High Speed Imaging and Analysis of Jet and Drop Formation

New techniques have been developed for analyzing in detail the shape and development of ink jets and drops. By using flash illumination of very short duration (ca. 20 ns), high-quality, singleevent digital images of jets and drops can be captured. A computer program, PEJET, has been written to automate the processing of such images and to generate quantitative data about the whole ink stream. From this data it is then possible to compute the variation in fluid volume, volume flow and velocity as a function of both position and time. The method has been shown to have high accuracy. The results can be used to study the influence of nozzle design, drive waveform and fluid properties on jet and drop formation, as well as to provide accurate data for comparison with the results of computational modelling.Examples of typical results from a drop-on-demand system are presented that illustrate the potential of the method to compare quantitatively the performance of print systems and inks.