A monolithic microprocessor-controlled tuning and triggering system of TEA CO_2 laser for differential absorption lidar

摘要

In the present work, directed toward using differential absorption lidar (DIAL) for measuring concentrations of pollutant gases, a monolithic microprocessor-controlled tuning and triggering system for rapidly tuning a TEA CO_2 laser is reported. It is shown that it is possible to utilize a high frequency stepping motor and a diffraction grating to rapidly select wavelength over rotational transitions in the 9.2-10.8 μm region of the laser spectrum. The tuning is performed by applying appropriate signals to the stepping motor, which is coupled to the grating via a precision gear box. The microprocessor controls motion of the motor which rotates the correct angle for a given wavelength together with the grating. Many of pollutants have strong absorption lines in the 9-11 μm region, therefore the wavelength tunable transversely excited atmospheric-pressure (TEA) CO_2 laser becomes an ideal optical source for DIAL.