Optical properties and Monte Carlo simulation of cotton fibers with different micronaire values

Micronaire is a comprehensive index that characterizes the maturity and fineness of cotton fibers, an important quality parameter. Spectroscopic techniques have great potential to evaluate the micronaire, allowing for more accurate predictions by measuring cotton fibers' optical properties. In this study, the optical properties of cotton fibers with different micronaire values were tested, and photon interactions with cotton fibers were explored using Monte Carlo (MC) simulations. The absorption coefficient ( μ a ) and scattering coefficient ( μ s ) of cotton fibers were obtained in the 400–1100 nm range using a single integrating sphere-based system and the inverse adding doubling (IAD) method. Relationships between the micronaire and the total reflectance, total transmittance, μ a , μ s , and full attenuation coefficients ( μ t ) were analyzed using the Pearson correlation coefficients. Feature bands were selected using competitive adaptive reweighted sampling (CARS), and regression prediction models of the optical parameters and the micronaire were established for both full and feature bands. MC models simulated the effects of thicknesses (3 mm, 5 mm, 7 mm, and 9 mm) on diffuse reflectance, transmittance, and absorbed fraction. The results showed that micronaire strongly correlated with total reflectance, total transmittance, μ s , and μ t , with R² values of 0.88, 0.85, 0.91, and 0.92, respectively. MC simulations indicated that as sample thickness increased, diffuse reflectance increased. Thinner samples with 3 or 5 mm width combined with reflection or scattering properties on the feature bands could improve detection efficiency. These findings support the development of rapid nondestructive testing equipment for cotton fiber micronaire. • Obtaining optical properties of cotton fibers using an integrating sphere-based system combined with the inverse adding doubling algorithm. • Prediction of cotton fiber micronaire using optical property parameters in the full and feature bands respectively in the range 400–1100 nm. • Monte Carlo simulation of light interacting with cotton fibers at different thicknesses. • Power density distribution of cotton fibers using min-max optical properties with different thicknesses.