Probing the nanoscale with high-speed interferometry of an impacting drop

Handle URI:
http://hdl.handle.net/10754/623646
Title:
Probing the nanoscale with high-speed interferometry of an impacting drop
Authors:
Thoroddsen, Sigurdur T. ( 0000-0001-6997-4311 ) ; Li, Erqiang ( 0000-0002-5003-0756 ) ; Vakarelski, Ivan Uriev ( 0000-0001-9244-9160 ) ; Langley, Kenneth ( 0000-0001-6999-8727 )
Abstract:
The simple phenomenon of a water drop falling onto a glass plate may seem like a trivial fluid mechanics problem. However, detailed imaging has shown that this process is highly complex and a small air-bubble is always entrapped under the drop when it makes contact with the solid. This bubble can interfere with the uniformity of spray coatings and degrade inkjet fabrication of displays etc. We will describe how we use high-speed interferometry at 5 million frames per second to understand the details of this process. As the impacting drop approaches the solid, the dynamics are characterized by a balance between the lubrication pressure in the thin air layer and the inertia of the bot-tom of the drop. This deforms the drop, forming a dimple at its bottom and making the drop touch the surface along a ring, thereby entrapping the air-layer, which is typically 1-3 mu m thick. This air-layer can be highly compressed and the deceleration of the bottom of the drop can be as large as 300,000 g. We describe how the thicknessevolution of the lubricating air-layer is extracted from following the interference fringes between frames. Two-color interferometry is also used to extract absolute layer thicknesses. Finally, we identify the effects of nanometric surface roughness on the first contact of the drop with the substrate. Here we need to resolve the 100 nm thickness changes occurring during 200 ns intervals, requiring these state of the art high-speed cameras. Surprisingly, we see a ring of micro-bubbles marking the first contact of the drop with the glass, only for microscope slides, which have a typical roughness of 20 nm, while such rings are absent for drop impacts onto molecularly smooth mica surfaces.
KAUST Department:
King Abdullah Univ. of Science and Technology (Saudi Arabia)
Citation:
Thoroddsen ST, Li EQ, Vakarelski IU, Langley K (2017) Probing the nanoscale with high-speed interferometry of an impacting drop . Selected Papers from the 31st International Congress on High-Speed Imaging and Photonics. Available: http://dx.doi.org/10.1117/12.2270068.
Publisher:
SPIE-Intl Soc Optical Eng
Journal:
Selected Papers from the 31st International Congress on High-Speed Imaging and Photonics
Conference/Event name:
31st International Congress on High-Speed Imaging and Photonics
Issue Date:
28-Feb-2017
DOI:
10.1117/12.2270068
Type:
Conference Paper
Additional Links:
http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2606319
Appears in Collections:
Conference Papers

Full metadata record

DC FieldValue Language
dc.contributor.authorThoroddsen, Sigurdur T.en
dc.contributor.authorLi, Erqiangen
dc.contributor.authorVakarelski, Ivan Urieven
dc.contributor.authorLangley, Kennethen
dc.date.accessioned2017-05-17T07:41:40Z-
dc.date.available2017-05-17T07:41:40Z-
dc.date.issued2017-02-28en
dc.identifier.citationThoroddsen ST, Li EQ, Vakarelski IU, Langley K (2017) Probing the nanoscale with high-speed interferometry of an impacting drop . Selected Papers from the 31st International Congress on High-Speed Imaging and Photonics. Available: http://dx.doi.org/10.1117/12.2270068.en
dc.identifier.doi10.1117/12.2270068en
dc.identifier.urihttp://hdl.handle.net/10754/623646-
dc.description.abstractThe simple phenomenon of a water drop falling onto a glass plate may seem like a trivial fluid mechanics problem. However, detailed imaging has shown that this process is highly complex and a small air-bubble is always entrapped under the drop when it makes contact with the solid. This bubble can interfere with the uniformity of spray coatings and degrade inkjet fabrication of displays etc. We will describe how we use high-speed interferometry at 5 million frames per second to understand the details of this process. As the impacting drop approaches the solid, the dynamics are characterized by a balance between the lubrication pressure in the thin air layer and the inertia of the bot-tom of the drop. This deforms the drop, forming a dimple at its bottom and making the drop touch the surface along a ring, thereby entrapping the air-layer, which is typically 1-3 mu m thick. This air-layer can be highly compressed and the deceleration of the bottom of the drop can be as large as 300,000 g. We describe how the thicknessevolution of the lubricating air-layer is extracted from following the interference fringes between frames. Two-color interferometry is also used to extract absolute layer thicknesses. Finally, we identify the effects of nanometric surface roughness on the first contact of the drop with the substrate. Here we need to resolve the 100 nm thickness changes occurring during 200 ns intervals, requiring these state of the art high-speed cameras. Surprisingly, we see a ring of micro-bubbles marking the first contact of the drop with the glass, only for microscope slides, which have a typical roughness of 20 nm, while such rings are absent for drop impacts onto molecularly smooth mica surfaces.en
dc.publisherSPIE-Intl Soc Optical Engen
dc.relation.urlhttp://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2606319en
dc.rightsCopyright 2017 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.en
dc.subjectHigh frame rateen
dc.subjectinterferometryen
dc.subjectdrop impacten
dc.subjectair filmsen
dc.titleProbing the nanoscale with high-speed interferometry of an impacting dropen
dc.typeConference Paperen
dc.contributor.departmentKing Abdullah Univ. of Science and Technology (Saudi Arabia)en
dc.identifier.journalSelected Papers from the 31st International Congress on High-Speed Imaging and Photonicsen
dc.conference.date2016-11-06 to 2016-11-10en
dc.conference.name31st International Congress on High-Speed Imaging and Photonicsen
dc.conference.locationOsaka, JPNen
dc.eprint.versionPost-printen
kaust.authorThoroddsen, Sigurdur T.en
kaust.authorLi, Erqiangen
kaust.authorVakarelski, Ivan Urieven
kaust.authorLangley, Kennethen
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