摘要 |
A technique which detects for the presence of particles or voids in material is disclosed herein. This technique utilizes an overall optics arrangement for producing a beam of radiation and for directing the latter into and through the material such that any void or foreign particle which is present causes the radiation impinging thereon to form an overall scattering pattern distinctly characteristic of whether the impinged void or foreign particle is generally spherical or non-spherical in shape. The technique disclosed herein also provides an arrangement for detecting scattered radiation, if any, and distinguishing between spherical and non-spherical foreign particles and, in a preferred embodiment, whether the impinged void/foreign particle is relatively large or small, relative to wavelength of said beam.
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