Real-Time Ultraviolet Flame Detection System Based on 4H-SiC Phototransistor

High-sensitivity ultraviolet (UV) photoelectric detection technology is significant in UV communication, missile tail flame radiation detection, and fire early warning. This article utilized a 4H-SiC phototransistor detector to respond to weak UV light. A corresponding detection circuit system was developed to convert the photogenerated analog current signal to a digital voltage signal and transmit the digital signal to the host computer. A trans-impedance amplifier amplifies and transfers the weak photocurrent into a large voltage signal, which possesses a stronger antijamming ability. The analog-to-digital converter converts the analog voltage signal into a digital signal for convenient transmission in the following circuits. A universal serial bus interface module transmits the digital signal to the host computer using a serial transmission method with a field-programmable gate array controlling the timing. A graphical software interface based on LabVIEW was developed to display the collected digital data that stand for real-time UV intensity. Monitoring and recording the weak optical power of the UV light emitted by candlelight can be realized via the system. The UV power density range was between 50 nW/cm $^{\text{2}}$ and 3 $\mu$ W/cm $^{\text{2}}$ , and the corresponding output voltages ranged from 0.095 to 3.45 V. Compared with traditional high-voltage biased p-i-n avalanche diode detection system, the flame detection system demonstrated in this article was based on a 4H-SiC phototransistor, which has the advantages of low voltage and high stability.