Directional Characteristics of near Infrared Light in the Process of Radiation and Transmission from Wood

Abstract

In this report, a newly designed apparatus, that is, a near infrared auto-goniophotometer, was introduced to acquire detailed optical information about biological material having a cellular structure like wood. Such information allows us to analyse the three-dimensional physical condition of a sample and confirm the suitability of proposed optical models. The directional characteristics could be found on the basis of the intensity of reflected or transmitted light at each observation angle. In these experiments, Sitka spruce ( Picea sitchensis Carr.) with various thicknesses were used. Results of these measurements showed the directional characteristics which were affected significantly by the illumination conditions and sample thickness. Particularly, these varied characteristically with the wavelength of the incident light. This result supports the validity of the proposed optical models which vary with wavelength. Throughout these analyses, the relationships between the physical aspects of a sample and the emitted light from it is being clarified.