Patent ID: 7507963
Filing Date: 2009-03-24
Classification: G01N

Abstract:
1. A method of evaluating the characteristics of a sample comprising the steps of: generating a submillimeter wave frequency optical radiation signal beam; generating a submillimeter wave frequency optical radiation reference beam, said reference beam having a frequency different from the signal beam; splitting the signal beam into first and second portions and directing the first portion of the beam to interact with the sample; splitting the reference beam into first and second portions; mixing the first portion of the signal beam that has interacted with the sample with the first potion of the reference beam to create a measurement intermediate frequency signal; mixing the second portion of the signal beam and the second portion of the reference beam to create a reference intermediate frequency signal; and processing the measurement and reference intermediate frequency signals in order to evaluate the sample based on changes to the signal beam induced by the interaction with the sample.