Fare card explosive detection system and process

In a substrate reading system for processing a fare card, I.D. card, key card, airline boarding pass, passport and the like presented by a substrate bearer at a checkpoint for validation, said system including an automatic reader with substrate intake and return ports, and a substrate conveying mechanism defining a path of movement for said substrate from said intake port to said return port, the improvement comprising:

• an image capture/digitizer unit positioned along said path of movement generally adjacent said automatic reader and adapted to formulate a primary digitized image of said substrate;
• a rapid heating stage positioned along said path generally adjacent said image capture/digitizer unit and adapted to heat said substrate at least to a temperature level to cause explosive trace substance present on said substrate to achieve an energetic reaction imparting a char smudge signature to said substrate, yet without damaging said card;
• said substrate conveying mechanism adapted to move said substrate from said rapid heating stage to said image capture/digitizer unit for formulating a secondary digitized image of said substrate and said char smudge signature;
• an image subtractor stage interconnected with said image capture/digitizer unit and adapted to receive said primary and secondary digitized images from said image capture/digitizer unit;
• said image subtractor stage further adapted to subtract said primary digitized image of said substrate from said secondary digitized image to obtain a digitized resultant image;
• a computer processor unit interconnected to said image subtractor stage and adapted to receive and analyze said digitized resultant image to determine presence or absence of said char smudge signature;
• said processor unit further adapted to produce an output signal prompted by presence or absence of said char smudge signature;
• whereby said substrate is automatically examined at said checkpoint, the presence of any trace explosive signature thereon is detected, an automatic validation decision is reached relative to the presence of said signature, and an output signal controls passage of said substrate bearer.

A method of processing a substrate such as a fare card, key card, I.D. card, airline boarding pass, passport and the like so as to discern the presence thereon of trace explosive substance for determining passage or refusal of a substrate bearer through a controlled gateway, said method

• including the steps of:
• introducing said substrate to an automatic reader for validation;
• subsequently capturing a first image of said substrate;
• digitizing said first image to formulate a primary digitized image of said substrate;
• rapidly heating said substrate causing any present trace explosive particles to achieve an energetic reaction forming a char smudge signature on at least a portion of said substrate;
• capturing a second image of said substrate following said rapid heating;
• digitizing said second image to formulate a secondary digitized image of the substrate;
• electronically subtracting said primary digitized image of said substrate from said secondary digitized image of said substrate and obtaining a digitized resultant image;
• processing said digitized resultant image to discern presence of said char smudge signature;
• automatically transmitting an output signal to said controlled gateway directing refusal of gateway passage when char smudge signature is discerned as present and to permit passage when char smudge signature is not discerned as present;
• whereby a substrate in the form of a subway fare card, entry key card, airline boarding pass, passport and the like presented by its bearer for validation and gateway passage is automatically examined, the presence of any char evidence of trace explosive substance is detected, and the bearer is permitted passage or restrained.