Abstract: An axial fan has an impeller provided with vanes and mounted in a flow duct. In or on the wall of the duct at least one port is arranged adjacent to the vane tips. The duct side the port is provided with a covering means having passages therethrough.

Abstract: In a background compensation in material analysis, the value of the background signal is separated from the value of a gross analyte signal generated by athermal radiation excitation after thermal excitation. The thermal atomization takes place in a stepwise manner by stepwise heating and each step is divided into a first part for the measurement of the gross analyte signal and a second part for the measurement of the background signal.

Abstract: A method for the simultaneous analysis of several elements, in which the analyte, after a thermal vaporization, is athermally excited in the same volume by a hollow cathode discharge, assigns a discharge pressure range, in which the atomization temperature increases steadily with pressure, to the "cold" and "hot" hollow cathode discharge. The transition from one range to the other takes place suddenly. The discharge current intensity is increased with increasing atomization temperature.

Abstract: An apparatus for the positioning of ends of flexible light-conducting elements with the object of attaining a high position reproducibility of the fiber ends in an effective large-scale production technique, having the object of developing a technical solution so that it can be manufactured with a production technology in accordance with the accuracy requirements, so that a multitude of light-conducting fibers having defined positions are exactly fixedly correlated to defined positions. According to the invention, there are provided to one another essentially parallel thin surface elements which are secured at a distance and form an element package which is divided into two adjacent areas and within each one of the two areas there is provided at least an approximately equal distribution of pierced openings for the light-conducting elements.

Abstract: The invention relates to an optical system for spectral analysis devices particularly for use in atomic emission spectroscopy in which the aberrations, astigmatis and coma are compensated separately, comprising two concave spherical reflectors adjacently arranged and having their vertices equidistantly located relative to a center of a dispersing member. The latter has a dispersion plane at right angles to the dispersing structure of the dispersing member and to its surface, the vertices are located in said dispersion plane. The center beams originating from an excitation light source are reflected at the reflectors in reflection planes which are at right angles to the dispersion plane. The light entrance of the optical system comprises two slits the images of which coincide in a focal plane. The center of the focal plane and the light entrance have a same distance to the dispersion plane and are located on different sides of the latter.

Abstract: The invention relates to an optical system for spectral devices which improves the resolution of a spectral line image up to the edge portions by use of at least two collimators. The collimators are adjacently located in direction of dispersion and differently inclined relative to the plane of dispersion of the optical system. The produced spectral sections are imaged on a detector where the number of the collimators used depends on the number of spectral sections.