Verification Method
The present invention relates to a verification method of tablets, in particular pharmaceutical tablets. It further relates to an invisible secure marking or information which is a part of such tablet. The invention further relates to tablets suitable for such verification method, to processes for manufacturing such tablets and methods for reading the information.
1 . A tablet, comprising one or more predetermined three-dimensional structures on its surface or below a coating wherein said predetermined structures are >2 um in lateral direction and >50 nm in vertical direction and wherein said structures are invisible to the unaided eye and wherein said structures are detectable by an optical detection device, in particular by optical interferometry microscopy.
2 . A tablet according to claim 1 comprising one or more predetermined three-dimensional structures on its surface wherein said predetermined structures are 2 um to 50 um in lateral direction and 50 nm to 5 um in vertical direction.
3 . A tablet according to claim 1 comprising a core, a coating and one or more predetermined three-dimensional structures at an interface between core and coating wherein said structure is invisible to the unaided eye through the coating.
4 . A tablet according to claim 3 wherein the index of refraction of the coating and the index of refraction of the core differs by at least 0.04 (real part) and/or by 0.02 (imaginary part).
5 . A tablet according to claim 1 which is a pharmaceutical tablet.
6 . A verification method for a tablet, in particular a pharmaceutical tablet, wherein said tablet comprises one or more three-dimensional structures on its surface or below a coating, wherein said structure is invisible to the unaided eye and wherein said method comprises the step of detecting said structure by means of an optical detection device.
7 . The verification method according to claim 6 comprising the steps of recording a data set by means of said detection device, wherein said data set describes characteristics of said structure and comparing the thus obtained data set with at least one predefined data set.
8 . The verification method according to claim 7 , wherein said structure was obtained by an embossing method using an embossing tool, wherein said predefined data set comprises characteristics of an embossing surface of said embossing tool, and in particular wherein a plurality of predefined data sets is provided, each comprising characteristics of one of a plurality of embossing tools.
9 . The verification method according to claim 6 wherein said detection device comprises an optical interferometry microscope.
10 . The verification method according to claim 9 wherein the detection device is an optical coherence tomograph, in particular a parallel optical coherence tomograph.
11 . The verification method according to claim 6 wherein the tablet comprises a pharmaceutical tablet.
12 . The verification method according to claim 6 wherein said tablet comprises a core and a coating and wherein said structure, in particular said predetermined structure, is located at an interface between said core and said coating and wherein said method comprises the step of detecting said structure through said coating.
13 . The verification method according to claim 6 wherein said tablet is located in a blister.
14 . The verification method according to claim 6 wherein the tablet is a pharmaceutical tablet.
15 . A method of use of optical interferometry microscopy for verification of tablets, in particular for a tablet according to claim 1 .
16 . A process for manufacturing a tablet according to claim 1 comprising the step of embossing one or more of said predetermined structures on the surface of said tablet and optionally coating said tablet.