The TIFF image shows the formation of inkjet droplets captured at high-speed. They have a size of 20 micrometer and have an initial velocity of upto 20 m/s. These images were captured with a special 5-ns incoherent broad-band laser-induced fluorescence illumination technique which allows for a motion-free and speckle-free recording of the high-speed microdroplets. Selected Nature Magazine Image of the Year 2014 - see also Nature Research Highlights, Nature 507, 142 (2014).
Vaporization dynamics recorded at nanoseconds timescale: Acoustic droplet vaporization where superheated perfluorcarbon microdroplets are vaporized by a propagating shockwave containing many harmonics which leads to superharmonic focusing within the droplet - see also Shpak et al. PNAS 111, 1697-1702 (2014).
High-speed imaging is in popular demand for a broad range of experiments in fluids. It allows for a detailed visualization of the event under study by acquiring a series of image frames captured at high temporal and spatial resolution. The challenge here is the combined microscopic length scales and ultrashort time scales associated with the mechanisms controlling fluid flow, and bubble and droplet dynamics. Ultra high-speed imaging at frame rates exceeding 10 million frames per second will be reviewed, including turbine-driven rotating mirror cameras and the emerging ultrafast sensor technologies. I will also focus on ultrashort nanoseconds flash illumination techniques that shed new light on ultrafast processes in inkjet printing.
Michel Versluis was born in The Netherlands in 1963. He graduated with a degree in physics in 1988 from the University of Nijmegen, The Netherlands, with a special interest in molecular physics and astrophysics, working in the field of far-infrared laser spectroscopy of interstellar molecular species. Later, he specialized in the application of intense tunable ultraviolet lasers for flame diagnostics, resulting in a successful defense of his Ph.D. thesis in 1992. After a two-year research position working on molecular dynamics at Griffith University, Brisbane, Australia, he continued to work on developing laser diagnostic techniques for internal combustion engines (Lund, Sweden) and industrial jet flames and solid rocket propellants (Delft, The Netherlands). Dr. Versluis is now full professor Physical and Medical Acoustics at the University of Twente, The Netherlands, in the Physics of Fluids group. He is an expert in ultra high-speed imaging with a particular interest in the use of microbubbles and microdroplets for medical applications, both in imaging and in therapy, and in the physics and control of bubbles and droplets in microfluidic applications in medicine and the nanotechnology industry.