Measuring device and method for detecting various gases and gas concentrations

The invention relates to a measuring device for detecting various gases and gas concentrations comprising an infrared radiation source, an optical path having measuring channel and arranged along the measuring channel radiation detectors, and a method which uses the measuring device. The object is to provide an optical measuring device with a significantly improved detection limit, which is compact and simple in construction and inexpensive to manufacture is, arrangement mutually solved in that the optical path has a deflection at least, wherein at a first deflection point a first band pass interference filter and the bandpass is disposed downstream of the interference filter, a first radiation detector. The object is achieved by a method comprising the steps of: introducing a measuring radiation in a the measuring duct, impingement of the measuring radiation contained gas to be measured on a valve disposed at a first deflection point first band pass interference filter, wherein only radiation of a through the first bandpass interference filter predetermined wavelength incident on a downstream of the band-pass interference filter radiation detector, forwarding the reflected on the band-pass interference filter radiation along the optical path in the measuring channel to a second radiation detector and evaluation of the measured with the radiation detectors gas concentrations.