On-line digitalization of Schlieren pictures inside the analytical ultracentrifuge

Abstract

A rationalization of the analytical ultracentrifuge (AUC) is reported that also improves the accuracy of measurement with sedimentation runs controlled by Schlieren optics. A digital video camera was inserted into the optic beam of the AUC which detects Schlieren pictures on-line by means of an attached computer and evaluates them by instantaneous data reduction. Thus the photographic production of Schlieren pictures and their time-consuming manual evaluation can be avoided. With the new technique, a reference cell, a dark current cell, a brightness distribution cell, and five sample cells are simultaneously measured within an eight-cell rotor. Either a triggerable laser or a flashlight serves as a light source. Every 25 s, a Schlieren picture can be recorded and then be evaluated on-line by means of image processing.