SBIR Phase I: Low-Cost Laser Ultrasonic Receiver for Industrial Inspection Based on Pseudo Phase Conjugation

This Small Business Innovative Research (SBIR)Phase I project proposes to demonstrate the feasibility of using a passive, interferometric receiver using pseudo phase conjugation as part of a low-cost laser ultrasonic inspection system for industrial inspection and process control. In many industrial applications, conventional nondestructive inspection techniques cannot be applied for real-time process control, because parts are hot, vibrating or translating rapidly. Laser ultrasonics is a remote, non-contact inspection technique that overcomes these limitations and can function in the most demanding industrialenvironments. The new receiver will demonstrate high detection sensitivity and bandwidth, as well as static and dynamic compensation for speckles from rough surfaces. The design is adapted from classical concepts but requires no path-length stabilization and uses no photo-refractive crystal. The receiver can operate at an eye-safe wavelength using fiber optic components developed for telecomm applications. Laser ultrasonics can be used for in-line wall thickness measurement of seamless steel tubes and glass containers, for in-line inspection of laser welds, and scanning inspection of large composite panels used in the aerospace industry. Substantial cost savings have been documented in each case.