Method and apparatus for identifying a product

摘要

The present invention relates to a method and a corresponding apparatus for identifying a product (1) or information relating to the product (1). In the method, a concealed code on the product (1) is identified, wherein the code is given by a set of ellipsometric parameters, and the method comprises the following steps of: measuring ellipsometric variables for at least one defined point (8) on a surface (9) of the product (1), comparing the measured ellipsometric variables with at least one reference code, and determining a match between the measured ellipsometric variables and the reference code or one of the reference codes or determining a mismatch with each reference code.

主权项

1. A method for discriminating between an imitation of a product and an original of the product by using a hidden code and at least one reference code, the hidden code and the at least one reference code comprising at least a pair of values measured at:
a defined wavelength or a defined wavelength distribution of a light directed on the product, and at a defined angle of incidence α of the light, the light having the defined wavelength or the defined wavelength distribution, wherein the light is selected to comprise a wavelength between UV and NIR, the light being directed on the product; wherein the hidden code and the at least one reference code are given by a set of ellipsometric parameters which are measurable with an ellipsometer by a polarization-dependent intensity of the light after reflection by the surface at a given location, wherein the hidden code and the at least one reference code carried by the original of the product are hidden to the naked eye, wherein the set of ellipsometric parameters includes natural surface characteristics of at least a portion of the surface of the original of the product at the given location, wherein the set of ellipsometric parameters comprises a value Ψ and a value Δ, with Ψ being a quotient of two reflection coefficients measured for two different polarizations, and with Δ comprising a phase shift between reflected light components of these two different polarizations, the method comprising the following steps: providing a test product, wherein the test product is the imitation of the product or the original of the product; defining the wavelength or wavelength distribution of the test product; defining several angles of incidence α of the test product; providing the at least one reference code; measuring ellipsometric variables for at least one defined location on a surface of the product and at several defined angles of incidence α, comparing the measured ellipsometric variables with the at least one reference code, determining an agreement of the measured ellipsometric variables with the at least one reference code, or one of the at least one reference codes, or determining a non-agreement with each of the at least one reference codes,and
identifying the imitation of the original product by determining the non-agreement with each of the at least one reference codes.