SI-111 (prototype IRR-P) is a high-precision infrared temperature sensor manufactured by CSI using Apogee's infrared probe. It adopts an optical germanium lens and is based on the principle of infrared temperature measurement, which can perform uninterrupted measurements under field conditions. SI-111 consists of a thermopile (used to measure surface temperature) and a thermistor (used to measure the sensor's own temperature), both temperature probes are placed inside an aluminum conduit. Both thermopiles and thermistors output millivolt voltage signals. The sensor collects observation data through the CR series data collector produced by CSI, and performs temperature correction through formulas to obtain more accurate temperature data.