SPECTRAL CONTENTS READOUT OF BIREFRINGENT SENSORS

A TRANSPARENT MATERIAL SUBJECTED TO STRESSES BECOMES BIREFRIGENT, PRODUCING A RELATIVE RETARDATION BETWEEN ORTHOGONALLY POLARIZED RAYS THAT IS PROPORTIONAL TO THE STRAINS. IN PHOTOELASTICITY, THIS RETARDATION IS MEASURED VISUALLY, USING A VARIETY OF COMPENSATORS, OR AUTOMATICALLY,USING COMPLEX ANALYZER ROTATORS OR ELECTRO-OPTICAL MODULATORS, LIMITED TO SMALL RETARDATION LEVELS. IN THE SPECTRAL CONTENTS APPROACH PROPOSED BY THIS RESEARCH,THE TRANSMITTED LIGHT INTENSITY IS MEASURED AT SEVERAL DISCRETE WAVELENGTHS, AND THE RESULTING SPECTRAL SIGNATURE IS INTERPRETED BY A MICROPROCESSOR IN TERMS OF THE MEASURED RETARDATION AND STRESS. THE RESULTING BIREFRINGENT SENSOR - SPECTRAL ANALYZER SYSTEMPERMITS A NONCONTACTING METHOD OF STRAIN MEASUREMENTS, WITH THE ABILITY OF CARRYING THE SIGNAL TO A REMOTE LOCATION, USING FIBER-OPTIC CABLES. THE PROPOSED RESEARCH EXTENDS THERANGE OF STRAIN MEASURMENTS TO HIGH TEMPERATURES.