Gas concentration measuring apparatus

A gas measuring apparatus for measuring a gas sample of inhalation anesthetics, carbon dioxide and nitrous oxide, the apparatus comprising:

• radiation source means for emitting radiation in first and second spectral ranges (Δλ1, Δλ2);
• a measuring gas cuvette for accommodating the gas sample to be examined;
• a mirror assembly including:
• first and second reflecting mirrors disposed at a distance from each other;
• and, means for changing said distance between said mirrors;
• said mirror assembly being configured on the basis of an electrically tunable Fabry Perot interferometer which provides transmissions corresponding to said first and second spectral ranges (Δλ1, Δλ2);
• a detector element for evaluating said first and second spectral ranges (Δλ1, Δλ2);
• and,
• a drive unit connected to said mirror assembly for presetting a dynamic range with a frequency (f2) for changing said distance so as to permit a first spectral range (Δλ1) to be detected in a transmission range of between approximately 3.5 micrometers and 4.5 micrometers and a second spectral range (Δλ2) to be detected in a transmission range of between approximately 8 micrometers and 12 micrometers.