Teraview Limited

Daniel James Farrell

Ian Stephen Gregory

Robert May

A method for determining the thickness of a plurality of coating layers. The method comprises the steps of performing a calibration analysis on calibration data to determine initial values and search limits of optical parameters of the plurality of coating layers, irradiating the plurality of layers with a pulse of THz radiation in the range from 0.01 THz to 10 THz, detecting the reflected radiation to produce a sample response derived from the reflected radiation, producing a synthesized waveform using the optical parameters and predetermined initial thicknesses of the layers, varying the thicknesses and the optical parameters within the search limits to minimize the error measured between the sample response and the synthesized waveform, and outputting the thicknesses of the layers.

Method and system for measuring coating thickness

A method for determining the thickness of a plurality of coating layers, the method comprising: performing a calibration analysis on calibration data to determine initial values and search limits of optical parameters of said plurality of coating layers, irradiating the said plurality of layers with a pulse of THz radiation, said pulse comprising a plurality of frequencies in the range from 0.01 THz to 10 THz; detecting the reflected radiation to produce a sample response said sample response being derived from the reflected radiation; producing a synthesised waveform using the optical parameters and predetermined initial thicknesses of said layers; and varying said thicknesses and varying said optical parameters within the said search limits to minimise the error measured between the sample response and the synthesised waveform; and outputting the thicknesses of the layers.

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Cambridge, United Kingdom

Daniel James Farrell