Patent ID: 6128081
Filing Date: 2000-10-03
Classification: G01B,G01N

Abstract:
A method for measuring a physical parameter of at least one layer of a multilayer article without damaging the article, the method comprising the steps of:generating a first pulse of electromagnetic energy;transmitting the first pulse to a sensing station;generating a second pulse of electromagnetic energy;transmitting the second pulse to the sensing station;directing the first pulse at the sensing station toward a first spot on a surface of the article to generate an ultrasonic wave in the article which, in turn, causes ultrasonic motion of the surface of the article without damaging the article;directing the second pulse at the sensing station toward a second spot on the surface of the article which substantially overlaps the first spot to obtain a reflected pulse of electromagnetic energy which is modulated based on the ultrasonic motion of the surface;transmitting the reflected pulse from the sensing station;detecting the reflected pulse after the step of transmitting the reflected pulse to obtain a corresponding ultrasonic electrical signal; andprocessing the ultrasonic electrical signal to obtain a physical parameter signal which represents the physical parameter of the at least one layer at the first and second substantially overlapping spots.