Abstract
This Letter describes the extension of saturated absorption spectroscopy to spatially resolved (point) absorption measurements for diagnostic applications. The technique modifies the standard configuration of Doppler-free saturation spectroscopy by using crossed, rather than counterpropagating, saturating and probe beams. The method is demonstrated in a study of the distribution of atomic sodium aspirated from a salt solution into an atmospheric-pressure hydrogen–air flame. Similar adaptations of other two-beam Doppler-free spectroscopic methods can be used to provide spatially resolved measurement techniques.