GB1486449A - Holographic apparatus - Google Patents

Abstract

1486449 Holography K VOCKENHUBER and R HAUSER 4 Sept 1974 [4 Sept 1973] 38599/74 Heading G2J Apparatus for use in holographic interferometry comprises, referring to Fig. 2, a source L of coherent light; a beam-splitter 4 giving rise to an object beam 1 and a reference beam 2; a first lens 11 for focusing the object beam 1 at a first point A lying between lens 11 and the object C and a second lens O, having an aperture stop centred on Q, for focusing the reflected object beam 1' on to the receiver 6 where it interferes with the reference beam 2. The apparatus is characterized by the first point A, or its conjugate, lying in or near the centre Q of the aperture stop of lens O so that rays to and from the object are substantially parallel. In Fig. 2, point A and the centre Q of the aperture cannot be made to coincide for practical reasons; in Fig. 3, however, this is achieved by focusing the object beam 1 at a point A which is coincident with the centre of aperture stop P and which lies on a partially reflecting mirror M through which the light reflected by the object C passes. The reference beam 2 is also brought to a focus at this point. In Fig. 4 (not shown) the object beam does not pass through lens O before reaching the object, as it does in Fig. 3. In Figs. 5 and 5A (not shown)the point of focus of the reflected object beam and the point of focus of the reference beam lie between the receiver and the lens O. In Fig. 6 (not shown) the point A lies on a semireflective mirror between lens O and object C. In Fig. 7 (not shown) the point of focus of the reference beam 2 is reflected so that its image lies within the aperture stop of the lens O. The receiver may be the screen 6 of a T.V. camera tube 7.