Development of a new digital camera setup for the online recording of Schlieren optical pictures in a modified Beckman Optima XL analytical ultracentrifuge

Abstract

Because Schlieren optical systems (e.g. essential for density gradients with steep refractive index gradients) are commercially not available a homemade system has been developed by transferring the existing Schlieren optics of a Beckman model E analytical ultracentrifuge to a preparative Beckman Optima XL analytical ultracentrifuge with an eight-cell multiplexer. In this paper we describe the expansion and further development of this system by introducing a new optical alignment that allows the online recording of Schlieren optical pictures using a digital camera. The digital black and white charge-coupled-device camera allows the control of the whole recording process, including, for example, control of picture brightness and contrast. Going along with the development of the physical setup, a new modular software concept has been worked out that clearly distinguishes three steps of picture recording, editing of the pictures and transforming them into analyzable data and finally analyzing the data with regard to the desired physical information. In this contribution details of the optical setup are described as well as the attendant software developments. Examples from industrial practice demonstrate the abilities and power of this new development in research and development applications as well as in routine industrial analytical measurements.

Acknowledgements The authors thank W. Mächtle for his great contributions in setting up the precursor Schlieren optical system and fruitful discussions during the setup of the new one. K. Reindel is acknowledged for his serious contributions to the installation of the camera and the data acquisition procedure. Thanks go to K. Vilsmeier for discussion of the software concept and for exemplary measurements. F. Hörner is acknowledged for help with the physical setup.