Theoretical Calculation and Demonstration of High Radiometric Temperature Detection Using A 64 × 128 Pixel SPAD Image Array

The sensitivity of a silicon photomultiplier (SiPM) can be enhanced to the level of single photon detection by combining the outputs of multiple single photon avalanche diode (SPAD) pixels. In this study, we utilized a pixel array consisting of 64x128 SPAD pixels that can switch and combine the outputs of multiple pixels to achieve a high detection dynamic range based on the photon power of the radiometric measurement scenario. Additionally, we accounted for the uncertainty associated with the dark count rate (DCR) in the theory calculation, which enabled us to extend the lowest detectable radiometric temperature to 225°C, matching the theoretical calculation. Moreover, we successfully maintained the capability of detecting the highest temperature at 1050°C, achieving a noise equivalent temperature difference (NETD) value below 1°C. Based on optical system modifications and calculation correction methods, our measurement results support that the SPAD image array is a much better radiometric sensor compared to CMOS sensors and CCD cameras.