Optical Sensor for UV Radiation

Team members

LiJiasheng, ChenXingjian, LiXuejian

Introduction

Ultraviolet (UV) radiation, a fundamental component of sunlight, is critically influential in numerous environmental and biological processes. These processes range from the synthesis of Vitamin D in humans to the degradation of materials exposed to outdoor environments. Monitoring UV radiation is not only essential for assessing its ecological impacts but also for various practical applications including weather forecasting, climate monitoring, and public health advisories against UV overexposure.

Given the significance of accurately measuring UV radiation, the development of reliable and precise UV sensors is of paramount importance. The optical sensor designed in this project utilizes the S5971 photodiode from Hamamatsu, known for its high sensitivity and low noise characteristics, making it an excellent choice for precision light measurements.

The primary objective of this experiment is to develop an optical sensor that can accurately measure the UV component of sunlight. The S5971 photodiode, although highly sensitive, produces only minimal photocurrent under indoor lighting conditions, necessitating the use of a Transimpedance Amplifier (TIA) circuit to convert this small current into a measurable voltage.The designed sensor system integrates the S5971 photodiode with a TIA circuit to amplify the weak signals produced when exposed to light sources. By measuring the voltage across the resistor in the TIA circuit, the amplified voltage corresponding to the intensity of incident light can be determined. This setup allows for the derivation of a quantitative relationship between light intensity and output voltage.

To specifically measure UV light intensity, the sensor system is tested under various conditions: with direct white light (representing broad-spectrum sunlight) and white light passed through a UV-pass filter. By comparing these measurements, the proportion of UV light in natural sunlight can be inferred, providing valuable data for environmental and health-related applications. This project not only aims to develop a functional UV light sensor but also to enhance understanding of UV radiation's variability with daily and seasonal changes in sunlight exposure. This knowledge is crucial for applications ranging from solar power generation to environmental science studies and public health initiatives.

Setup

UV Photodiode(280-320nm)

Optical Filters

Analog-to-Digital Converter

Temperature Sensor

Measurements

Selecting the Right Photodiode: According to our research, among different types of UV radiation(UVA, UVB, and UVC), UVB is the primary concern for skin damage and vitamin D synthesis, which wavelength is about 280-320 nm; UV-Specific Photodiodes are usually made of silicon carbide (SiC) or gallium nitride (GaN), which have high sensitivity for UV light.

Designing the Detection Circuit: First, we need to design a circuit that can amplify the weak current generated by the photodiode upon UV exposure. We also need optical filters, which help improve accuracy by ensuring only the desired UV light is detected. Finally, we need a Analog-to-Digital Conversion (ADC), since we need to convert the analog signals from your sensor into digital data: most computers only work with digital signals.

Data Processing and Presentation: We need to choose a microcontroller that can process the signals from your ADC, performing necessary calculations to determine the UV index. We also need an LCD display, smartphone app, or website for displaying the UV index in real-time.

Expected Results:

We expect that finally we can get a photodiode-based sensor to detect UV radiation levels, which can be used for monitoring the real-time UV index of the environment.