| abstract |
Disclosed herein is an interferometric-based materialsnanalysis system (10) that employs a novel combination ofnlaser beam shaping and pointing techniques, the use of anlow cost, rugged, and compact diode laser (22) as andetection laser, and the use of signal processingntechniques that compensate for inherent instabilities andnshort-term drift in the diode laser. A matched filternprocessing technique is disclosed for processingninterferometrically-obtained data points from a targetnbeing analyzed. The matched filter technique is shown to benespecially useful for detecting and analyzing Lamb modesnwithin thin targets, such as a silicon wafer undergoing anrapid thermal processing cycle. Also disclosed is a methodnand apparatus for interferometrically monitoring a targetnto determine, in accordance with predetermined criteria, annoccurrence of a period of time that is optimum fornobtaining a data point. In response to detecting such anperiod an impulse source, such as an impulse laser (14), isntriggered to launch an elastic wave within the target sonthat a data point can be obtained. A plurality of datanpoints so obtained are subsequently processed, such as bynthe matched filter technique, to determine a property ofninterest of the target. The property of interest may be, bynexample, the temperature of the target or the metallurgicalnstatus of the target. |