Characterizing optical filters for wildfire detectors

Abstract

Near infrared detectors have gained popularity, mainly in the military, because of their capability of detecting wildfires. The Council for Scientific and Industrial Research (CSIR) focuses on the development and deployment of wildfire detectors within the Southern hemisphere, specifically in Pretoria. These detectors employ ultra narrow bandpass filters which highly transmit desired wavelengths including near-infrared regimes, where wildfire detection is possible. However, these filters are dependant on environmental conditions such as temperature change. Temperature variations cause sensitivity on the angle of incidence and wavelength shift, which reduces filter transmission. Here, we characterize optical filters which can be integrated to the CSIR’s wildfire detectors. We select the best performing optical filters which optimally transmit and 770 nm and block unwanted wavelengths at different angles of incidence and temperatures.