Patent ID: 8400166

Claim:
A method, comprising: directing electromagnetic energy toward an article under test; taking measurements of electromagnetic energy scattered by the article under test; determining expected baseline values of at least one electromagnetic property of the article under test, wherein the expected baseline values are determined based on measurements of electromagnetic energy scattered by a control article; determining a difference between the expected baseline values and characteristic values of the article under test, wherein the characteristic values of the article under test are determined based on measurements of electromagnetic energy scattered by the article under test; and determining output data based on the determined difference between the expected baseline values and the characteristic values of the article under test, wherein the output data includes values that indicate a distribution of the at least one electromagnetic property of the article under test, and wherein the output data is determined using a distorted wave Born approximation and singular value decomposition to estimate values of an electromagnetic field internal to the article under test based on the measurements of the electromagnetic energy scattered by the article under test.