Iterative design of a holographic beamformer.

A design method is presented for computing the phase functions of an energy efficient system using two holographic elements for converting a Gaussian beam into a uniform beam with rectangular support in the far field of the source. The method is based on a modification of the Gerchberg-Saxton algorithm which includes an x-y separability constraint on the phase of one of the holographic elements. A beamforming system was fabricated using this method, and experimental results were obtained which support the design approach.

Holographic polar formatting and realtime optical processing of synthetic aperture radar data.

A two holographic optical element (HOE) system for polar formatting of spotlight mode synthetic aperture radar (SAR) data was designed, fabricated, and successfully tested. With the addition of a spatial light modulator, a third phase-compensating HOE, and a Fourier transform lens, the real-time polar formatting of SAR data and SAR image formation was experimentally demonstrated.

Real-time digital aperture sampling sensor.

In real-time speckle imaging and speckle interferometry, there is often the need to remove a nonuniform incoherent background from the detected image to enhance the embedded coherent speckle image. Previous approaches generally require the use of a reference beam which makes the system very sensitive to mechanical instability. A new technique that operates on uncorrelated speckle images obtained by aperture sampling is proposed. The design of a real-time system for digital speckle image processing is described, and the experimental results are presented. Possible applications for the system on speckle interferometry are discussed.