Holographic Microscopy

Abstract

THE use of holography¹ on a restricted class of objects in the visible spectrum was recognized by Gabor² and Parrent et al.³, but a problem occurred in the contrast of the reconstructed image owing to the presence of zero-order light, as no angular interference of the object and reference beams was used. Leith and Upatnieks⁴ as well as Lohman⁵ have described a technique which makes possible holography on more general and non-microscopic objects. This same technique was used to perform holography without the use of a lens on small objects by Leith and Upatnieks⁶. In experiments which we have carried out on more general objects, the optimum lower level of detectability was about 12µ when holography was performed without a lens. However, the experimental difficulties of obtaining a resolution of about 5µ are very serious. We have used a microscope (objective lens) to record holographically microscopic images of a general character. Although the attractive feature of ‘lens-less’ imagery was not used, the ability to record a substantial depth, as well as phase information in the object, has been preserved.