Practical Open-Path Instrumentation Performance

摘要

Open path is a measurement technique that quantifies the presence of gas over long distances. The long path lengths used provide significant sensitivity and coverage advantages over point source ambient pollution monitoring. A second consequence of this long path length is confusing, variable, and poorly understood specifications. This work reviews the three major open path technologies, and the measurement errors associated in each specific- case. Practical measurement limits are found. These are based on factors encountered in the field such as alignment and humidity as opposed to random error measured under controlled conditions. Optimal performance of these instruments is predicted with respect to the two adjustable variables, path length and integration time.