TWO-DIMENSIONAL MICRO-MATRIX CODE READER FOR FLEXIBLE COMPUTER-INTEGRATED MANUFACTURING

IN THE PRODUCTION OF PHARMACEUTICALS, BOTH THE WORK PIECE AND THE PACKAGING ARE TOO SMALL FOR CONVENTIONAL BAR CODES. OF PARTICULAR IMPORTANCE IS THE USE OF AUTOMATIC IDENTIFICATION TO VERIFY THE CORRECT LABELING OF PHARMACEUTICALS. MISLABELING HAS BEEN A PERSISTENT SAFETY PROBLEM AND PRODUCTION LINES FOR LABELING ARE CLOSELY REGULATED AND INSPECTED BY THE FDA. ALSO, PRODUCERS OF SEMICONDUCTOR WAFERS, SEMICONDUCTOR CHIPS, AND PRINTED CIRCUIT BOARDS ARE CONSIDERING TWO-DIMENSIONAL CODES DUE TO LACK OF SPACE FOR THE AMOUNT OF DATA THAT NEEDS TO BE ENCODED. THE MOST RELIABLE, ACCURATE, AND FASTEST TECHNIQUE FOR READING 2-D CODES WOULD BE A SOLID-STATE SCANNING APPROACH. OF THE VARIOUS TECHNIQUES AVAILABLE, STRESS-OPTICS, USING AN IMPOSED STRESS IN PHOTOELASTIC MATERIALS, IS THE BEST FOR SMALL BEAMS AND FAST, PRECISE SCANNING THROUGH RELATIVELY SMALL SWEEP ANGLES. STRESS CAN PRODUCE A MUCH GREATER INDEX CHANGE IN SOME GLASSES THAN CAN AN ELECTRIC FIELD IN E-O MATERIALS AND RESPONSE RATES UP TO MHZ ARE POSSIBLE. ALSO, THE IMPOSITION OF A STRESS TO OPTICAL GLASS DOES NOT INCREASE ITS ALREADY LOW-LOSS, AND THE RESPONSE IS NON-DISPERSIVE. FINALLY, OPTICAL GLASSES ARE GENERALLY MORE RUGGED AND ENVIRONMENTALLY STABLE AND COST LESS THAN DO THE MATERIALS USED IN OTHER APPROACHES. THE MANUFACTURABILITY OF THE BASIC S-O SANDWICH IS STRAIGHTFORWARD WHICH WOULD MAKE IT SIGNIFICANTLY CHEAPER THAN EO EQUIVALENT DEVICES. THESE LAST TWO ADVANTAGES ARE CONSIDERED TO BE VERY IMPORTANT IN THE MATRIX CODE READER MARKET. THE ACCURACY AND MICRO-RADIAN RESOLUTION OF A 2-D STRESS-OPTIC SCANNER IS DEMONSTRATED.