Abstract: A lightguiding device, which can be an integral part of a lightguiding system, can increase the light intensity exiting from a lightguide by concentrating the transmitted light into a small portion of the lightguide's cross section. The device consists of a section of a lightguiding material which has been bent at an angle greater than 45 degrees relative to the axis of light transmission, preferably at an angle of 90 degrees with a small bend radius. In the bent section, a homogeneous refractive index is required at least for the lightguide's core. The lightguide must be terminated immediately beyond the bent section. Alternatively, a preformed bent section of appropriate lightguiding material can be attached to an end of a straight section of lightguide to increase the exiting light intensity. All types of lightguiding systems can be used to enhance output intensities, including glass or pure silica lightguides, hollow waveguides, liquid core lightguides and plastic lightguides.

Abstract: A method and an apparatus for the selective determination of an isotope portion of a measuring gas by means of non-dispersive spectroscopy. The method includes sensitizing in a first ray path to the isotope component and sensitizing in a second ray path to the isotope-pure measuring gas, and electronically amplifying the measurement results. In order to improve the selectively and the sensitivity while maintaining a simple construction, an additional optical filtering is carried out in the first ray path by a filter filled essentially with isotope-pure measuring gas and the electronic measuring value of the second ray path is entered by influencing the amplification factor and an offset in the electronic amplification of the first ray path.