THIS PROPOSAL ADDRESSES THE DIRECT MEASURMENT OF FREE SURFACE MECHANICAL SHEER WAVES WITH A NON-CONTACT LASER SENSOR.

THIS PROPOSAL ADDRESSES THE DIRECT MEASURMENT OF FREE SURFACE MECHANICAL SHEER WAVES WITH A NON-CONTACT LASER SENSOR. THE PROPOSED SENSOR UTILIZES A HETERODYNE, 2-FREQUENCY HENE LASER DEVELOPED BY OPTRA. A PROTOTYPE HAS BEEN TESTED AND HAS THE CAPABILITY OF MEASURING IN-PLANE VIBRATIONS WITH SENSITIVITIES EQUAL TO OR EXCEEDING THOSE OF THE BEST CONTACT VIBRATION SENSORS, WITH THE ADDED BENEFIT OF A FREQUENCY RESPONSE COVERING THE FULL RANGE FROM DC TO 50KHZ. IN ADDITION, THE SENSOR HAS THE INHERENT ADVANTAGE OF A HIGH DEGREE OF ORTHOGONALITY WHICH ENABLES THE REJECTION OF OUT-OF-PLANE VIBRATIONS WHICH MAY BE PRESENT SIMULTANEOUSLY ON THE SURFACE BEING MEASURED OR IMPOSED ON THE SENSOR ITSELF. THE SENSOR IS COMPACT AND CAN BE MADE WHOLLY PASSIVE AND REMOTE BY USING FIBER OPTICS. THE AIM OF THE PROPOSED RESEARCH IS TO DEVELOP AN OPTIMIZED SENSOR AND TO DEMONSTRATE ITS PERFORMANCE ON A SIMPLE STRUCTURE EXCITED TO HAVE SHEAR WAVES, WHILE AT THE SAME TIME THE SENSOR AND STRUCTURE ARE SUBJECTED TO OTHER VIBRATIONS.