Compressive Schlieren Deflectometry

Sudhakara Murthy, Prasad;Jacques, Laurent;Dubois, Xavier;Antoine, Philippe;Joannes, Luc
(2013) International Conference on Acoustics, Speech and Signal Processing — Location: Vancouver, Canada (26.May.2013)

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Authors
  • Sudhakara Murthy, PrasadUCLouvain
    Author
  • Author
  • Dubois, XavierLambda-X, Nivelles
    Author
  • Antoine, PhilippeLambda-X, Nivelles
    Author
  • Joannes, LucLambda-X, Nivelles
    Author
Abstract
Schlieren deflectometry aims at characterizing the deflections undergone by refracted incident light rays at any surface point of a transparent object. For smooth surfaces, each surface location is actually associated with a sparse deflection map (or spectrum). This paper presents a novel method to compressively acquire and reconstruct such spectra. This is achieved by altering the way deflection information is captured in a common Schlieren Deflectometer, i.e., the deflection spectra are indirectly observed by the principle of spread spectrum compressed sensing. These observations are realized optically using a 2-D Spatial Light Modulator (SLM) adjusted to the corresponding sensing basis and whose modulations encode the light deviation subsequently recorded by a CCD camera. The efficiency of this approach is demonstrated experimentally on the observation of few test objects. Further, using a simple parametrization of the deflection spectra we show that relevant key parameters can be directly computed using the measurements, avoiding full reconstruction.
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Citations

Sudhakara Murthy, P., Jacques, L., Dubois, X., Antoine, P., & Joannes, L. (2013). Compressive Schlieren Deflectometry. Proceedings of ICASSP 2013, p. 5999-6003. https://doi.org/10.1109/ICASSP.2013.6638816