Low-cost tunable light source using RGB-LED module for absorption spectroscope

This paper focused for possibility to use RGB-LED module as a tunable light source for absorption spectroscope. Nowadays, commercial instrument uses Xenon lamp with Monochromator to select a specific wavelength for tested some properties on a sample. This part is a core of performance in an instrument and it increase cost of an instrument. In this paper, RGB-LED module will replace for a part of Xenon lamp and Monochromator to select a specific wavelength for measurement absorption or transmission properties. By used Arduino controller with pulse-width modulation method (PWM), a specific wavelength can control by mixed light that emitted from RGB-LED module. Resolution from this method can tuned an optical wavelength in range of visible light (400-700 nm) by 5 nm. Results from this work had difference from the commercial instrument less than 5%. Accuracy of this setup was proved with standard deviation (SD) and uncertainty about 0.0904 and 0.0286. This work can apply for light source to studies absorption or transmission properties of material in basics laboratory.