LIMITATIONS OF SIMPLE COHERENT OPTICAL SYSTEMS.
DUNTLEY (S Q) LA JOLLA CALIF
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The Fourier transform relationship between the front and rear focal planes of a simple lens has been used extensively in recent years. One important application has been that of attempting to restore degraded imagery by Fourier transforming the degraded imagery by Fourier transforming the degraded image, performing filtering in the Fourier plane, and accomplishing a second Fourier transform to obtain the restored image. These techniques have direct application to the problem of restoring images degraded by atmospheric turbulence and apply equally well to both temporally variant and temporally invariant degradation. The present report shows that the Fourier transform property is an approximation valid only for low spatial frequencies. At high spatial frequencies the Fourier transform achieved by a simple lens has serious phase errors. These phase errors will place severe limitations upon image restoration operations involving imagery with high spatial frequency content. Author