sentences:  But if one uses a very high resolution spectrometer, it is possible to find some water peaks that are not overlapped by other gas peaks.The tunable laser provides a narrow, tunable wavelength light source that can be used to analyze these small spectral features.According to the Beer-Lambert law, the amount of light absorbed by the gas is proportional to amount of the gas present in the light’s path; therefore this technique is a direct measurement of moisture.