FFTs on a linear SIMD array

We discuss a device for real time compensaüon of image qnalzty deerioraion induced by aimospheric iurbulence. The device willpermit ground based observalions with very high image resoluiion. We propose an instrument with two channels. One is an ordinary image detection channel, while the other uses a Hartmann-Shack wavefront detector to measure image degradation. This information is obtained in the form of a set of lenslet focus shifts, each corresponding to the local tilt of the wavefront. Through modelling, the entire wavefront is reconstructed. Consequently, we can estimate the optical transfer function and its corresponding point spread function. Through convolution techniques, the distorted image can subsequently be restored. Thus, image correction is performed in software, eliminating the need for expensive live optics designs.Due to the nature of atmospheric turbulence, detection and correction have to be made with 50-100 frames per second. This implies a needfor very high computing capacity. A study ofthe mathematical operations involved has been made with special emphasis on implementation in the hardware architecture known as Radar Video Image Processor (RVIP). This hardware utilises a high degree ofparallelism. Results available show that RVIP together with complementary units provide the necessary high-speed computing capacity.The detection system in both channels must meet very high demands. We mention high quantum efficiency, f ast readout at low noise levels and a wide spectral range. A preliminary investigation evaluates suitable detectors. ICCDs are so far the most promising candidates.

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“…(4) and (2). The first part consists of2*C1*C1 MAC operations since each sub aperture requires 2 MAC operations.…”

Section: Architecture Mappingmentioning

confidence: 99%