OPTICAL LONG-PATH GAS MONITORING APPARATUS

摘要

OPTICAL LONG-PATH GAS MONITORING APPARATUS Optical long-path gas monitoring apparatus (2) comprising means (4) for providing a radiation beam, a modulator (10) for modulating the wavelength of the radiation beam such as to produce amplitude modulation of the beam in the presence of the gas being monitored, a radiation detector (12) for conversion of the radiation beam into an electrical signal, and a signal processor (PSD 1,PSD 2) for demodulating the electrical signal to provide a signal dependent upon the gas.