Allowance for spatio-temporal and spectral inhomogeneities of laser pulses in determination of the saturation power by the optoacoustic method

An analysis is made of the errors resulting from lack of allowance for the spatio-temporal and spectral inhomogeneities of laser pulses in the determination of the true absorption coefficient of a molecular gas medium by the optoacoustic method and in the subsequent calculation of the saturation power of a resonance transition. A numerical analysis based on the rate equations is carried out in the quasistationary approximation for different shapes of the pulses and different spatial energy distributions. It is shown that for a certain spatial energy distribution the errors due to inaccurate knowledge of the pulse shape in time can be reduced. It is also shown that when the emission line width is less than one-fifth of the absorption line width, the nonmonochromaticity of the radiation makes a negligible contribution to the total error in the determination of the saturation power.