Spectroscopic Evaluation of Epidermis‐Equivalent Phantom in Terahertz‐Frequency Region

Abstract

AbstractThe complex refractive index and reflectance of an epidermis‐equivalent phantom were evaluated in the terahertz‐frequency region. The complex refractive indices of the epidermis and the epidermis‐equivalent phantom, made using ultrapure water, mineral oil, glycerin fatty acid ester, and agar, were measured using a terahertz time‐domain spectrometer. The complex refractive indices of the epidermis and the epidermis‐equivalent phantom were in agreement. However, their mean reflectances had a difference of approximately 3%. The difference disappeared on adding surface roughness to the epidermis‐equivalent phantom. Thus, we found that roughness of the surface of the epidermis‐equivalent phantom was required to ensure a match of the reflectance of the phantom with that of the epidermis at frequencies from 0.2 THz to 0.6 THz.