Non-destructive Evaluation of Polarization in Sugarcane Stalk Using Near Infrared Hyper Spectral Imaging

Abstract

Near-infrared spectroscopy can be applied to assess polarization (Pol) non-destructively. It can reduce the analysis time compared to conventional methods in the laboratory.  However, assessment by near-infrared spectroscopy is a spot measurement on the sugarcane, not covering the surface of the sample. This research applied non-destructive quality analysis using near-infrared hyper spectral imaging technique that can cover the whole surface in scanning to create an image to evaluate the Pol value on the plane area of sugarcane surface. This is an advantage compared to near-infrared spectroscopy techniques. In the study, 300 sugarcane stalks of cultivar Khon Kaen 3 used were harvested at age between 8-11 months from Suphan Buri province. The Pol values of the samples were in the range of 4.93-23.38%. The absorbance of each stalk was measured for in the range of 900-1700 nm. Each cane sample was scanned and measured by placing it on a translational moving platform which conveyed the samples past under the absorbance recording camera of the near-infrared hyperspectral system. The partial least squares regression technique was used to create a Pol prediction equation by studying the effects of wax on the surface of sugarcane. The results showed that the optimal models developed from surface-cleaned sugarcane samples provided the best predictive performance. The determination coefficient was 0.83 and the standard error of prediction was 1.52%. When using the best equation to predict the Pol value of each pixel of the hyperspectral image to create color-mapped image, the color-mapped image visually showed the polarization distribution map with corresponding color over the plane area of the stalk surface. The pol color mapped image revealed that sugarcane at the bottom of the stem had higher Pol value than cane at the top of the stem. The results of this study demonstrated the potential of near-infrared hyperspectral imaging techniques for the future development of fast and non-destructive polarization probes.