Characterization and verification of astigmatic interferometric particle imaging for volumetric droplet 3D position and size measurement

Abstract

Sprays generated by atomization processes have been used in a wide range of fields. The size and spatial distribution of volumetric droplets in a spray are critical parameters in industrial applications. Astigmatic interferometric particle imaging (AIPI), an extension of the traditional interferometric particle imaging (IPI), is developed to simultaneously measure the size and 3D position of volumetric droplets in a sparse spray. Based on the generalized Huygens–Fresnel integral and the transfer matrix, the size and depth position of droplet can be respectively extracted from the fringe spacing and orientation of interferogram in AIPI. An AIPI setup is established to characterize droplets in a sparse spray generated by a nozzle with the AIPI calibration procedure adopted. The measured parameters by AIPI are compared with those obtained synchronously by digital inline holography, which is regarded as a standard measurement technique. Results show that the average deviation values of droplet size and depth position are respectively 3.8% and 6.8%. AIPI has been demonstrated with high accuracy in simultaneous 3D positions and size measurements.