Anordnung zum Bewerten eines Messsignals nach Betrag und Phase in Bezug auf ein Referenzsignal

The invention relates to a setup for evaluating a measuring signal for its amount and phase in relation to a reference signal and is used preferably in optical spectroscopy for building a measurement setup for trace gas analysis using modulated laser radiation, e.g., that of a diode laser. The invention proposes the simultaneous operation of single-tone and double-tone systems for modulating and demodulating the signal of the diode laser, whereby evaluation of the measuring signal is simplified. The main feature here is that a decision can be made a priori as to which modulation or demodulation process can be given preference. As a result of the flexibility of the solution proposed by the invention, it is possible to select an optimum technology suited to the given conditions. Since all components can be designed to be computer-controlled, computer-controlled optimization is possible. As a result of the invention, high modulation frequencies are achievable and it can be applied in rapi d-tuning cw systems and in pulsed laser spectroscopy systems. By reducing interfering harmonics in the modulation signal and as a result of the interference-free reference signal, the signal-to-noise ratio of the actual measuring signal is increased. Moreover, a high time resolution of the measuring signals can be achieved and, as a result of modular design and signal and connection compatibility with known design forms, old waste sites can be cost-effectively..