| 摘要 |
The method involves placing the product 5 in a light beam 2 from a laser source 1. In the focal plane 7 of a lens 6 placed behind the product 5, the focused light 9 is separated from the unfocused light 10 which corresponds to that part of the beam diffracted by the elements 5' emerging from the surface of the product 5. The spatial distribution and intensity of the unfocused light 10, which are representative only of the elements 5' emerging from the surface of the product, are analysed. With advantage, the image of the emergent elements 5' only is reconstructed from the diffracted light, and the analysis is carried out in the corresponding image plane 12. Application particularly in the textile industry, especially in analysing the hairiness of threads. <IMAGE>
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