Characterization of a modified printed optical particle spectrometer for high-frequency and high-precision laboratory and field measurements

Abstract. The printed optical particle spectrometer (POPS) is a lightweight, low-cost instrument for measurements of aerosol number concentrations and size distributions. This work reports on modifications the Handix Scientific commercial version POPS to facilitate its use in multi-instrument sampling systems. flow system modified by replacing internal pump with needle valve vacuum pump. integrated into closed-flow systems routing sheath from filtered inlet air. A high-precision multichannel analyzer (MCA) card added sample analog pulse signal. MCA polled at 10 Hz frequency using an external data acquisition improves upon count-rate limitation associated system. times required change concentration between 90 % vice versa step were measured be 0.17 0.41 s rate 5 cm3 s−1. yields ∼ 1–2 Hz, below which amplitude fluctuations captured > 70 efficiency. was dual tandem differential mobility explore coalescence dimer particles. Results show that pulse-height response increases coalescence. magnitude increase broadly consistent light-scattering predicted T-matrix method. It anticipated this will extend utilization technique range field laboratory applications.