Speckle pattern rotation and a detection scheme for its rotation angle

Makoto Hasegawa; Kohei Yamamoto; Yusuke Takahashi; Muneki Kawahara

doi:10.1117/12.2034369

19 September 2013 Speckle pattern rotation and a detection scheme for its rotation angle

Makoto Hasegawa, Kohei Yamamoto, Yusuke Takahashi, Muneki Kawahara

Proceedings Volume 8905, International Symposium on Photoelectronic Detection and Imaging 2013: Laser Sensing and Imaging and Applications; 89051J (2013) https://doi.org/10.1117/12.2034369
Event: ISPDI 2013 - Fifth International Symposium on Photoelectronic Detection and Imaging, 2013, Beijing, China

Abstract

When coherent light beams, i.e., laser beams are transmitted in an optical fiber and exit from one end to form an output light spot on a screen, non-uniform intensity distribution called speckle patterns is often recognized in the output light spot. The authors have confirmed that when a multimode optical fiber is placed in a loop or a U-shape onto a support plate and the support plate is rotated or tilted with the diameter of the loop or the longitudinal axis of the U-shape as the axis of the rotation or tilting motion, the speckle patterns appear to rotate in a certain direction. Such rotation phenomena of speckle pattern are observed with relatively good reproducibility, and the rotation angle of the speckle pattern is almost in proportion to the rotation or tilting angle of the support plate. In the authors’ previous reports, a rotation angle of speckle pattern was detected by manual work, which was tiresome and time-consuming task. This was also unrealistic if we are going to utilize the phenomena for some kinds of sensing application. In this paper, a new scheme for semi-automatically detecting the rotation angle of speckle pattern from image data before and after the pattern rotation is being tried. With this scheme, detection of the pattern rotation angle upon rotation or tilting of the support plate can be realized easily in a short period of time. The semi-automatic detection scheme has been actually employed to investigate rotation characteristics of speckle pattern in several different conditions.

Citation Download Citation

Makoto Hasegawa, Kohei Yamamoto, Yusuke Takahashi, and Muneki Kawahara "Speckle pattern rotation and a detection scheme for its rotation angle", Proc. SPIE 8905, International Symposium on Photoelectronic Detection and Imaging 2013: Laser Sensing and Imaging and Applications, 89051J (19 September 2013); https://doi.org/10.1117/12.2034369

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