Development of fast-response portable NDIR analyzer using semiconductor devices

Abstract

In this paper, a novel fast response NDIR analyzer (FRNDIR), which uses an electrically pulsed semiconductor emitter and dual type PbSe detector for the PPM-Ievel detection of carbon dioxide (CO₂) at a wavelength of 4.28㎛, is described. Modulation of conventional NDIR energy typically occurs at I to 20 Hz. To achieve real time high-speed measurement, the new analyzer employs a semiconductor light emitter that can be modulated by electrical chopping. Updated measurements are obtained everyone millisecond. The detector has two independent lead selenide (PbSe) with lR band pass filters. Both the emitter accuracy and the detector sensitivity are increased by thermoelectric cooling of up to - 20 degrees C in all semiconductor devices. Here we report the use of semiconductor devices to achieve improved performance such that these devices have potential application to CO₂ gas measurement and, in particular. the measurement of fast response CO₂ concentration at millisecond level.