Abstract: A capnometer includes an airway adaptor for introducing a respiratory gas into the analyzer, an infrared radiation source emitting infrared radiation passed through the airway adaptor, a beam splitter for reflecting and transmitting infrared radiation that impinges on the beam splitter, first detecting means for detecting the infrared radiation reflected by said beam splitter and transmitting through said beam splitter, second detecting means for detecting the infrared radiation reflected by said beam splitter and transmitting through said beam splitter; a gas cell filled with CO2 gas, said gas cell being located between one of said first and second detecting means and said beam splitter and processing means for processing a concentration of carbon dioxide gas by using output signals of said first and second detecting means.

Abstract: The invention relates to a structure suitable for manufacturing by the fabrication techniques of micro-electronics so as to include an optically black surface that functions as an absorber or emitter, respectively, over a predetermined wavelength range, the structure includes a electrically nonconducting support layer (1), a metallic mirror layer (2) made on the support layer (1), and a lossy layer (4) made on the support layer (1) and the metallic mirror layer (2) superimposed thereon. According to the invention, the mirror layer (2) is made on the upper surface of the support layer (1) and the lossy layer (4) is made from a doped semiconductor material. The thickness of the multilayer structure (3, 4, 7) and the doping of the lossy layer (4) are predetermined relative to each other so that the mirror layer (2) will be optically matched over the predetermined wavelength range of absorption or emission, respectively, to the medium surrounding the structure.