METHOD AND APPARATUS FOR SPECKLE REDUCTION IN THE RECONSTRUCTION OF HOLOGRAPHIC IMAGES

摘要

1,252,621. Holography. AMERICAN OPTICAL CORP. Jan.3, 1969, No. 454/69. Heading G2J. A method of reconstructing images from holograms having reduced speckle backgrounds comprises directing coherent light 40 to a hologram so as to illuminate same and transmit therethrough, scattering the light from the coherent light source prior to its transmission through the hologram to produce a scattering pattern 62, 64 and continuously varying this scattering pattern produced. The scattering is preferably carried out using a ground glass plate 54 which is rotated in the path of the coherent light beam 40. The scatter surface 58 is constructed to give a predetermined maximum intensity lobe 62 and a series of random lobes 64 of much lesser intensity. From the knowledge of the maximum lobe 62 the maximum diameter "d" of the reconstruction spot RP can be determined from lines 68, 70 tangential to the sides of lobe 64 from a point in the scatter surface 58, which lines 68, 70 subtend an angle #. The Scatterer 54 is then located from RP a distance S # d/(2 tan #). In one embodiment the ground glass plate 54 is spaced 4 m.m. from the spot RP and has an operative portion passing through the light path 5 c. m. from its axis of rotation. Rotation was at 60 r.p.m. Examples are given for reconstruction in collinated and divergent light, and also where the hologram is used in microscopy.