On Line Data Acquisition for the Rayleigh Interference Optical System of the Analytical Ultracentrifuge

Abstract

The fundamental measurement in analytical ultracentrifugation is the concentration as a function of radial position. The Rayleigh interferometer of the analytical ultracentrifuge produces a cell image in which the concentration at each radial position is presented as the vertical displacement of a set of equally-spaced horizontal fringes (Richards and Schachman, 1959). Manual acquisition of data from interferograms is tedious and automated photographic plate readers still require that photographs be taken, processed, aligned and read before data analysis can be performed. Fortunately, a Rayleigh interference image is well suited for television- camera-based data acquisition. Described here are two types of automated Rayleigh interferometers for the Beckman Model E analytical ultracentrifuge. One type of system relays and magnifies the Rayleigh interference image from the usual photographic plane to a television camera located behind this plane. The other system uses a redesigned camera- cylinder lens combination to create a radially demagnified Rayleigh interference image of the cell on the television camera sensor located on the original cylinder lens mount.