Authentication apparatus and method

An authentication apparatus operative to determine the authenticity of a polymer film, comprising:

• an optical response modifier operative to modify a first effect influenced by said birefringence characteristic of said film to a modified first effect;
• and an optically-based birefringence measuring arrangement operative to measure said modified first effect;
• and wherein said apparatus is operative to:
• compare a value, or range of values, representative of said modified first effect as measured with a value, or range of values representative of a specified first effect as modified by a same optical response modifier and corresponding to a predetermined birefringence characteristic of an authentic polymer film;
• and
• output an authenticity signal indicative of authenticity or otherwise of said film based upon said comparison.

A method of determining the authenticity of a polymer film, comprising:

• modifying a first effect influenced by said birefringence characteristic of said film to a modified first effect;
• measuring said modified first effect
• comparing a value, or range of values, representative of said modified first effect as measured with a value, or range of values representative of a specified first effect as modified by a same optical response modifier and corresponding to a predetermined birefringence characteristic of an authentic polymer film;
• and
• outputting an authenticity signal indicative of authenticity or otherwise of said film based upon said comparison.