Imaging and quantitative analysis of water evaporation process using spectral-domain optical coherence tomography under illumination with two near-infrared wavelengths

Observation of viscous liquid flow in tobacco substrate during heating using optical coherence tomography

“…The absorption coefficient of glycerol at 1470 nm wavelength is 10.113 cm −1 [39]. Makino et al [14] used SD-OCT with two near infrared (NIR) wavelengths to see the evaporation process of water from the porous tobacco substrate under ambient conditions. They noted that the presence of water in the pores of the medium darkens the appearance of the tomographic image due to refractive index matching.…”

“…10: 230150 contrary. In previous research [14], the movement of liquid water in porous tobacco substrate under ambient condition has been successfully quantified by the attenuation coefficient.…”

“…A high attenuation coefficient represents high backscattering intensity while a low attenuation coefficient represents the contrary. In previous research [ 14 ], the movement of liquid water in porous tobacco substrate under ambient condition has been successfully quantified by the attenuation coefficient.…”

“…To help visualize liquid transmission in multilayered planes, previous studies have proposed methods such as X-ray-computed tomography [8], micro-CT [9], nuclear magnetic resonance (NMR) [10], digital camera-based light reflection measurement [11], light transmission and impedance spectroscopy [3], a micro-model (a representation of a porous medium) combined with confocal laser scan microscopy [12], and optical coherence tomography (OCT) [13][14][15][16]. X-ray and micro-CT offer non-destructive visualization of liquid flow in porous media, such as smart textiles [8] and powder beds [9], with a spatial resolution of around 5-150 µm [17].…”

“…OCT can reach a penetration depth of up to 1 mm with a resolution of up to 1 µm [ 18 ]. In previous studies, OCT has been used to monitor viscous liquid sorption into paper [ 13 ], drying of colloid droplets [ 15 , 16 ] and evaporation of water from porous tobacco layers/substrates [ 14 ]. To the best of our knowledge, all studies on liquid flow using OCT technique were conducted under ambient conditions.…”