Optical gas analysis device having an electro-optically modulatable notch filter

摘要

An optical gas analysis device having a light beam running between a light source and a light receiver, in which a gas path and a notch filter are arranged, which has at least one birefringent element arranged between two polarisation filters, of which at least one element modulates the spectral optical transmission curve of the notch filter when an electric voltage is applied, is characterised in that the modulating element is subdivided in a direction transverse to the electric field strength into layers which have electrodes at the separating surfaces, which are capable of being loaded with voltage in such a way that essentially the same amount of electric field strength prevails in all layers, the layers being oriented with their crystal axes in such a way that the resulting optical delay is essentially the same for all layers.