| 摘要 |
MEASURING A GAP BETWEEN A TUBE AND A FLOAT An apparatus or method determines the gap between an assembly of a tube and a cylindrical float located substantially concentric to the tube. An elliptically polarized light beam at the wavelength for which the materials of the tube and the gap are transparent or translucent is along an optical axis. The index of refraction of the tube and float materials are greater than the index of refraction of the gap material. Means translates and rotates the assembly along and about its longitudinal axis producing an illumination. A light filtering means along the optical axis beyond the assembly blocks light of the illumination reflected by the assembly and refracted by the tube, the gap between the tube, and the float and the float and transmits light of the illumination refracted by the tube and the gap between tube and float. Light detection means receives transmitted light and signals a signal processing means. The method has steps of transmitting the monochromatic beam of elliptically polarized light along the optical axis to the assembly, focusing the beam of light, translating and rotating the assembly through the light, producing an illumination, filtering the illumination by blocking illumination reflected by the assembly and refracted by the float, the tube and the gap between the tube and the float and transmitting the illumination refracted by the tube and the gap between the tube and the float.
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