A planar laser induced fluorescence measurement of the vapor mole fraction field is developed around acetone monodisperse droplet streams. An accurate calibration is performed with an acetone saturated hermetic cell. An interface positioning method based on the Lorenz–Mie theory and on the geometrical optic is proposed on the images with the liquid phase despite the blooming effect. This accurate position is necessary to eliminate the blooming subsequently by hiding the liquid phase. Quantitative results obtained with two different injection temperatures concur with the numerical simulations.