Cross-talk between different modes has always been an intrinsic issue of a modal wavefront sensor. Efforts have been put to reduce the effect of these inter-modal cross-talk either by varying the detector aperture or by changing the mode of intensity measurement at the detector. Since the modal wavefront sensor considers the incident wavefront as a linear combination of some orthogonal basis set, say the Zernike polynomials, the presence of cross-talk between the different modes of these basis set greatly affects the sensor output. As a result the measure of the modal content of the various orthogonal modes in the incident wavefront are affected, leading to inaccuracy in measurements. In this work we present a new method of measurement of the orthogonal modes present in an incident wavefront. The proposed method can be considered as a modified version of the modal wavefront sensing technique proposed by Neil et al, having advantages in terms of cross-talk reduction between modes and linearity enhancement, in the process of measurement of various orthogonal modes present in the incident wavefront. In this paper we also present some of our simulation results in support of our proposed sensing technique.

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Santanu Konwar and Bosanta R. Boruah, "Improvement in modal wavefront sensing in terms of cross-talk reduction and linearity ," Proc. SPIE 10772, Unconventional and Indirect Imaging, Image Reconstruction, and Wavefront Sensing 2018, 107720D (Presented at SPIE Optical Engineering + Applications: August 22, 2018; Published: 18 September 2018); https://doi.org/10.1117/12.2319928.