| 摘要 |
The present invention provides an authentication apparatus operative to determine the authenticity of a polymer film, comprising an optically-based birefringence measuring arrangement operative to measure a first effect influenced by a birefringence characteristic of said film from a first angle comprising a non-normal angle to a plane of said film, and at least one of: a second angle; and a third angle; and wherein said apparatus is operative to: compare a value, or range of values, representative of said first effect as measured from said first angle with a value, or range of values representative of a specified first effect corresponding to a predetermined birefringence characteristic of an authentic polymer film for said first angle; compare a value, or range of values, representative of said first effect as measured from said at least one of said second and third angles with a value, or range of values representative of a specified first effect corresponding to a predetermined birefringence characteristic of an authentic polymer film for respective second and/or third angles; and output an authenticity signal indicative of authenticity or otherwise of said film based upon said comparisons. There are also provided one or more methods of determining the authenticity of a polymer film. |
