Showing papers on "Iterative reconstruction published in 1971"

Effect of emulsion thickness variations on wavefront reconstruction.

Abstract: In this paper an approach will be developed for wavefront recording and reconstruction with a photographic plate when emulsion thickness is not uniform. It is shown that in a first approximation an emulsion thickness variation will not affect the wavefront recording. However, thickness variation does affect the hologram image reconstruction. It is found that a first-order thickness variation (wedge-shaped), except for a lateral translation of image coordinates, will not affect the precision of the reconstruction. However, a second-order variation not only affects the precise dimension of the image reconstruction but also causes an astigmatic effect in the hologram image.

Resolution factors in edgeline holography.

Abstract: When an in-line Fresnel hologram of an object such as a projectile in flight is made, the reconstruction comprises an image of the outside edge of the object superimposed upon a Fresnel diffraction pattern of the edge and an unmodulated portion of the reconstruction beam. When the reconstructed image is bandpass filtered, the only remaining significant contribution is that of a diffraction pattern which is symmetrical about an edgeline gaussian image of the object. The present paper discusses the application of this type of holography in accurately locating the edge of a large dynamic object, the position of which is not accurately known in any dimension. A theoretical and experimental analysis was performed to study the effects of motion, hologram size, film type, and practical limitations upon the attainable resolution in the reconstructed image. The bandlimiting effect of motion is used to relate the motion effected resolution limit of holography to that of photography. The study shows that an edgeline can be accurately located even at high velocity normal to the edge.