| 摘要 |
Device and method for inspecting a polychromatic region, such as a polychromatic pattern, on a moving workpiece. The method includes device includes a solid-state light source, preferably a light emitting diode, adapted to emit light in a range of wavelengths for illuminating the polychromatic region. Photodetectors are positioned relative to the workpiece to intercept light from the light source reflected by the polychromatic region. Each of the photodetectors is adapted to detect reflected light within a corresponding one of a plurality of bands defined within the range of wavelengths. The method includes detecting intensities of the light reflected from the polychromatic region within different wavelength bands in the range of wavelengths and evaluating a ratio of the intensities for comparison with a standard ratio to ascertain a variation in the evaluated ratio.
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