Calibration of a newly designed multispectral ultraviolet sensor based on AlGaN photodiodes using solar radiation

Abstract

A newly designed multispectral ultraviolet (UV) sensor based on aluminium gallium nitride (AlGaN) photodiodes was calibrated using the solar UV radiation in three regions namely ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). This UV sensor which was designed with a transimpedance amplifier system, measures the dc voltage output of direct solar UVA, UVB and UVC radiation (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</sub> ,V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> ) in Bangi, Malaysia (2.92°N, 101.78°E, 50 m above sea level). For calibration, this designed UV sensor were used to measure simultaneously with a silicon-based UVA Light Sensor designed with PASCO PASPORT interface, Xplorer GLX Datalogger which measures the UVA radiation intensity, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</sub> . As a result, a linear relationships between the multispectral UV voltages and UVA intensity were obtained and thus, three linear equations of UVA, UVB and UVC radiation intensity as a function of the multispectral UV voltages were derived. Intensity ratios between the three UV region were deduced from the derived intensity equations. The multispectral UV radiation voltages were further analyzed by plotting the UV voltage values with time. Thus, the multispectral UV sensor based on the AlGaN photodiodes was able to be calibrated successfully.