ASABE Technical Library - Abstract

Abstract. Spatial-frequency domain imaging, as a noninvasive and wide field-of-view optical imaging technique, offers great potential for optical properties measurement of agro-products. In this study, a laboratory-based spatial-frequency domain imaging system was designed and established. The system consisted of a digital projector based on a digital light processing (DLP) to generate structured light and illuminate target sample periodically. The remitted light was captured by a CCD camera with 1280×960 resolution. Optical absorption and scattering coefficients were calculated in a field of 100×100 pixel by nonlinear least-square fitting in MATLAB. Three wavelengths (460, 527, 630 nm) were used by the selection of bandpass filters in the system. Pear, apple, and potato, as typical agro-products, were measured by the SFDI system to obtain the optical properties. The results indicated that they were scattering dominant tissues. The reduced scattering coefficients were similar to the results reported in the published studies, while the absorption coefficients were much higher. Further study in this field was required to improve the measurement accuracy and refine the calculation model in the future.