Dual-wavelength optical sensor for fire detection and measurement of aerosol mass concentration

Currently, optical sensors are focused on improving the sensitivity to enable the detection of ultra -early fire. However, these optical sensors are extremely susceptible to false alarms due to the interference of non -fire aerosols. Concurrently, the response of black smoke is lower than white smoke, which could result in omission alarms. To address these challenges, a new method employing polarization information is proposed to eliminate the interference of non -fire aerosols, and accurately measure the mass concentration of fire smoke. Meanwhile, a correction factor is used to improve the response sensitivity of black smoke. A dual -wavelength optical sensor is designed and tested by di-ethylhexyl-sebacat (DEHS) monodisperse aerosols, fire smoke and non -fire aerosols. The experiment results prove that the proposed method can realize the fire detection with the measurement relative error ( RE ) of polarization degree (PD) ranged from 0.74% to 11.11% with an average of 6.43%. Meanwhile, the measurement RE of the mass concentration of black and white smoke is 17.17% and 1.32%, respectively. The proposed method and optical sensor can effectively eliminate the interference of nonfire aerosols and improve the response sensitivity of black smoke, which can substantially curtail the incidence of nuisance and omission alarm with simple structure and low cost.