  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.
