Saturated absorption spectroscopy for spatially resolved flow velocimetry

This work develops a numerical model to present the potential of saturated absorption spectroscopy as a non-intrusive, spatially resolved diagnostic technique for velocity measurements in low-density rubidium-seeded gas flows. Lamb dips, formed by counter-propagating laser beams, act as sensitive markers of the local velocity distribution within the beam overlap region. By adjusting the intersection angle between the beams, the spatial extent of the overlap region can be controlled, enabling control over the sensitivity and spatial resolution of the measurement. Additionally, detuning the pump laser relative to the probe wavelength allows the measurement sensitivity to be optimized for specific velocity regimes. This technique proposes a precise and flexible approach for probing embedded flow structures in complex gaseous environments.