Abstract: A measuring chamber device for an optically operating sensor for determining a concentration of a substance that is contained in tissue fluid of a mammal. The measuring chamber device has a measuring chamber filled with a liquid measuring medium and a wall with better diffusion permeability for the substance than for other constituents of the tissue fluid. A transmitter device for emitting optical radiation into the measuring chamber, and a receiver device for receiving optical radiation that has passed through the measuring chamber are also provided.

Abstract: To produce optical beam splitter cubes, an optically transparent plate is provided with an optically active layer on a cover side. Then, on both cover sides of the plate, a plurality of prism bars are formed by molding an optically transparent material, so that a double prism plate is obtained. The prism bars are arranged on cover sides of the plate projecting roof-like in ridge lines separated from each other by valleys. Each prism bar has the cross section of an isosceles right-angled triangle, complemented by the prism bar lying opposite on the other cover side of the plate to form the cross section of the beam splitter cube. The double prism plate is cut up along the valleys between the prism bars and transverse to the longitudinal direction into segments which in each case form a beam splitter cube.