Selectivity and balance of spatial filtering velocimetry of objective speckles for measuring out-of-plane motion

Research output: Contribution to journalJournal articleResearchpeer-review

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.
Original languageEnglish
Article number047103
JournalOptical Engineering
Volume54
Issue number4
Number of pages10
ISSN0091-3286
DOIs
Publication statusPublished - 2015

Keywords

  • spatial filtering velocimetry
  • speckle phenomena
  • velocity sensor
  • Beamforming
  • CCD cameras
  • Dynamics
  • Velocimeters
  • Velocity measurement
  • Axial distance
  • Observation planes
  • Out-of-plane motion
  • Spatial filtering velocimetry
  • Spatial filters
  • Speckle dynamics
  • Speckle phenomenon
  • Velocity sensor
  • Speckle

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