Abstract: Authentication apparatus (1, 100) and methods which authenticate an item (4, 110) responsive to the detection that a portion of the item has one or more predetermined characteristics, the said predetermined characteristics comprising either or both the thickness of the said portion of the item, and the thickness of one or more layers within the said portion of the item, determined by optically-based thickness measuring apparatus (6, 102-108). The item may be a product and the portion of the item may be a sheet of packaging material. The item may be a security document and the portion of the item may be a sheet of security document substrate.

Abstract: Authentication apparatus (1, 100) and methods which authenticate an item (4, 110) responsive to the detection that a portion of the item has one or more predetermined characteristics, the said predetermined characteristics comprising either or both the thickness of the said portion of the item, and the thickness of one or more layers within the said portion of the item, determined by optically-based thickness measuring apparatus (6, 102-108). The item may be a product and the portion of the item may be a sheet of packaging material. The item may be a security document and the portion of the item may be a sheet of security document substrate.

Abstract: Authentication apparatus (1, 100) and methods which authenticate an item (4, 110) responsive to the detection that a portion of the item has one or more predetermined characteristics, the said predetermined characteristics comprising either or both the thickness of the said portion of the item, and the thickness of one or more layers within the said portion of the item, determined by optically-based thickness measuring apparatus (6, 102-108). The item may be a product and the portion of the item may be a sheet of packaging material. The item may be a security document and the portion of the item may be a sheet of security document substrate.

Abstract: Authentication apparatus (1, 100) and methods which authenticate an item (4, 110) responsive to the detection that a portion of the item has one or more predetermined characteristics, the said predetermined characteristics comprising either or both the thickness of the said portion of the item, and the thickness of one or more layers within the said portion of the item, determined by optically-based thickness measuring apparatus (6, 102-108). The item may be a product and the portion of the item may be a sheet of packaging material. The item may be a security document and the portion of the item may be a sheet of security document substrate.

Abstract: A coating thickness gauge for measuring the thickness of a coating on a surface of a can is described. The gauge comprises a probe head and a probe head locating mechanism. By employing the probe head locating mechanism the probe head can be easily orientated relative to the surface of a can. The ability to select and fix the measurement orientation of the probe head provides the coating thickness gauge with enhanced flexibility such that it can be employed to take measurements from all surface sections of the can, both interior and exterior. This ability is not dependent on the experience, knowledge or skill of a particular operator. As a result the gauge provides for a fast means of measuring the thickness of a coating which can be used within an in line feedback system, on a commercial scale.