Simple Visible Light Spectrophotometer Design Using 620 Nm Optical Filter

The main problem of conventional spectrophotometer is its large form and complex system. This study aims to design and develop a compact and portable visible light spectrophotometer. The main contribution of this study is to simplicity the spectrophotometer design. The designed device uses a halogen lamp as the light source, and a colored lens 620 nm optical glass filters that serve to narrow the wavelength becomes monochromatic. A phototransistor sensor is utilized to convert the monochromatic light into a voltage. A differential filter is employed to reduce 15.9 Hz noise that occurred when the phototransistor detected the light. Furthermore, all processes in the developed system are automatically controlled using ATMega328. The verification of the designed spectrophotometer is carried out using cholesterol serum with various concentrations. The conducted test result shows that the designed system has more than 90% accuracy, with the highest error percentage is 5.52%, and the mean of error percentage is 2.8%. The developed spectrophotometer demonstrated high performance, portable, and cost-effective in analyzing cholesterol serum concentrations. The proposed design of the spectrophotometer was useful in the development of simple and compact devices for chemical sample analysis.