Patent ID: 7512518
Filing Date: 2009-03-31
Classification: G01B

Abstract:
1. A method for determining a thickness of a layer in a multi-layered body comprising: selecting a body comprising a first layer having a lower surface and a second layer having an upper surface in contact with the lower surface of the first layer via a third layer forming a first interface with the lower surface of the first layer and a second interface with the upper surface of the second layer; applying a wave to the body that will cause a primary echo to be reflected from the first interface and a secondary echo to be reflected from the second interface; detecting and digitizing the primary echo and the secondary echo to generate a digital time series containing both of the echoes; constructing a numerical function with intrinsic arguments that are the digital time series, primary and secondary echo models, and extrinsic arguments that are the time location and amplitude of the primary echo and secondary echo, in addition to other optional extrinsic arguments, to generate a function used to quantify a goodness of fit of the primary and secondary echo models, wherein the primary and secondary echo models are generated by: maximizing the goodness of fit as quantified by the numerical function with respect to the extrinsic arguments or the optional extrinsic arguments; determining a flight time in the third layer from a difference between the time locations of the primary and secondary echoes, and determining a thickness of the third layer of the body which is equal to one half of the determined flight time multiplied by the velocity of the wave in the third layer.