| 摘要 |
FIELD: system for protecting valuables composed of surface parts with relief structure causing optical diffraction. SUBSTANCE: protective member, in particular, visually identified optical member for protecting valuables, such as documents, banknotes, credit cards, certificates and other objects, has surface parts provided with at least two portions having similar relief structures offset one with respect to another by value equal to part of grid interval. Surface portions have maximum size exceeding 0.3 mm and relief structure mating with regard to space frequency, section shape and orientation and height difference. Mentioned at least two portions have minimum size of 0.3 mm. Such construction allows surface portion brightness to be modulated without using relief structures differing one from another. EFFECT: increased efficiency, simplified construction and enhanced reliability in operation. 8 cl, 6 dwg |
