Research ArticleAPPLIED ACOUSTICS

Laser streaming: Turning a laser beam into a flow of liquid

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Science Advances  27 Sep 2017:
Vol. 3, no. 9, e1700555
DOI: 10.1126/sciadv.1700555
  • Fig. 1 Experimental setup and streams at different incident angles of lasers.

    (A) Schematic. A video camera with variable exposure time is used to capture the motion of streams. The thickness of the cuvette wall is 1 mm. (B) The cuvette is tilted to vary the incident angle. (C to F) Optical images of streams at incident angles of (C) 0°, (D) 10°, (E) 20°, and (F) 30°. White dashed line indicates the cuvette surface, and white block arrows indicate the directions of flows and laser propagation. The angle in the water becomes smaller because of refraction. Laser power is 120 mW. The exposure time for each shot is 100 ms. The trajectory lengths of polymer microspheres are proportional to the flow speed at that point and can be calculated from speed scale bars.

  • Fig. 2 Flows and flow patterns at normal incidence under decreasing laser powers.

    A 633-nm HeNe laser was used to illuminate tracing microspheres, and a long-pass filter was used to block 527-nm light. The optical path length of the cuvette is 1 cm. The exposure time is 50 ms. White dashed lines indicate cuvette surfaces, and (A) is downstream and (B) is upstream of the flow under 120-mW laser. (C) to (H) are upstream flows under different laser powers as in (B).

  • Fig. 3 Electron micrographs and optical profiles of microcavities created by the laser.

    (A to D) Scanning electron micrographs of a cavity and its surface created by the laser at normal incidence. (E to H) Optical tomographic images of cavities created by the laser at incident angles of (E) 0°, (F) 10°, (G) 20°, and (H) 30°. The diameter of each field of view is 200 μm.

  • Fig. 4 Ultrasound spectra and propagation pathways.

    (A) Representative ultrasound traces (inset) without and with jets. (B) FFT spectrum of the ultrasound in (A). a.u., arbitrary units. Inset is the enlarged time domain traces from (A). (C) Ultrasounds in different configurations. Green, laser pulse. Ultrasound traces in (out of laser focus) black and (near focus) red are from configuration 1 without streaming. Trace in blue is from configuration 2 with streaming. Purple trace is from configuration 3 with streaming. (D) Laser power–dependent ultrasound signals. Trace in red uses configuration 2 in (C), and the rest use configuration 3 in (C). The size of the cuvette in (A) to (D) is 1.5 cm × 1.5 cm.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/9/e1700555/DC1

    fig. S1. Comparison of flows generated by Au nanoparticles with different sizes.

    fig. S2. Flows generated by Au nanorods.

    fig. S3. No laser streaming with Ag nanoparticles.

    fig. S4. Comparison of flows with different particle concentrations.

    fig. S5. Streaming with different laser focus conditions.

    fig. S6. Streaming with 50-nm Au film on glass in pure water.

    fig. S7. Lifetime of streaming in pure water.

    movie S1. Streaming and flow pattern.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Comparison of flows generated by Au nanoparticles with different sizes.
    • fig. S2. Flows generated by Au nanorods.
    • fig. S3. No laser streaming with Ag nanoparticles.
    • fig. S4. Comparison of flows with different particle concentrations.
    • fig. S5. Streaming with different laser focus conditions.
    • fig. S6. Streaming with 50-nm Au film on glass in pure water.
    • fig. S7. Lifetime of streaming in pure water.
    • Legend for movie S1

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    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.mov format). Streaming and flow pattern.

    Files in this Data Supplement: