Gas analyzer

A gas analyzer comprising:

• an optical emitter that irradiates measurement light into a measurement region including a measured-gas;
• a first optical receiver that receives the measurement light after the measurement light passes through the measurement region;
• a beam splitter disposed between the optical emitter and the measurement region and that splits off a portion of the measurement light irradiated from the optical emitter to yield reference light;
• a reference unit that holds a gas, containing an identical measurement target component with the measured-gas, at a known concentration, and that comprises a second optical receiver that receives the reference light after the reference light passes through a region of the reference unit;
• and
• an optical component disposed between the beam splitter and the region,
• wherein the optical component expands a beam diameter of the reference light to be larger at the second optical receiver than a receiving diameter of the second optical receiver.