Device for Measurements of Ultraviolet’s Power Radiation

Abstract

The paper presents a technique for developing a device for measurements of power of ultraviolet (UV) radiation. The paper provides a brief analysis of existing approaches in the design of UV dosimeters. The rationale for the design of the dosimeter using an UV photodiode is given. The choice of a photodiode based on cadmium sulfide is made on the basis of the technological equipment existing in Ukraine, the level of development of technological modes that allow, at low technology costs, to obtain photodiodes with parameters not inferior to expensive foreign analogues based on materials of the A3B5 group and silicon carbide. The problems that were solved when developing a photodiode based on CdS and the original solutions found by the authors of the development are shown. The primary transducer is a photodiode based on the surface-barrier structure of p-Cu1.8S/n-CdS with a photosensitive component based on cadmium sulfide CdS. At a wavelength of λ ~ 250 nm, the sensitivity of p-Cu1.8S/n-CdS sensors is two times higher than GaP-based Schottky diodes. The value of the output current depends on the power of the UV radiation and lies within 0.0001-0.2 mA. The advantages of the developed sensor are the simplicity and low cost of the production technology, the ability to produce films of a large area, the characteristics of expensive foreign industrial UV photodiodes. The stages of development of the amplifier circuit for the selected photodiode are given. To design the amplifier circuit, the existing GUVA-S12SD UV Sensor V2 amplifier circuit was analyzed, and a custom circuit was developed with the following advantages: unipolar power; smaller potential difference between input and output compared to analog; different voltages are measured. The developed circuit uses the simplest resistive voltage divider, which is two series resistors connected to a voltage source. The scheme denominations were calculated. The sequence of printed circuit board (PCB) execution in the Sprint-Layout software environment is described. An image of the developed circuit board is shown. An analog-to-digital converter K1108PV1A is selected for signal processing from the amplifier and its technical characteristics are given. The block diagram of the dosimeter of energy illumination is offered: a photodiode, an amplifier of an input signal, an analog-to-digital converter, a microcontroller. As a microprocessor to be connected to the ADC, an electronic stand based on a microcontroller will be used to debug programs using ATmega16A. The obtained circuit solutions for the construction of a UV dosimeter based on a CdS photodiode can be used to quickly create an industrial device that will be an integral part of the complexes for disinfecting the metro and other rooms from viral infections.