“…In contrast to the above mentioned techniques which measure particle size, Terahertz Pulsed Imaging (TPI) can be used to directly determine coating thickness as well as coating surface roughness. Most publications describe off-line use of TPI to determine coating thickness on pellets (Haaser et al, 2012) or tablets (Ho et al, 2009(Ho et al, , 2008(Ho et al, , 2007, although one publication also describes an in-line use of TPI to measure coating thickness during tablet film coating process (May et al, 2011).…”