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A recent comment has pointed out that some practically important aberration modes have zero curvature and in consequence seem difficult to sense using phase-diversity approaches that are equivalent to curvature sensing. Here we comment on the approaches that should be adopted when faced with a need to measure such aberration modes.

We describe a novel wave-front sensor comprising a distorted diffraction grating, simple optics, and a single camera. A noniterative phase-diversity algorithm is used for wave-front reconstruction. The sensor concept and practical implementation are described in detail, and performance is validated against different Zernike modes and a representative atmospheric phase map.