Design and implementation of photo-detection circuit for wavelength modulation spectroscopy (WMS) based oxygen sensor

Wavelength modulation spectroscopy is a versatile technique for wide range of applications such as determination of gas/chemical concentration, temperature and velocity/flux of gaseous molecules in industrial, biomedical and aerospace industry. A WMS based system/ sensor consists of various sub-systems. One important subsystem is the photo-detection circuit which is used to detect the laser light and condition it in accordance with the signal processing block. This paper presents the design and simulation results of photo-detection circuit using OrCAD Pspice. This design is implementedand tested for the detection of optical signal and is compared with the already established bench model setup of Tunable Diode Laser Absorption Spectroscopy (TDLAS) based oxygen sensor. The simulation results show that the designed circuit is capable of detecting optical signal in 50uV range.