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Title: Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a movingmore » target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [1] ;  [4] ;  [1] ;  [2] ;  [5] ;  [1] ;  [4] ;  [4] ;  [4]
  1. Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States)
  2. (Japan)
  3. (Korea, Republic of)
  4. (United States)
  5. Yokohama Research Laboratory, Hitachi, Ltd., Kanagawa 244-0817 (Japan)
Publication Date:
OSTI Identifier:
22303836
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 25; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONFIGURATION; CURRENTS; DEFECTS; DETECTION; DISPERSIONS; ELECTRIC BATTERIES; ELECTRIC UTILITIES; FILMS; GAS UTILITIES; INSPECTION; LASERS; LIGHT EMITTING DIODES; LITHIUM IONS; MAGNETIC DISKS; MANUFACTURING; PULSES; SOLAR CELLS; SURFACES; VISIBLE RADIATION