Design of a camera-based reflectance measurement system with RGB LED illumination

Abstract

Reflectance spectroscopy is a nondestructive technique that analyzes the characteristics of a material by measuring the intensity of light it reflects across different wavelengths of the electromagnetic spectrum. This study presents the design and development of a camera-based reflectance measurement system using RGB LED illumination controlled by an Arduino UNO. The reflectance across various fruit samples was determined using open-source software, Theremino, and compared to reference wavelengths measured in a laboratory-grade spectropohotometer. Different slit sizes were also tested to determine the optimal slit size for reflectance measurements. Results showed that the 8-mm slit for the system produced better wavelength accuracy and peak alignment, offering more reliable and consistent results. In contrast, the 17-mm slit may also be useful in applications where enhanced signal strength is of greater importance. This study highlights the importance of slit selection and normalization methods when comparing homemade spectrometry systems with calibrated commercial instruments.