A tunable optical filter (TOF) based acetylene sensing system is proposed in this paper. By
modulating the wavelength of TOF within the width of one absorption line of acetylene, both the
sensitivity and selective sensing properties of the system for sensing acetylene have been much
improved. Approximate linear calibration curves in sensing acetylene is obtained by experiments. The
minimum detectable acetylene concentration of 5ppm is also achieved by experiments. The proposed
system has great potential in developing mixed-gas sensing system.