A Fast Response UV-Absorption Ozone Photometer using a Differentially-Phased Triple-Cell System

A new fast-response ozone photometer which uses ultraviolet (UV)-absorption is described. Its three UV-absorption cells each cycle among three modes: reference, sample and transition modes. The three cells are differentially phased, enabling the ozone concentration to be determined in a cell in one second without interruption. The system is efrective for measurements requiring a fast response, such as measurements on aircraft. We made a trial instrument that adopts this system and confirmed its theoretically predicted operation. The trial instrument showed a significantly faster response than earlier types of ozone photometers. This system may be applicable to other gas measurements that uses UV-absorption.