Patent DE-19908410-A1 (DE)
Title: Instrument to test the authenticity of an object has a heat ray unit and a sensor to register the reflected heat from the object surface for comparison with known reference values
Inventor: HERBST KLAUS
IPC: G01N25/72
Filed: 1999-02-26
Abstract: To test the authenticity of an object, it is heated by a heating source (7) at least in a zone, to a given temp. The reflected heat from the object is registered by a heat-sensitive detector (8), to be evaluated according to the physical temp. characteristics of the object.  The heating is an ultrasonic or eddy current generator, to heat the object by direct contact. Or it is a laser, an infra red or high frequency generator which is brought close to the object under test. The heating (7) is switched off as soon as the surface temp. of the object has reached a specific level of 100  deg C or below. The sensor (8) can register the spectrum or heat reflection from the object and convert it into a measurement signal to form a thermal image of the object surface with measurement stability. The sensor (8) is preferably. an infra red camera system, focused on to the object surface by a diaphragm or lens. The heating temp. of the object surface is determined by the maximums in the measured spectral distribution. The characteristic used for the object material is the heating capacity and/or thermal conductivity, verified by the geometric and time development of the heat radiation frequency over an area of the object surface. The spatial and/or time development of the heat radiation frequency is taken with reference to the image and/or time point of the max. measured heat radiation frequency, and is compared with a stored reference heat development pattern. The reference is formed from a number of measured heat development patterns of a number of identical objects each with a tolerance, to form an average value. The measured development pattern(s) and/or the declared tolerance from the object manufacturer are used to give a variable scatter or variation value to show the permissible variation of the readings from the stored reference value, and also give upper and lower threshold values. If the upper or lower threshold values are breached, the measurement shows that the object is not authentic, and is authentic if it lies within the thresholds.  An Independent claim is included for an instrument with a heat delivery unit (7), a heat radiation sensor (8), and an evaluation unit for the sensor signals. Preferred Features: The heat unit, close to the sensor (8), delivers a beam of laser light, or infra red or high frequency rays. The sensor (8) is an infra red sensor. The heat (7) and sensor (8) units are aligned for their electromagnetic or optical axes to intersect at a focus point on the object surface, at a gap of 5-20 cm from the instrument. A unit can be fitted to the front side of the instrument to set the gap from the focus point. The instrument has a memory to store the reference and/or threshold data. One or more comparators give a comparison by points of the measured heat development at the object surface with the stored reference or threshold development patterns. A signal triggers a display to show that the object is authentic or not. An input has keys to set and control the instrument functions. A monitor screen can display the functions and control menu, and a connector gives a data link to a data processing unit. The instrument (1) is within a portable housing (2) with a pistol grip (4) and a trigger button (5).