Thickness measurement of tablet coating using continuous-wave terahertz reflection spectroscopy

Nirmala Devi; Jyotirmayee Dash; Shaumik Ray; Bala Pesala

doi:10.1117/12.2212366

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25 February 2016 Thickness measurement of tablet coating using continuous-wave terahertz reflection spectroscopy

Nirmala Devi, Jyotirmayee Dash, Shaumik Ray, Bala Pesala

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Proceedings Volume 9747, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX; 974709 (2016) https://doi.org/10.1117/12.2212366
Event: SPIE OPTO, 2016, San Francisco, California, United States

Abstract

THz rays have higher penetration depth compared to infrared rays and hence can be effectively used to measure tablet coating thickness. In addition, THz wavelength (1 mm - 0.1 mm) provides an optimal depth resolution for the thickness measurement. This method can be non-invasive and hence ideal for inline quality monitoring. Tablet coating thickness is one of the major parameters of interest in Process Analytical Technology (PAT). In this paper, a reflection mode Continuous Wave (CW) Terahertz (THz) system has been employed to measure the tablet coating thickness. A frequency scan of the sample has been carried out from 0.1 THz to 1.1 THz and the reflection coefficient of the sample is inverse fourier transformed to obtain the tablet thickness. The calculated thickness has also been validated using the optical microscope. Results show that the thickness can be measured with considerable accuracy.

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Nirmala Devi, Jyotirmayee Dash, Shaumik Ray, and Bala Pesala "Thickness measurement of tablet coating using continuous-wave terahertz reflection spectroscopy", Proc. SPIE 9747, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX, 974709 (25 February 2016); https://doi.org/10.1117/12.2212366

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