Phase based Time Resolved Reflectance Spectroscopy using Time-of-Flight Camera for Fruit Quality Monitoring

Time-resolved phase-based reflectance spectroscopy has been used for the nondestructive assessment of the internal quality of the fruits in this work. The time taken by the incident light to backscatter and reach the detector placed at a distance from the camera relates to the penetration depth or mean free path of the light into the apples. The mean free path changes due to chemical pigmentation changes in apples during storage and ripening. Therefore, the scattering characteristics changes. The phase changes in the backscattered light are correlated to the stage of ripening or storage. The degree of linear polarization is used to quantify the changes in the reflected phase with increasing storage time. The proposed optical instrumentation is simple in construction and computationally less intensive and therefore, provides an affordable solution for a handheld compact fruit monitoring device.