FIELD: physics, optics.
SUBSTANCE: proposed element comprises first and second optically variable element including the first and second optically variable thin-film laminar interference devices. Note here that said the first and second optically variable thin-film laminar interference devices are located so that they can be viewed together. The band covered by second device 3rd and 4th lengths waves lies in the band covered by first device 1st and 2nd lengths waves. This allows determination of definite light incidence angle whereat peaks of k-order of reflection of said 1st and 2nd interference coincide. Said 1st and 2nd optically variable interference devices feature identical interference structures so that they display true spectral matching at said preset light incidence angle while at other angles they feature different spectra.
EFFECT: high degree of protection against counterfeit.
19 cl, 3 dwg
