The formation of a laser crown for a water drop. The radius of curvature of the drop hemisphere is about 3 mm. Frames are shown at , 1, 2, 5, 10, 18, 36, and , with an exposure duration of 500 ns. Scale bar is 1 mm. The bright circle in this and other images is an optical artifact. See also the online video clip (enhanced online). [URL: http://dx.doi.org/10.1063/1.3253394.1]10.1063/1.3253394.1
Setup of the laser and objective.
Laser-produced sheets. (a) Tip velocity of the sheet following the laser pulse. The horizontal broken line is the speed of sound in air. (b) The ejecta cone traced by the tip of the sheet following the laser pulse. The cone angle is .
Shape evolution for the cylindrical sheet. Times shown are , 2, 4, 7, 10, 15, and after the laser pulse.
Development of the cavity inside the water drop. Frames are spaced at 0, 8, 32, 96, 240, 336, 352, 448, 568, 656, and . The scale bar is 1 mm and , for laser energy of 30 mJ. The arrow points to the bottom of the air cavity (enhanced online). [URL: http://dx.doi.org/10.1063/1.3253394.2]10.1063/1.3253394.2
The suction of the fine spray into the growing crater for a water drop. The frames are separated by , with a 250 ns exposure. Scale bar is 1 mm, laser energy is 30 mJ, and .
Buckling of the cylindrical sheet. (a) Two superimposed frames, taken apart. (b) The arrow points to one of the vertical ridges. Frame exposure is 250 ns. Scale bar is .
Suction of spray into the crater from the crown wall for 80% glycerin drop, with viscosity . (a) , 24, 30, 34, 42, and after the laser pulse. (b) Close-up images of the sheet breakup, taken at , 14, 20, 23, 25, 28, 34, 48, 74, and . Note the direction of air marked by the arrows. Scale bars are both 1 mm, 30 mJ, at . See also the corresponding video clip taken at 1 Mframe/s (enhanced online). [URL: http://dx.doi.org/10.1063/1.3253394.3]10.1063/1.3253394.3
Changes in the laser disruption dynamics for de-ionized water as a function of the depth of the laser . Frames are selected to show the overall shape evolution and are not evenly spaced. (a) at . (b) at . (c) at . (d) at . (e) at . (f) at . Scale bars are 1 mm long and all laser pulses are 30 mJ.
The breakup of the crown wall, into a treelike shape, for a water drop at , 128, 284, and . The last frame shows the jet-and-collar shape. Laser pulse energy is 21 mJ and laser depth .
Bubble inside the water drop and undulations on the top surface. (a) The arrows point to the original laser pulse and the jet produced by the collapse of the bubble and is directed toward the solid wall. , 20, 160, 176, and after the laser pulse of 28.5 mJ. See also online video [URL: http://dx.doi.org/10.1063/1.3253394.4]. (b) Breakup of the free surface, shown at, 120, 200, 432, and after the laser pulse, of 30 mJ for . The arrows point to the bubble surface and the capillary waves coming from the contact line. The scale bars are 1 mm long. See also online video [URL: http://dx.doi.org/10.1063/1.3253394.5]. (c) The height of the protrusions above the original top of the drop vs time which is normalized by the time from the laser pulse to the first collapse of the internal bubble, where . (◻) The first protrusions on top of the drop during the expanding bubble and (▲) longer jets following the first collapse of the internal bubble (enhanced online).10.1063/1.3253394.410.1063/1.3253394.5
Changes in the ablated liquid as a function of the depth of the laser , for 75% glycerin drop with . (a) Laser spot at below the drop surface. Shapes shown at times , 10, 32, and . (b) Laser spot at , shown at , 44, 180, and . (c) Laser spot at , shown at , 136, 248, and . Scale bars are 1 mm long and laser energy is 30 mJ.
The laser disruption for 99% glycerin drop, with viscosity . The laser focus is moved further below the surface from the top to bottom rows. (a) , 4, 9, 17, and , for . (b) , 3, 5, 8, 12, 15, 22, 34, and , for . (c) , 32, 48, 64, 96, 160, 304, 736, and , for . (d) , 44, 100, 180, 236, and , for . Scale bars are 1 mm and laser energy is 30 mJ.
Large plasma generated above the ethanol surface, (a) for , 0, 1, 2, 3, 4, 5, 11, and . (b) For , 0, 1, 2, 3, 4, 5, 7, 15, 41, and . The scale bars are 1 mm and laser pulse energy is 30 mJ.
The breakup of the crown wall for an ethanol drop, for and , 2, 3, 4, 5, 8, 15, and . See also online video. Scale bar is 1 mm and laser pulse is 30 mJ (enhanced online). [URL: http://dx.doi.org/10.1063/1.3253394.6]10.1063/1.3253394.6
The holes forming in the crown wall for an ethanol drop for laser depth of . Four separate pocket formation sequences with the frames inside each row spaced by . Scale bars are .
(a) The breakup of the crown wall for an ethanol drop, , 30, 50, and . Scale bar is 1 mm, laser energy is 30 mJ and . (b) The paths of the tips of the fingers, such as those shown in (a).
Close-up imaging of the water spray. (a) The region in the close-up view is from a different video clip, taken at 15 times larger magnification. Scale bar is 1 mm. (b) Sequence of frames with . Scale bar is .
Example of a fine jet emerging from the top of a water drop. Panels shown for . This jet is about in diameter and emerges at 90 m/s. The scale bar is 1 mm and laser energy is 30 mJ at .
Laser-produced microjets from small bubbles sitting under the free surface, at the top of the hemispheric de-ionized water drop. The frames are spaced by , unless otherwise stated and the scale bars are all long. The laser depth and laser power of 30 mJ. (a) Fine jet, , which emerges at 170 m/s. The white arrow points to the faintly visible plasma showing the relative timing of the laser pulse and the start of the jet. (b) The emergence of a finer jet at 218 m/s. The first frames are spaced by and the last two frames are at 17 and after the first frame, showing the breakup of the jet into droplets. (c) The emergence of one very fine jet and another thicker one. The fine jet marked by the arrow (less than one pixel, i.e., ) emerges at 250 m/s. The thicker jet emerges at 120 m/s. (d) The emergence of two closely spaced jets. The last frame shows the breakup of the jets into drops and is taken after the plasma flash which is indicated by the arrow in the first frame. (e) Thicker jet, which is around (the thickness of a human hair) and emerges at 160 m/s. (f) Two fine jets, emerge at 240 m/s and (enhanced online). [URL: http://dx.doi.org/10.1063/1.3253394.7]10.1063/1.3253394.7
Forest of fine microjets, for drops of 60% glycerin/water mixture, with . (a) For laser depth of , at , 8, and . (b) For laser depth of , at , 4, and . Both scale bars are 1 mm long.
Jet velocity of the fastest fine jets observed for a given depth of the laser pulse below the surface. For a drop of 60% glycerin solution, with dynamic viscosity . The laser energy is 30 mJ.
Jet formation for 80% glycerin drop, with viscosity . Times shown are , 1, 2, 3, 4, 6, 8, 16, 19, 31, 43, and after the laser pulse of 30 mJ, at . Scale bar is 1 mm (enhanced online). [URL: http://dx.doi.org/10.1063/1.3253394.8]10.1063/1.3253394.8
Jet formation for 99% glycerin drop (, for ). (a) Times shown are 8, 16, 32, 56, 88, 232, and after the first image. (b) , 0, 16, 64, 96, 144, 304, and . The scale bars are 1 mm long, and laser energy is 30 mJ.
Bubble-produced jet for 99% glycerin drop, with . (a) Typical image used to measure the size of the bubble inside the drop (arrow). The microscope objective is clearly visible under the glass slide. (b) Images are shown at 0, 1, 2, 3, 4, 5, 7, 9, 11, 14, 20, and 26 frames after the laser pulse, taken from a video sequence of 460 kframes/s, thus having . The laser pulse is here about 15 mJ and its depth . The scale bar is long.
Irregular jet formation for an ethanol drop. (a) Times shown are 1, 4, 9, and after a laser pulse of 15 mJ. (b) , 5, 8, and after a laser pulse of 30 mJ. The scale bars are 1 mm long.
Properties of the different liquids used in the experiments.
Estimates of the spray droplet size for the different liquids.
Article metrics loading...
Full text loading...