NEO Monitors LaserDust Medium Path (MP), Long Path (LP), and Extra Long Path (XLP) Monitors are compact, optical dust monitors for true continuous in-situ mea- surement of dust concentration or opaci- ty. The monitors are designed for measu- rement across pipes, stacks, and ducts with typical path lengths of 0.5 – 10 m. LaserDust Monitors use a transmitter / receiver configuration to probe the dust concentration along the optical line-of- sight. Our true non-contact approach (no probes) is superior to point type dust meters.