Abstract

Nondestructive measurements, based on NIRS (near-infrared spectroscopy), on biological material having cellular structure, such as wood, require a nontraditional approach. In this respect, a truly nondestructive measurement system that can accurately monitor the physical condition and chemical components of materials is very desirable. Supported by a series of experiments, we constructed optical characteristic concepts that account for the cellular structure of a sample. The system was successfully modeled by following theoretically the sequential propagation of light in a sample (specifically, scattering, reflection, absorption, and transmission), which varies according to the angle of the fibers with respect to the direction of incident light, theta, and with its wavelength. A set of optical models, which consists of a directional characteristics model and a light-path model, has been developed to describe the various steps in the sequence. On the basis of these models, the leakage ratios of diffusely reflected light from the aggregate width of semi-infinite tracheids, S(theta), for various conditions of irradiation were calculated. These values were in good agreement with the actual values obtained from the measured values of absorbance through the judicious use of a semi-theoretical equation.

Determination of true optical absorption and scattering coefficient of wooden cell wall substance by time-of-flight near infrared spectroscopy

Ryunosuke Kitamura, Tetsuya Inagaki, and Satoru Tsuchikawa
Opt. Express 24(4) 3999-4009 (2016)

Optical properties of drying wood studied by time-resolved near-infrared spectroscopy

Keiji Konagaya, Tetsuya Inagaki, Ryunosuke Kitamura, and Satoru Tsuchikawa
Opt. Express 24(9) 9561-9573 (2016)

Light propagation in dry and wet softwood

Alwin Kienle, Cosimo D’Andrea, Florian Foschum, Paola Taroni, and Antonio Pifferi
Opt. Express 16(13) 9895-9906 (2008)

Mathematical proof of an extended Kirchhoff law for a cavity having direction-dependent characteristics

Y. Ohwada
J. Opt. Soc. Am. A 5(1) 141-145 (1988)

Correlating light scattering with internal cellular structures

Oana C. Marina, Claire K. Sanders, and Judith R. Mourant
Biomed. Opt. Express 3(2) 296-312 (2012)