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We describe a compact laser beam profiler that records multiple images of a laser beam at different positions along the beam waist in a single shot. This is used to determine the laser beam parameter M2. It is known that if light is incident on a curved grating such as a section of a Fresnel zone plate, then the +1 and -1 diffracted orders are focused or defocused. By combining two curved gratings and a conventional lens, it is possible to build a system in which a mosaic of nine images are created, corresponding to nine separate object planes. These nine images can be processed and fitted to an appropriate beam profile. This type of system measures beam quality in real time without any moving parts, and has the potential to provide real time monitoring of pulsed lasers, lasers with dynamic spatial behaviour, and in systems where beam handling optics may produce transient aberrations. Unlike other 'single shot' techniques, this technique makes no assumptions about beam propagation, and produces a value of M2 based only on measurements of beam waists.

An adaptive optics system usually has three basic elements, a wavefront sensor, a deformable element, and a feedback scheme. Typically these components are a Shack-Hartmann sensor, a bimorph or segmented mirror, and a DSP solution for performing the necessary calculations. These components are expensive, and give rise to a complex optical and computational system. In this paper a novel implementation of an adaptive optics system will be discussed. The wavefront sensor is based on an IMP grating to measure the curvature of the incoming light. This sensor has been found to be robust to scintillation, so is applicable to horizontal propagation paths. An OKO technologies deformable mirror is used, and the feedback loop calculations run on a standard Pentium III computer using Windows 2000. Results from recent trials of the system correcting for errors over various horizontal propagation lengths will be shown. Additionally results using this system for laser beam propagation will also be discussed.

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.