Non-destructive quantification of pharmaceutical tablet coatings using terahertz pulsed imaging and optical coherence tomography
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Optical coherence tomography (OCT) and terahertz pulsed imaging (TPI) are two powerful techniques allowing high quality cross-sectional images from within scattering media to be obtained non-destructively. In this paper, we report experimental results of using OCT and TPI for quantitatively characterizing pharmaceutical tablet coatings in the thickness range of 10140 μm. We found that the spectral OCT system developed in-house has an axial resolution of 0.9 μm, and is capable of quantifying very thin coatings in the range of 1060 μm. The upper limit of 60 μm within the tablet coating and core is owed to the strong scattering of OCT light, which has relatively short wavelengths in the range of 0.51.0 μm. On the other hand, TPI utilizes terahertz radiation that has substantially long wavelengths in the range of hundreds of microns, and thus is less prone to the scattering problem. Consequently TPI has been demonstrated to be able to quantify thicker coatings in the range of 40140 μm and beyond. We concluded that OCT and TPI are two complementary analytical techniques for non-destructive and quantitative characterization of pharmaceutical tablet coatings.
|Journal||Optics and Lasers in Engineering|
|Number of pages||5|
|Publication status||Published - Mar 2011|
The authors would like to acknowledge the financial support from UK Technology Strategy Board ( AB293H ). S. Zhong would like to thank Fuzhou University Research Fund, Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, P.R. China, and National Natural Science Foundation of China ( 51005077 ).
- Non-destructive testing, Optical coherence tomography, Tablet coating thickness, Terahertz pulsed imaging