Patent ID: 9404854
Filing Date: 2016-08-02
CPC Classification: G01N

Claim Text:
1. A method for non-invasively evaluating a substrate material comprising the steps of: substantially simultaneously directing a first input beam of radiation having a first frequency from a first optical source and a second input beam of radiation having a second frequency from a second optical source to a predetermined area on a substrate material surface, with the first frequency differing from the second frequency by a predetermined amount; mixing the first input beam and the second input beam at the substrate material surface; producing second order and third order output signals in the THz regime from the substrate material; directing the second order output signal to a second order output signal detector to receive the second order output signal from the substrate material; directing the third order output signal to a third order output signal detector to receive the third order output signal from the substrate material; and measuring at least one characteristic of the substrate material based on the second output signal and third output signal received by the second order output signal detector and the third order output signal detector.