Comparison of different types of light sources for optical cotton mass measurement

The property of attenuation of light by cotton fiber is used for estimation of cotton fiber mass in cotton classification using high-volume instrument s (HVIs). The objective of this study was to determine the light source typ es that have the best attenuation characteristics for the purpose of cotton fiber mass measurement leading to its use in HVI systems. The effect of di fferent varieties and moisture content levels on the relationship between a ttenuation and cotton fiber mass was also studied. Attenuation values for d ifferent amounts of cotton were measured for three different cotton varieti es at three different moisture content levels (low, medium, and high) by us ing an attenuation measurement system fabricated for this study. Seven type s of light source (two ultraviolets, halogen, red light-emitting diode, two lasers, and near infrared) at different wavelengths against seven differen t cotton mass density levels were tested with three replications. The study showed that the relationship between cotton fiber mass density an d the attenuation was nonlinear for all of the sources tested in the study. The effects of the variety and moisture content level were found to be ins ignificant only for the red LED and near infrared (NIR) sources. The NIR so urce has the widest attenuation range and was not affected by different var ieties and moisture content levels. The cotton fiber mass density can be es timated from the percent attenuation of NIR using a single calibration equa tion (R-2 = 0.9709) for different varieties and moisture content levels wit h reasonable accuracy.