The signal-to-noise ratio is a measure used in engineering and science that compares the level of a desired signal to the level of background noise. This parameter is one of the main features of the spectrometer devices. In this experimental study, a homemade photoacoustic layout used to detect chloroform vapour in the presence of krypton buffer gas. The system limit of detection for detecting chloroform was measured 475ppb at the 0.49W carbon dioxide laser power, 605Hz resonant frequency and in the presence of 1bar krypton gas. Also the system signal-to-noise ratio variations for 690 mTorr chloroform vapours in the presence of three buffer gases (krypton, N2 and He) at the various laser power and barometric pressure was measured. Results show that signal-to-noise ratio increase, when the carbon dioxide laser power increases. Also when He used as buffer gas, signal-to-noise ratio is the lowest.
