Microscopic characteristics of fluid spray are investigated using microscopic imaging. This includes particle size distribution and particle velocity. The microscope provides a close-up view to a small section of the spray as small as 1 mm2. Double frame images have been produced with a 5- 30 µs time separation between frames. Those images could be used to generate velocity vector maps. A histogram of particle size distribution can be obtained for evaluating the atomization performance of the injector. Shadowgraphy method along with Nd-YAG lasers are used for micro-imaging of the fluid droplets size between 4 and 50 micrometer in diameter.