Method of authenticating watermarked paper
AssigneesSecretary of State for Defence in her Britannic Majesty's Government of the United Kingdom of Great Britain & Northern Ireland of Defence, Evaluation Research Agency
InventorsMarc I J Beale, David R Dinn
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Abstract
A method of authenticating watermarked paper comprises the steps of transtly heating a first surface (50) of a watermarked sheet of paper (40) using a hot air source (22); forming a thermal image of the watermark (42) using a thermal imager (30); and analyzing the thermal image to determine whether or not the watermarked paper is authentic. The evolution of the thermal image with time is characteristic of the watermark and is dependent on the local thermal mass of the paper in the region of the watermark.
Claims12
A method of authenticating watermarked paper comprising the steps of:
- (i) changing the temperature of a first surface (50) of a region of the paper containing a watermark (42);
- (ii) measuring the region's temperature during the change of temperature;
- and
- (iii) analyzing the temperature measurements to determine the thermal response of the paper as a function of time and hence determine whether or not the watermarked paper is authentic.
A watermark authentication system for determining whether or not a sheet of paper includes an authentic watermark comprising:
- means (22) for changing the temperature of a region of the sheet of paper;
- means (30) for making temperature measurements of the region of the sheet of paper during the change of temperature;
- and means for analyzing the temperature measurements to determine the thermal response of the paper as a function of time, and hence determine whether the paper is authentic.
Dependencies are inferred from the claim text.