Alternative light sources for the Schlieren optical system of analytical ultracentrifuges.

This paper presents alternative light sources to the rather unreliable high pressure mercury lamps, commonly used for the schlieren optical system of Analytical Ultracentrifuges. The alternatives are an ultra-bright light emitting diode (LED) and a halogen lamp, which are both commonly available and very cheap. The non-uniform light emitted by these light sources is either transformed to uniform diffuse light with a ground glass or only the uniform parts of the light beam are used. This maintains a sufficient picture quality with constant light intensities for the lifetime of the light source which is much higher than that of a mercury lamp. For the example of a Beckman Model E ultracentrifuge, it is demonstrated that only minor alterations to the original lamp housing are necessary to transform the mercury light source into a halogen or LED one. The modified light source can be used in the same way as the original one and original alignment procedure of the Schlieren optical system can still be applied. Comparative Schlieren patterns are presented to demonstrate the picture quality achieved with each light source. The advantages and disadvantages of both light sources are discussed. [ABSTRACT FROM AUTHOR]