Abstract: The invention relates to a method for monitoring a spectroradiometer (4), in particular for measuring light-emitting test objects (1), in which the spectral data of the test objects (1) are captured by means of an optical system, wherein the radiometric, photometric and/or colorimetric quantities of the test objects (1) are ascertained from the spectral data. The problem addressed by the invention is that of specifying a method for monitoring a spectroradiometer (4), where it is not the continuous recalibration of the spectroradiometer (4) but the monitoring of when a calibration is necessary that is paramount. The invention solves this problem by virtue of changes in the wavelength scale, in the light throughput and/or in the spectral sensitivity of the spectroradiometer (4) being detected by way of a reference light source (5), integrated into the optical system, with a defined spectrum.

Abstract: The invention relates to a method for monitoring a spectroradiometer (4), in particular for measuring light-emitting test objects (1), in which the spectral data of the test objects (1) are captured by means of an optical system, wherein the radiometric, photometric and/or colorimetric quantities of the test objects (1) are ascertained from the spectral data. The problem addressed by the invention is that of specifying a method for monitoring a spectroradiometer (4), where it is not the continuous recalibration of the spectroradiometer (4) but the monitoring of when a calibration is necessary that is paramount. The invention solves this problem by virtue of changes in the wavelength scale, in the light throughput and/or in the spectral sensitivity of the spectroradiometer (4) being detected by way of a reference light source (5), integrated into the optical system, with a defined spectrum.

Abstract: A method for purifying salt brine to obtain a highly pure sodium chloride from the purified brine by means of crystallization. Nanofiltration directly follows a two-stage brine purification according to the Schweizerhalle method, as a third purification stage, and the permeate of the nanofiltration is a highly pure brine. The concentrate from this step is recirculated into the first stage of the brine purification.