Compact Cavity-Enhanced Aerosol Detector using Incoherent Light Sources

TL;DR

This paper presents a compact, portable aerosol detector that enhances light scattering within a high finesse Fabry-Perot cavity using incoherent light sources, enabling detection of ultrafine particles below 300 nm.

Contribution

The authors demonstrate a miniaturized cavity-enhanced aerosol detector using incoherent light sources, reducing size and vibration sensitivity compared to laser-based methods.

Findings

Detects ultrafine particles below 300 nm

Reduces instrument size to below 1 cm cavity separation

Insensitive to vibration due to incoherent light sources

Abstract

We have realized a compact optical particle counter utilizing enhancement of light scattering within a high finesse Fabry-Perot optical cavity. In contrast to laser-based approaches such as cavity ringdown spectroscopy we use the light stream from both superluminescent and light-emitting diodes that have no longitudinal coherence. This eliminates the vibration sensitivity that is typical of laser-based cavity methods. The use of the transmission mode of detection allows us to reduce the cavity mirror separation to below 1 cm, with no obvious limit to miniaturization. Typical light scattering instruments are larger, in part due to their sensitivity to background signals from the light source. Our approach paves the way toward a new generation of compact and portable instruments. A simultaneous comparison of the scattering signals with a commercial particle counter shows that our cavity is also sensitive to ultrafine particles below 300 nm diameter that are typically not recorded in such counters.