GAS CONCENTRATION MEASUREMENT DEVICE

摘要

A gas concentration measurement device (100) is provided with: a light source (20) that emits infrared rays; a detector (60) that detects infrared rays via a bandpass filter (41); and a waveguide-forming member (90) comprising a waveguide section (93) that has a cylindrical inner peripheral surface shape, an inlet (91) that is formed on one side of the waveguide section (93) and that introduces infrared rays from the light source (20), and an outlet (92) that is formed on the other side of the waveguide section (93) and that leads infrared rays that have passed through the waveguide section (93) toward the detector (60) side. A tapered area in which the cross-sectional area decreases from the inlet (91) toward the outlet (92) is provided to a part or all of the inner peripheral surface of the waveguide section (93). The waveguide forming-member (90) attenuates the energy of infrared rays that enter obliquely with respect to the bandpass filter (41) by reflecting infrared rays that enter the waveguide section (93) from the inlet (91) toward the tapered area.