Accession Number : ADP006768
Title : Crystal Noise Limited Holographic Interferometry in BSO,
Corporate Author : IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (UNITED KINGDOM) BLACKETT LAB
Personal Author(s) : Troth, R. C. ; Dainty, J. C. ; Sochava, S. L. ; Stepanov, S. I.
Report Date : 22 MAY 1992
Pagination or Media Count : 4
Abstract : There are two geometries that are generally used for real-time interferometry, the four wave mixing (FWM) and two beam coupling (TBC) geometries. There is, however, a geometry which incorporates features of both FWM and TBC proposed by Petrov et.al. and it is this geometry which is easiest to implement and gives good results. In this geometry the anisotropic self diffraction properties of sillenite crystals such as Bi,2(Ge, Si, Ti)02o are used to produce a polarization rotation between the incident and diffracted beams. Thus if one of the above crystals is placed in the standard FWM orientation , with the 110) crystalographic direction in the plane of the incident beams, such that the axes of charge induced birefringence are at +/-45 deg to the (001) direction (Fig.1), then the transmitted object (signal) two orthogonal polarizers placed in front of and behind beam can be cancelled by using' the crystal. This enables the diffracted image to be isolated from the signal so reducing the effective noise in the output hologram. Rather good time-average and double exposure interferograms can be produced, with, however, a restriction on the size of the object that can be investigated, when the object is diffusely reflecting. In the case of the time-average interferogram shown in (Fig.2) the object was only 40 mm in diameter.
Descriptors : *OPTICAL IMAGES, *HOLOGRAPHY, AXES, BIREFRINGENCE, CRYSTALS, DIAMETERS, DIFFRACTION, GEOMETRY, HOLOGRAMS, INTERFEROGRAMS, INTERFEROMETRY, NOISE, OUTPUT, POLARIZATION, POLARIZERS, REAL TIME, ROTATION, SIGNALS, REFLECTIVITY, REFRACTION, SYMPOSIA.
Subject Categories : Optics
Distribution Statement : APPROVED FOR PUBLIC RELEASE