Plenoptic Wavefront Sensing for Tactical Systems

Wavefront sensors for adaptive-optics systems have traditionally been used in conditions where atmospheric turbulence is relatively weak and concentrated near the pupil of the optical system. Several generations of rotating radial grating, Shack-Hartmann, and modal wavefront sensors have been developed and fielded over the last several decades to compensate atmospheric turbulence. More recently, the need to perform adaptive optics compensation for strong and distributed turbulence has kindled interest in new wavefront sensor designs that must perform where the local rms wavefront gradients exceeds several wavelengths per subaperture. In addition, the wavefront sensors are expected to operate passively, using information from a complex scene to determine the refractive distortion. Nanohmics proposes to build, test, and demonstrate a new type of wavefront sensor that measures the four-dimensional light field. The design of the sensor is reminiscent of an extended-scene Shack-Hartmann wavefront sensor, but operates in a completely different manner that is suitable for the measurement of large wavefront gradients in an extended, passive scene, even in the presence of significant scintillation. The concept originates from previous work done in the area of plenoptic imaging, and parallels more recent work done with light-field photography and passive rangefinding.