22-30 July 2021
North-West University
Africa/Johannesburg timezone
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Birefringence from digital phase-shifting measurements

27 Jul 2021, 12:15
Potchefstroom Campus (North-West University)

Potchefstroom Campus

North-West University

Oral Presentation Track F - Applied Physics Applied Physics


Keshaan Singh (University of the Witwatersrand)


Measuring phase differences between orthogonal polarisations has become a common industry practice. In food and drug production the circular birefringence exhibited by chiral molecules has been used to identify and measure the concentrations of enantiomers, while linear birefringence has been used in stress and biological imaging. Conventional techniques regularly rely on stressing photo-elastic materials to produce birefringence in order to measure the same phenomenon. We demonstrate how holographic phase shifting induced by a digital micro-mirror device (DMD) can be used to acquire spatially resolved arbitrary birefringence measurements. Linear and circular birefringence in both static and dynamic liquid crystal optics, metasurfaces as well as chiral sugar solutions were measured through maximum-likelihood estimation fitting. The acquired images have resolutions dependent purely on the camera used and the entire measurement process involves no moving parts. The polarisation and wavelength independence of DMDs as well as high refresh rates and relative low cost makes the technique a promising digital candidate for applications in industry.

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Primary authors

Keshaan Singh (University of the Witwatersrand) Wagner Tavares Buono (University of the Witwatersrand) Mr Manuel Fernandes (University of the Witwatersrand) Dr Angela Dudley Andrew Forbes (U. Witwatersrand)

Presentation Materials