Laser-type gas analyzer

A laser-type gas analyzer, comprising:

• a mid-infrared laser light-emitting unit that emits laser light of a wavelength band of a mid-infrared region that includes an optical absorption spectrum of a first gas to be measured;
• a mid-infrared laser driving unit that drives the mid-infrared laser light-emitting unit;
• a mid-infrared laser optical unit that collimates the laser light emitted by the mid-infrared laser light-emitting unit, and irradiates the light into a space to be measured in which the first gas to be measured is present;
• a mid-infrared light-receiving unit that receives the laser light irradiated by the mid-infrared laser optical unit, and outputs the received laser light as an electrical mid-infrared light reception signal;
• a mid-infrared light reception signal processing and computing unit that extracts, from the mid-infrared light reception signal, a signal component affected by optical absorption by the first gas to be measured, and calculates a gas concentration of the first gas to be measured on the basis of an amount of change of this signal component;
• a near-infrared laser light-emitting unit that emits, at respective times, first laser light of a wavelength band of a near-infrared region that includes an optical absorption spectrum of a second gas to be measured, second laser light of a wavelength band of a near-infrared region that includes an optical absorption spectrum of water, and third laser light of a wavelength band of a near-infrared region in which the optical absorption spectra of water, the first gas to be measured and the second gas to be measured are equal to or smaller than a predetermined amount;
• a near-infrared laser driving unit that drives the near-infrared laser light-emitting unit;
• a near-infrared laser optical unit that collimates, at respective times, the first, second and third laser light emitted by the near-infrared laser light-emitting unit, and irradiates the collimated light to the space to be measured;
• a near-infrared light-receiving unit that receives, at respective times, the first, second and third laser light irradiated by the near-infrared laser optical unit, and outputs the received light as respective electrical near-infrared light reception signals;
• a near-infrared light reception signal processing and computing unit that performs, at respective times, processes of extracting, from the near-infrared light reception signal of the first laser light, a signal component affected by optical absorption by the second gas to be measured, and computing a gas concentration of the second gas to be measured on the basis of an amount of change of this signal component, computing a water concentration in the space on the basis of the near-infrared light reception signal of the second laser light, and computing a light amount decrement due to dust on the basis of the near-infrared light reception signal of the third laser light;
• and
• a gas concentration correcting unit that corrects the gas concentration of the first gas to be measured, as worked out by the mid-infrared light reception signal processing and computing unit and the gas concentration of the second gas to be measured, as worked out by the near-infrared light reception signal processing and computing unit, in use of the water concentration and light amount decrement as worked out by the near-infrared light reception signal processing and computing unit.