Senscient Tutorial Paper ISA Analytical Division Symposium…

ELDS - Enhanced Laser Diode Spectroscopy Lee Richman Director Senscient Ltd Wareham, BH20 7BX UK KEYWORDS Laser Diode Spectroscopy, Gas Detection, ELDS. ABSTRACT Laser Diode Spectroscopy (LDS) is a well known method for the sensitive detection and measurement of gases, with techniques including WMS (Wavelength Modulation Spectroscopy), FMS (Frequency Modulation Spectroscopy) and TTFMS (Two Tone Frequency Modulation Spectroscopy) being successfully employed in a variety of applications. However, due to a number of significant shortcomings, LDS has not seen widespread application in the detection of hazardous gases for safety related applications. Enhanced Laser Diode Spectroscopy (ELDS) has been developed to overcome the shortcomings of previous LDS techniques, enabling it to be used in the most demanding safety related gas detection applications. INTRODUCTION Laser diode spectroscopy techniques have been widely used in instrumentation to measure gases in industrial processes and to monitor atmospheric pollutants. However, equipment using LDS techniques has only enjoyed limited success in the detection of toxic or flammable gases for safety related applications. The main reason that LDS based equipment has not been widely employed for the detection of toxic or flammable gases for safety related applications is that such applications demand an extremely high level of reliability and in particular very low false alarm rates. The ...