Development of optical multipass matrix systems

The basic principles of designing multipass matrix: systems (MMSs) are considered. A promising version of the MMS providing complete stability of the exit image is discussed. The new matrix system is versatile and most suitable, due to its potentialities and optical properties, for use in laser spectroscopy. A multipass transferable gas analyser comprising this matrix system and non-cooled diode lasers enabled record (for instruments of this type) sensitivity values to be achieved. In particular, the threshold sensitivity to methane is 0.02 ppm and the long-time stability of the measurements is 0.1 ppm. Designs of small large-aperture four- and six-row matrix systems are depicted.