Abstract: Method and apparatus for validating banknotes. In some countries, genuine banknotes are provided with a security thread embedded in the banknote, but partially exposes at regularly spaced regions along its length by windows. The windows have a width greater that the security strip itself. The increased transmissivity of the banknote in the infrared region is utilized to detect the presence of such windows to validate the banknote. If the required variation in transmissivity is not detected, the banknote can be rejected as a countefeit.

Abstract: A profile sensor apparatus and method for measuring the contours and/or the thickness of a document or other thin sheet material is disclosed. In one embodiment, a planar beam assembly has a roller wheel attached to a first end and a mounting brace attached to a second end. The planar beam assembly includes at least one strain sensor and a flexible substrate, wherein the substrate may be coated with a visco-elastic polymer layer for damping any resonant vibrations which may occur during operation. A hard reference surface is located opposite the roller wheel. A mechanical preload biases the roller wheel to contact the reference surface with a predetermined amount of force to ensure correct operation. As a document passes between the reference surface and roller wheel, the roller wheel is displaced which in turn causes the planar beam assembly to flex. As the planar beam assembly deforms the strain sensor generates electrical signals which are proportional to the profile and/or the thickness of the document.