Draft:MLSI

=Multilateral shearing interferometry=

Multilateral shearing interferometry (MLSI) is a family of wavefront imaging techniques that are based on the association of a 2-dimensional diffraction grating and a camera sensor in close proximity. MLSI was developed in the 90s, first with diffraction gratings featuring a 3-fold symmetry. In 2000, quadriwave lateral shearing interferometry (QLSI) was introduced and patented. This particular implementation of MLSI uses a 4-fold symmetry grating, that consists of horizontal and vertical opaque lines defining transparent holes, on which 0 and π phase shifts are imprinted according to a checkerboard pattern. This particular design confers several valuable properties to the system. In particular, it makes the grating-camera association efficient for a wide range of wavelengths, and also make the grating-camera distance continuously adjustable, as a means to adjust the signal to noise ratio of the reconstructed wavefront distribution. QLSI has remained the main MLSI implementation used in the community.

The applications of MLSI include optical microscopy, laser characterization, material inspection and optics metrology. The MLSI principle has been also applied to the X-ray range.

Working principle
A QLSI grating consists of opaque horizontal and vertical lines defining transparent square holes, on which 0 and π phase shifts are imprinted according to a checkerboard pattern. This specific design makes the light diffraction pattern invariant by translation, making the measurements possible for any grating-camera distance.

History
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Microscopie optique
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