Most of the intelligent methods for drop-size distribution parameters,including number density and particle size,are through measurement of shade,light intensity or scattering energy generated by rain droplets and subsequent retrieval estimation.In this paper,photomicrography and embedded technology are adopted to develop an embedded microscopic imager for automatic measurement of droplet spectrum.After calibration in geometric scale,the instrument is settled on the roof of meteorological building in Nanjing University of Information Science & Technology,and is tested for real-time droplet collection and measurement in the fog or drizzly days of Nov.1,Nov.4 and Oct.28,2011.Preliminary tests show that 2D images of fog and rain drops between 5μm and 300μm can be directly derived in real-time by the instrument.The drop-size distribution parameters of fog and rain within this context can be given after image processing,hence the histograms of their number density are drawn.This instrument is convenient to be used for field experiments with characteristics of small size and light weight.The equipped touch screen allows several researchers to observe sample and share information at the same time.That pictures are taken in real-time and saved in digital files is convenient for data processing and management.