GAS ABSORPTION SPECTROSCOPIC SYSTEM AND GAS ABSORPTION SPECTROSCOPIC METHOD

摘要

Provided is a gas absorption spectroscopic system and gas absorption spectroscopic method capable of accurately measuring the concentration or other properties of gas even in high-speed measurements. Laser light with a varying wavelength is cast into target gas. A spectrum profile representing a change in the intensity of the laser light transmitted through the target gas with respect to wavelength is determined. For this spectrum profile, polynomial approximation is performed at each wavelength point within a predetermined wavelength width, using an approximate polynomial. Based on the coefficients of the terms in the approximate polynomial at each point, an nth order derivative curve, where n is an integer of zero or larger, of the spectrum profile is created. A physical quantity of the target gas is determined based on the thus created nth order derivative curve.

主权项

1. A gas absorption spectroscopic system, comprising:
a) a wavelength-variable light source; b) a light source controller for varying a wavelength of light generated by the light source; c) a photodetector for detecting an intensity of light generated by the light source and transmitted through target gas; d) a polynomial approximator for creating a curve approximating a change in the intensity of the light detected by the photodetector with a change in the wavelength varied by the light source controller, using an approximate polynomial at each wavelength point and within a predetermined wavelength width; e) a derivative curve creator for creating an nth order derivative curve, where n is an integer of zero or larger, based on a coefficient of each term of the approximate polynomial at each of the wavelength points; and f) a physical quantity determiner for determining at least one among the temperature, concentration and pressure of the target gas, based on the nth order derivative curve.