Abstract
The 'HAUP' method, described by Kobayashi and Uesu (1983-85), for the measurement of optical activity in birefringent crystals is extended to include dichroic effects and analysed qualitatively in a novel way using intensity contour maps. The elimination of the parasitic ellipticities of the polariser and analyser is achieved by repeating the measurement in a second crystal setting, rather than physically exchanging the prisms, which has been reported as unworkable.