ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Three-filter colorimetry has been introduced in the DIII–D tokamak to measure in situ the growth and the erosion of transparent wall coatings (a-C/B:H) in the divertor region. Colorimetry uses the interference of light on a transparent layer to measure the film thickness. The colorimetry setup at DIII–D consists of a light source, a black and white camera, and a filter wheel equipped with three broadband color filters. A white light source illuminates the area of interest. A picture with each filter is recorded and digitized. Thus the interference color of a semitransparent layer is measured and the film thickness is computed using the formalism of thin film optics. Since color cameras are more sensitive to neutron damage, a set of three filters was chosen which best matches the responsivity of a radiation-hardened B/W camera. In fact, one infrared filter and two visible filters are used. The three 2D camera images obtained from rotating the three filters into the line of sight of the camera are used to produce a 2D image of the change in film thickness due to the high flux of particles and power incident on the film during a diverted discharge. In a first measurement, the technique was used to measure the growth of a boron film in situ in the DIII–D tokamak. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1146095
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