9 April 2015 Selectivity and balance of spatial filtering velocimetry of objective speckles for measuring out-of-plane motion
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Abstract
We probe the dynamics of objective laser speckles as the axial distance between the object and the observation plane changes. With the purpose of measuring out-of-plane motion in real time, we apply optical spatial filtering velocimetry to the speckle dynamics. To achieve this, a rotationally symmetric spatial filter is designed. The spatial filter converts the speckle dynamics into a photocurrent with a quasi-sinusoidal response to the out-of-plane motion. Our contribution presents the technology, discusses the selectivity of the spatial filter and proposes two solutions to balance phase-stepped photocurrents. Specifically, we discuss how the selectivity of the spatial filter with regard to radial speckle motion is influenced by a concurrent in-plane speckle motion. The spatial filter is emulated with a CCD camera and is tested on speckle acquisitions obtained from a controlled setup. Experiments with the emulated filters illustrate the performance and potential applications of the technology.
© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
Michael Linde Jakobsen, Michael Linde Jakobsen, Hal T. Yura, Hal T. Yura, Steen Grüner Hanson, Steen Grüner Hanson, } "Selectivity and balance of spatial filtering velocimetry of objective speckles for measuring out-of-plane motion," Optical Engineering 54(4), 047103 (9 April 2015). https://doi.org/10.1117/1.OE.54.4.047103 . Submission:
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