Coherent wave imaging and/or recording technique for reducing the generation of spurious coherent-wave image patterns

摘要

A mask is used to sequentially illuminate successive elemental areas of an object (by changing the position of the mask) to obtain from each relatively small elemental area a diverging object-information component of coherent wave energy which is passed through a relatively large cross- sectional aperture of imaging and/or recording means. The fact that this cross-sectional aperture is so much larger in area than the area covered by any dust or optical defects of the imaging and/or recording means markedly reduces spurious coherent-wave patterns normally produced by such dust or optical defects. Further, since the illumination is not diffuse, no speckle pattern problem exists.