithm, which uses an image sharpening algorithm and particle swarm optimization to improve the stitching accuracy. In sub-aperture stitching interferometers with high positional accuracy, the high-frequency components of measurements are more important than the low-frequency components when compensating for position errors using a sub-aperture stitching algorithm. Thus we use image sharpening algorithms to strengthen the high-frequency components of measurements. When using image sharpening algorithms, sub-aperture stitching algorithms based on the least-squares method easily become trapped at locally optimal solutions. However, particle swarm optimization is less likely to become trapped at a locally optimal solution, thus we utilized this method to develop a more robust algorithm. The results of simulations showed that our algorithm compensated for position errors more effectively than the existing algorithm. An experimental comparison with full aperture-testing results demonstrated the validity of the new algorithm.
Phase Only Pupil Filter Design Using Zernike Polynomials
Jiang Liu,Erlong Miao,Yongxin Sui,Huaijiang Yang 한국광학회 2016 Current Optics and Photonics Vol.20 No.1
A pupil filter is a useful technique for modifying the light intensity distribution near the focus of anoptical system to realize depth of field (DOF) extension and superresolution. In this paper, we proposeda new design of the phase only pupil filter by using Zernike polynomials. The effect of design parametersof the new filters on DOF extension and superresolution are discussed, such as defocus Strehl ratio (S.R.),superresolution factor (G) and relative first side lobe intensity (M). In comparison with the other two typesof pupil filters, the proposed filter presents its advantages on controlling both the axial and radial lightintensity distribution. Finally, defocused imaging simulations are carried out to further demonstrate theeffectiveness and superiority of the proposed pupil filter on DOF extension and superresolution in an opticalimaging system.
Fast Sub-aperture Stitching Algorithm Using Partial Derivatives
Yiwei Chen,Erlong Miao,Yongxin Sui,Huaijiang Yang 한국광학회 2015 Current Optics and Photonics Vol.19 No.1
For large optical elements which are tested by many sub-apertures, it takes too much time for asub-aperture stitching algorithm to get the stitching result. To solve this problem, we propose a fastsub-aperture stitching algorithm to quickly compensate for piston, tilt, and defocus errors. Moreover, thenew algorithm is easy to understand and program. We use partial derivatives of measurement data toseparately solve piston, tilt, and defocus errors. First, we show that the new algorithm has a lower timecomplexity than the currently used algorithm. Although simulation results indicate that the accuracy ofthe new algorithm is lower than the current algorithm in all 20 simulations, our experimental results validatethe algorithm and show it is sufficiently accurate for general use
Optimization of Wavefront Coding Phase Mask Applied to 5X-40X Micro-Objectives Simultaneously
Jiang Liu,Erlong Miao,Yongxin Sui,Jianghuai Yang 한국광학회 2015 Current Optics and Photonics Vol.19 No.5
A wavefront coding (WFC) technique provides an extension of the depth of field for a microscopyimaging system with slight loss of image spatial resolution. Through the analysis of the relationship betweenthe incidence angle of light at the phase mask and the system pupil function, a mixing symmetrical cubicphase mask (CPM) applied to 5X-40X micro-objectives is optimized simultaneously based on point-spreadfunction (PSF) invariance and nonzero mean values of the modulation transfer function (MTF) near thespatial cut-off frequency. Optimization results of the CPM show that the depth of field of thesemicro-objectives is extended 3-10 times respectively while keeping their resolution. Further imagingsimulations also prove its ability in enhancing the defocus imaging
Error-immune Algorithm for Absolute Testing of Rotationally Asymmetric Surface Deviation
Yanwei Zhang,Dongqi Su,Le Li,Yongxin Sui,Huaijiang Yang 한국광학회 2014 Current Optics and Photonics Vol.18 No.4
Based on Zernike polynomial fitting, we propose an algorithm believed to be new for interferometric measurements of rotationally asymmetric surface deviation of optics. This method tests and calculates each angular surface by choosing specified rotation angles with lowest error. The entire figure can be obtained by superimposing these sub-surfaces. Simulation and experiment studies for verifying the proposed algorithm are presented. The results show that the accuracy of the proposed method is higher than single-rotation algorithm and almost comparable to the rotation-averaging algorithm with fewer rotation measurements. The new algorithm can achieve a balance between the efficiency and accuracy.
Chuanyang Liang,Wei Zhang,Zhihui Wu,Dawei Rui,Yongxin Sui,Huaijiang Yang 한국광학회 2017 Current Optics and Photonics Vol.1 No.1
The laser has been regarded as the potential illumination source for the next generation of projectors. However, currently the major issues in applying the laser as an illumination source for projectors are beamshaping and laser speckle. We present a compact solution for both issues by using a vibrating diffractiveoptical element (DOE). The DOE is designed and fabricated, and it successfully transforms the circularGaussian laser beam to a low speckle contrast uniform rectangular pattern. Under a vibration frequencyof 150 Hz and amplitude of 200 μm, the speckle contrast value is reduced from 67.67% to 13.78%, andthe ANSI uniformity is improved from 24.36% to 85.54%. The experimental results demonstrate thefeasibility and potential of the proposed scheme, and the proposed method is a feasible approach to theminiaturization of laser projection display illumination systems.
Liang, Chuanyang,Zhang, Wei,Wu, Zhihui,Rui, Dawei,Sui, Yongxin,Yang, Huaijiang Optical Society of Korea 2017 Current Optics and Photonics Vol.1 No.1
The laser has been regarded as the potential illumination source for the next generation of projectors. However, currently the major issues in applying the laser as an illumination source for projectors are beam shaping and laser speckle. We present a compact solution for both issues by using a vibrating diffractive optical element (DOE). The DOE is designed and fabricated, and it successfully transforms the circular Gaussian laser beam to a low speckle contrast uniform rectangular pattern. Under a vibration frequency of 150 Hz and amplitude of $200{\mu}m$, the speckle contrast value is reduced from 67.67% to 13.78%, and the ANSI uniformity is improved from 24.36% to 85.54%. The experimental results demonstrate the feasibility and potential of the proposed scheme, and the proposed method is a feasible approach to the miniaturization of laser projection display illumination systems.