Improving the 13CO2 content measurement accuracy in exhaled air using the Kalman technique for filtering the experimental signal obtained by the tunable diode laser absorption spectroscopy method with the frequency modulation of the diode laser pump current

Abstract

This paper reports on the application of the Kalman method for processing the signal obtained by the tunable diode laser absorption spectroscopy method in an experimental circuit, which includes the frequency modulation of a diode laser pump current in combination with the synchronous detection technique. It has established that the implementing of this approach makes it possible to improve the measurement accuracy of the 13CO 2 content, as well as the measurement accuracy of the 13CO2 and 12CO2 concentrations ratio in exhaled air to a level not exceeding 0.1%.