Patent ID: 6271921
Filing Date: 2001-08-07
Classification: G01N,Y10S

Abstract:
A non-destructive system for characterizing a sample, comprising:means for a generating a sequence of optical pump pulses having a characteristic frequency f.sub.1 and for directing the sequence of pump pulses to an area of the surface of the sample;means for generating a sequence of optical probe pulses having a characteristic frequency f.sub.2 and for directing the sequence of probe pulses to a same or different area of the surface of the sample, wherein f.sub.1 is not equal to f.sub.2 for continuously varying a delay between the generation of a pump pulse and the generation of a probe pulse; andmeans for measuring, at a rate given by one of (f.sub.1 -f.sub.2) or (f.sub.1 +f.sub.2), at least one transient response of the structure to the sequence of pump pulses by detecting a change in a characteristic of a reflected or transmitted portion of the sequence of probe pulses.