The difference between laser sensing and traditional infrared sensing

　　At present, methane gas detection machines mainly use non-dispersive infrared online gas detector, as well as catalytic combustion methane detector. These instruments cannot quantitatively correct for cross-interference of background gases such as moisture and need to prevent dust in process gases from contaminating optical Windows in the analytical instruments.Therefore, before gas analysis, the sampling probe must be used to sample the process gas to be analyzed. The sample gas is removed by a complex pretreatment system after removing dust and water, and then sent to the gas analysis instrument for gas analysis. These gas analysis systems often have many defects, such as: Gas sampling and pretreatment system can not meet the requirements of analytical instruments, resulting in easy damage of instruments, short maintenance and overhaul cycle;The maintenance of sampling and pretreatment system is heavy and expensive. The system response time is too sluggish to meet the requirement of real - time control of industrial process.Both infrared methane detector and catalytic combustion methane detector have some inherent defects, which has become the bottleneck for enterprises to realize process control automation, but also restricts the development and application of gas detector.

　　TDLAS technology is essentially a spectral absorption technique that analyzes the selective absorption of a laser by a gas to obtain the concentration of a gas. It differs from traditional infrared spectroscopy in that the spectrum width of semiconductor laser is much smaller than that of gas absorption line.Through the molecular absorption wavelength of gas is independent of external temperature and pressure, and different gas molecules have non-interference wavelength absorption characteristics, so as to achieve not by the environmental temperature and humidity, not affected by interference gas.