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.

A method for reconstructing an unknown wave front from measurements of its intensity distribution on two planes along the direction of propagation is described. The method solves the intensity transport equation by use of Neumann boundary conditions, leading to a solution that requires only matrix multiplication. The method provides real-time wave-front reconstruction with high accuracy and is easily reposed to permit reconstruction of the wave front in any orthonormal basis set.

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.

Turbulence effects close to the air-ground interface may be expected to be non-Kolmogorov, even if that model is an adequate description of free-air turbulence effects. Direct measurements of the optical effects of propagation through the boundary layer are therefore required and are being undertaken as part of a programme in which various potential applications of adaptive optics are being examined. The measurements are intended to characterise the spatio-temporal characteristics of optical wavefronts after propagation through the air-ground boundary layer. The objective in these measurements is to describe the level of performance that will be required in an adaptive system intended to mitigate the deleterious effects of atmospheric propagation on image formation and on other optical measurements. The principles of measurement and the preliminary results are presented.