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Wei L.,CAS Chengdu Institute of Optics and Electronics | Zeng T.,Sichuan Institute of Supervision and Testing on Electronic Product | Lu Y.-H.,Shanghai SUPORE Instruments Co. | Jiang X.-P.,Shanghai SUPORE Instruments Co. | And 2 more authors.
Guangdian Gongcheng/Opto-Electronic Engineering | Year: 2012

A fast ellipse center computation algorithm is proposed for optical power-meter to make it highly-accurate and fast, considering that the spots of optical power-meter may be deformed, partial absent or double reflected and the goal of the spot calculation is just to obtain the centroid. The edge of the measured spot is obtained by bi-value morphology. With improved RANSAC method, the false edge points are eliminated for ellipse fitting. And the center of the ellipse, which is also the center of the measured spot, is directly calculated from the fitted coefficient of the ellipse. Experimental result shows that, when applied to optical power-meter, the proposed algorithm is fast and as accurate as the traditional Hough Transform -0.01D and it is suitable for practical application. Source


Wei L.,CAS Chengdu Institute of Optics and Electronics | Yang J.-S.,CAS Chengdu Institute of Optics and Electronics | Shi G.-H.,CAS Chengdu Institute of Optics and Electronics | Wang F.,CAS Chengdu Institute of Optics and Electronics | And 4 more authors.
Guangdian Gongcheng/Opto-Electronic Engineering | Year: 2012

An automatic method of searching and matching sub-aperture for Shack-Hartmann Wavefront Sensor (SHWFS) is introduced to enlarge the dynamic range of SHWFS while maintaining its designed accuracy. Firstly, the threshold of the image is estimated. By taking a spot of near the center of the thresholded image as the reference center, other spots are searched horizontally and vertically and combined to retrieve the whole sub-aperture distribution. Finally, the sub-aperture distributions of two images are matched by shifting horizontally and vertically. The proposed method is verified experimentally. The result shows that this method can realize the automatic searching and matching of the sub-aperture of SHWFS and enlarge the dynamic range of SHWFS. Source

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