LASER OPTICAL DETECTION OF ELASTIC WAVES PROPAGATION IN METALLIC PLATES

AN IMPROVED LASER GENERATION AND DETECTION SYSTEM UTILIZING FIBER OPTIC COUPLING TO THE INSPECTION SURFACE IS PROPOSED. THE SYSTEM USES ADVANCED INTERFEROMETER CONCEPTS AND TAKES ADVANTAGE OF THE REMOTE TRANSMISSION CAPABILITIES OF THE FIBER OPTICS TO PROVIDE IMPROVED SIGNAL-TO-NOISE CAPABILITIES IN THE MANUFACTURING ENVIRONMENT. THE SYSTEM WILL OFFER EXCEPTIONAL CONTROL OF SOUND INPUT AND DETECTION AREA AND LOCATION SUCH THAT MATERIALS CHARACTERIZATION AS WELL AS FLAW DETECTION WILL BE POSSIBLE. THE SYSTEM WILL BE DEVELOPED FOR THE INSPECTION OF METALLIC MATRIX MATERIALS, BUT SHOULD BE APPLICABLE TO MANY INSPECTION APPLICATIONS REQUIRING NONCONTACT GENERATION AND SENSING. A MAJOR OBJECTIVE OF THE PHASE I EFFORT WILL BE THE CHARACTERIZATION OF THE EFFECTS OF SURFACE ROUGHNESS AND EXTERNAL NOISE AND VIBRATION ON THE SIGNAL-TO-NOISE CHARACTERISTICS AND SENSITIVITY OF THE LASER BASED SYSTEMS. SYSTEM VARIABLES TO BE EVALUATED WILL INCLUDE INTERFEROMETER TYPE, LASER SOURCE TYPE AND POWER. THIS FEASIBILITY STUDY WILL LEAD TO THE DEVELOPMENT OF A USEFUL SYSTEM TO INSPECT ADVANCED MATERIALS IN-SITU. COMMERCIAL PROSPECTS CLEARLY EXIST FOR AN EFFECTIVE NONCONTACT INSPECTION SYSTEM SUITABLE FOR THE PRODUCTION ENVIRONMENT.