Abstract: A method of reducing the effects of varying environmental conditions on a measuring instrument includes thermally insulating a measuring unit such that the effects of variations of environmental conditions on selected components of the measuring unit are substantially reduced, while allowing dissipated heat generated within the measuring unit to leave the measuring unit. The method also includes controlling a first temperature in the measuring unit by means of a control loop which includes a temperature sensor and means to influence the first temperature in the measuring unit in such a way that temperatures at locations with selected components are kept substantially constant.

Abstract: A method of reducing the effects of varying environmental conditions, such as varying temperature, on the measuring results in a measuring instrument, is disclosed as well as a corresponding measuring instrument using the method, for example an optical detector.

Abstract: A photometric absorption detector, in particular for the use in liquid chromatography is provided, in which a test cell is penetrated by the rays emitted by a light source and in which the absorption of certain wave length ranges of the light by the sample is recorded by means of a photodetector arrangement. Means for the spectroscopical dispersion of the light emerging from the test cell are provided, and the photodetector arrangement can be displaced within the spectrum. There may be two independently displaceable photodetectors, one of which may be set to a measuring wave length, while the other one may be set to a reference wave length.