Introduction
We present the first use of a widely tuneable, all-optical THz source (an intra-cavity parametric laser) for the thickness measurement of test objects. The optical thickness variation of a test target was measured in a Mach-Zehnder interferometer to within 0.5% of the THz wavelength, and wavelength tuning enabled the unambiguous measurement range to be extended to several wavelengths (half the synthetic wavelength). By detecting the phase change at different regions of an object, the system can also be used internal inspection of suitable materials that are opaque at visible wavelengths.
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Nguyen, TD., Valera, J.D., Moore, A.J. (2014). Thickness Measurement with Multi-wavelength THz Interferometry. In: Osten, W. (eds) Fringe 2013. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-36359-7_160
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DOI: https://doi.org/10.1007/978-3-642-36359-7_160
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-36358-0
Online ISBN: 978-3-642-36359-7
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