In order to make it possible to conduct a zero calibration even though an interference gas exists in a measurement area of a detector, a light absorbance analysis apparatus includes a detector that detects an intensity of light that transmits a gas, a total pressure sensor that measures a total pressure of the gas, an absorbance calculating part that calculates an absorbance based on an output value of the detector and a previously set zero reference value, a partial pressure—absorbance relation storing part that stores a partial pressure—absorbance relational data that indicates a relationship between a partial pressure of an interference gas that exists in a measurement area of the detector and an absorbance calculated by the absorbance calculating part, and a partial pressure calculating part that calculates an interference gas partial pressure as a partial pressure of the interference gas.

A method for identifying the impact on data, such as experimental data, of interfering effects, such as unwanted auto-fluorescence, fluorescence quenching, and fluorescent-sample deterioration, whether or not the data fulfill certain criteria with respect to a threshold indicative of the interfering effects.

In order to make it possible to conduct a zero calibration even though an interference gas exists in a measurement area of a detector, a light absorbance analysis apparatus includes a detector that detects an intensity of light that transmits a gas, a total pressure sensor that measures a total pressure of the gas, an absorbance calculating part that calculates an absorbance based on an output value of the detector and a previously set zero reference value, a partial pressureabsorbance relation storing part that stores a partial pressureabsorbance relational data that indicates a relationship between a partial pressure of an interference gas that exists in a measurement area of the detector and an absorbance calculated by the absorbance calculating part, and a partial pressure calculating part that calculates an interference gas partial pressure as a partial pressure of the interference gas.

A method of identifying the presence of a first gas such as methane within a sample, for example containing natural gas. A detector is provided having a sensor responsive to a first wavelength, a sensor responsive to a second wavelength, and a sensor for collecting reference readings. A gas sample is analysed to obtain a first absorption reading corresponding to the first wavelength, a second absorption reading corresponding to the second wavelength and a reference reading. A first absorption figure is calculated using the first absorption reading and the reference reading, and a second absorption figure using the second absorption reading and the reference reading. The sensor for each wavelength is calibrated for detecting the first gas such that the data collected at each wavelength gives the same reading when only said first gas is present in a sample.

A method of identifying the presence of a first gas such as methane within a sample, for example containing natural gas. A detector is provided having a sensor responsive to a first wavelength, a sensor responsive to a second wavelength, and a sensor for collecting reference readings. A gas sample is analysed to obtain a first absorption reading corresponding to the first wavelength, a second absorption reading corresponding to the second wavelength and a reference reading. A first absorption figure is calculated using the first absorption reading and the reference reading, and a second absorption figure using the second absorption reading and the reference reading. The sensor for each wavelength is calibrated for detecting the first gas such that the data collected at each wavelength gives the same reading when only said first gas is present in a sample.

A detector has a sensor responsive to a first wavelength, a sensor responsive to a second wavelength, and a sensor for collecting reference readings. A gas sample is analyzed to obtain readings corresponding to the first wavelength, the second wavelength and a reference. A first absorption figure is calculated using the first reading and the reference reading, and a second absorption figure using the second reading and the reference reading. A linearizer function is applied to the first and second absorption figures to calculate first and second concentration figures. The sensor for each wavelength is calibrated for detecting the first gas such that the data collected at each wavelength gives the same reading when only the first gas is present. The ratio of the first concentration figure to the second concentration figure is used to identify whether only the first gas is present.

A detector has a sensor responsive to a first wavelength, a sensor responsive to a second wavelength, and a sensor for collecting reference readings. A gas sample is analysed to obtain readings corresponding to the first wavelength, the second wavelength and a reference. A first absorption figure is calculated using the first reading and the reference reading, and a second absorption figure using the second reading and the reference reading. A lineariser function is applied to the first and second absorption figures to calculate first and second concentration figures. The sensor for each wavelength is calibrated for detecting the first gas such that the data collected at each wavelength gives the same reading when only the first gas is present. The ratio of the first concentration figure to the second concentration figure is used to identify whether only the first gas is present.

A method and system for correcting the effect of intensity fluctuations of the transmitted light in an absorption spectroscopy system used for the detection or measurement of chemical species in a medium, whereby one or more modulation bursts are imposed onto a light beam that passes through the medium. This burst signal may be obtained by modulating the bias current of a tunable diode laser, and the modulation burst signal may be optimally at the second harmonic of the modulation frequency of a wavelength modulated beam to allow usage of the same signal path processing used for the spectroscopic detection of the measurand for a second harmonic detection system. The burst signal can be controlled using a smooth window function to minimise the effects of non-linear perturbations that are inherent in tunable diode laser wavelength modulation spectroscopy systems, of optical interference fringes (etalons) and of the residual light absorption by background chemical species or the measurand at the wavelength coinciding with the modulation burst.

A system and method for noise suppression using signal strength ratio metric modulated light are disclosed. The system may include a light source, a light sensor, and a control circuit. The control circuit may be to generate a signal strength ratio metric modulated signal at a modulation depth. The control circuit may also be to send the signal strength ratio metric modulated signal to the light source to cause the light source to emit a signal strength ratio metric modulated light beam. The control circuit may additionally be to receive a reflected light signal from the light sensor. The reflected light signal may include a signal indicative of a reflection of the signal strength ratio metric modulated light beam and a signal indicative of a noise light.