Patent ID: 6324004
Filing Date: 2001-11-27
Classification: B42D,G02B,G06K,Y10S

Abstract:
A surface pattern comprising elements arranged in a mosaic-like fashion and of which at least a background element and a pixel have microscopically fine diffraction gratings B diffracting visible light comprising a superimposition of at least two different relief structures F.sub.1, F.sub.2 and surface elements and element portions either contain the microscopically fine relief structures diffracting visible light or comprise reflecting or scattering surfaces, whereina first diffraction grating B.sub.B {F.sub.1, F.sub.2, .DELTA..phi..sub.B } is arranged in the pixel and a second diffraction grating B.sub.H {F.sub.1, F.sub.2, .DELTA..phi..sub.H)} is arranged in the background element,the diffraction gratings B.sub.B and B.sub.H each have a superimposed relief structure F.sub.1 +F.sub.2, wherein F.sub.1 is a first relief structure having the spatial frequency f.sub.1 and F.sub.2 is a second relief structure having the spatial frequency f.sub.2 and .DELTA..phi. is a relative phase shift of the second relief structure F.sub.2 with respect to the first relief structure F.sub.1 and the spatial frequency of the diffraction grating B.sub.B and that of the diffraction grating B.sub.H are equal to the lower of the two spatial frequencies f.sub.1 and f.sub.2the relationship V.sub.F of the second to the first spatial frequencies f.sub.2 /f.sub.1 is of a value from the range 1.5.ltoreq.V.sub.F.ltoreq.3,the grating vectors of the first diffraction grating B.sub.B in the pixel and the second diffraction grating B.sub.H in the background element as well as the grating vectors of the two relief structures F.sub.1, F.sub.2, are oriented in substantially parallel or anti-parallel relationship to a marked axis, andthe first diffraction grating B.sub.B and the second diffraction grating B.sub.H differ only by the relative phase shift .DELTA..phi. of the second relief structure F.sub.2 which is used for superimposition with the first relief structure F.sub.1.