Wave-front sensors are key elements of adaptive optics systems that compensate for aberrations encountered by a laser beam as it propagates through the atmosphere. Removing such aberrations are critical for applications such as high energy laser weapons, high bandwidth laser communication systems and precise target designators. AOptix has previously developed a wavefront sensor that directly measures wave-front curvature. Measuring wave-front curvature instead of the traditional practice of measuring wave-front slope offers significant advantages including immunity to scintillation and phase branch points (thus avoiding the need for wavefront reconstructors), absence of calibration and offset problems, higher efficiency and the use of one pixel per subaperture. When combined with a curvature deformable mirror, further benefits can be realized in the overall system performance. The proposed work will develop a novel curvature sensing wave-front sensor that is immune to branch-point errors, requires no reference calibration and will enable adaptive optic systems to operate with closed-loop bandwidth exceeding 1 kHz. Anticipated Benefits/Commercial Applications: The development of high speed wavefront sensors for adaptive optics has numerous potential commercial and military applications. Examples of such applications are: 1) High energy laser beam control for precise cutting, machining, surface heat treatment, marking and surface ablation, both in manufacturing and medical applications. 2) Laser communications through turbulent media. 3) Low energy laser beam control for scanning devices such as large format laser printers and 3D digitizers. 4) Focus and aberration control for confocal scanning microscopes. Applications 1) and 2) benefit from high speed, due to the intrinsic rapidity of processes to be corrected. Applications 3) and 4) benefit from high speed, since it allows for an increase in the scan rate of the devices. Utilization of AO for cutting and machining lasers, would allow more precise control of the tool spot size and shape. In AO-enhanced free space laser communications, quality of correction is currently limited by system speed. Higher correction speed will enable multi-gigabit military laser communications systems, such ground to air, air to air, and ground or air to space, and will enable robust commercial communications systems to work through a wide range of environmental conditions. For scanning applications, AO would allow for more precise beam control in the presence of thermal aberrations, turbulence aberrations, scanner induced aberrations or specimen aberrations. This could allow for a combination of cheaper optics, larger scan ranges, and enhanced resolution in a wide variety of applications.
Keywords: Adaptive Optics Wave-front sensor Shack-Hartmann Curvature sensing Speckle Scintillation
