Various technologies for measurement of properties of a particulate suspended in a gas phase via laser-induced incandescence (LII) are described herein. A beam of light can be emitted into a multi-pass optical cell using a laser. The multi-pass optical cell comprises a system of one or more mirrors that repeatedly reflects the beam through a measurement region, stimulating incandescence of particulates present in the measurement region. An LII detection system having a field of view that encompasses the measurement region then receives blackbody or quasi-blackbody radiation emitted by the incandescing particles and outputs data indicative of one or more properties of the particulates in the measurement region.