Abstract: A reflection fluorometer comprises a light guiding capillary with a fluorescent coating of the inner wall side, and a light source for excitation. The light source is positioned so that the light meets the outer longitudinal side of the capillary and part of the light penetrates the capillary. At least one sensor is positioned for sensing light at the front end of said capillary to measure the fluorescent light which leaves the capillary on that end. The capillary is constructed from light guiding material for the light that is excited in the area of the evanescent field, and the refractive index of an inner coating on the capillary is smaller than the refractive index of the capillary material.

Abstract: A reflection fluorometer has a cylindrical measuring optical waveguide with a capillary-like structure which permits a beam of pulsed light in the form of a conical envelope to be directed onto a front face of the measuring optical waveguide. The reflection fluorometer comprises a device for timed measurement of the emission light which emerges essentially radially from the measuring optical waveguide.