An Optical Sensor for Measuring the Particle Size Distribution of Aerosol Without Refractive Index Using the Optimized Multioutput Support Vector Machine

Due to the advantages of noncontact and high sensitivity, the optical light-based method has been widely used to measure the particle size distribution (PSD) of aerosols, where the prior information of refractive index is necessary to retrieve the PSD of aerosols. However, the refractive index of aerosols cannot be obtained in situ and online. To address this challenge, an optical light-based method is proposed to retrieve the PSD of aerosols using the scattering phase function and optimized machine learning without requiring any prior information on refractive index. The scattering phase function is used to describe the scattering light intensity of aerosols that corresponds to different observation angles. Meanwhile, an optical prototype sensor is designed and evaluated through different kinds of aerosol samples. The retrieved PSD was in good agreement with the reference PSD, and the maximum ${D}_{\text {KL}}$ was 0.08. The experiment results proved that the proposed method in this study can retrieve the PSD of aerosols without requiring the information on refractive index, and shows significant potential for measuring the PSD of aerosols in situ and online.