Dynamic reconstruction of a calibration state of an absorption spectrometer

An apparatus comprising:

• a non-transitory machine-readable storage medium storing instructions that, when executed by at least one processor, cause the at least one processor to perform operations comprising:
• retrieving a reference harmonic absorption curve of a laser absorption spectrometer, the laser absorption spectrometer comprising a tunable or scannable laser light source and a detector, the reference harmonic absorption curve having a reference curve shape and comprising a first, second, or higher order harmonic signal of a reference signal generated by the detector in response to light passing from the laser light source through a reference gas or gas mixture, the reference gas or gas mixture comprising one or more of a target analyte and a background gas expected to be present during analysis of the target analyte;
• the reference harmonic absorption curve having been determined for the laser absorption spectrometer in a known or calibrated state;
• comparing a test harmonic absorption curve having a test curve shape with the reference harmonic absorption curve to detect a difference between the test curve shape and the reference curve shape that exceeds a predefined allowed deviation and therefore indicates a change in an output of the laser light source relative to the known or calibrated state, wherein portions of the test harmonic absorption curve are compared with portions of the reference harmonic absorption curve arising due to absorption of the background gases and not by absorption of the target analyte;
• and
• adjusting one or more operating and/or analytical parameters of the laser absorption spectrometer to correct the test curve shape to reduce the difference between the test curve shape and the reference curve shape.

A method for implementation by one or more data processors forming part of at least one computing system, the method comprising:

• retrieving, by at least one data processor, a reference harmonic absorption curve of a laser absorption spectrometer, the laser absorption spectrometer comprising a tunable or scannable laser light source and a detector, the reference harmonic absorption curve having a reference curve shape and comprising a first, second, or higher order harmonic signal of a reference signal generated by the detector in response to light passing from the laser light source through a reference gas or gas mixture, the reference gas or gas mixture comprising one or more of a target analyte and a background gas expected to be present during analysis of the target analyte, the reference harmonic absorption curve having been determined for the laser absorption spectrometer in a known or calibrated state;
• continually comparing, by at least one data processor, a test harmonic absorption curve having a test curve shape with the reference harmonic absorption curve to detect a difference between the test curve shape and the reference curve shape that exceeds a predefined allowed deviation and therefore indicates a change in an output of the laser light source relative to the known or calibrated state;
• wherein portions of the test harmonic absorption curve are compared with portions of the reference harmonic absorption curve arising due to absorption of the background gases and not by absorption of the target analyte;
• and
• iteratively adjusting, by at least one data processor, one or more operating and/or analytical parameters of the laser absorption spectrometer to correct the test curve shape until the difference between the test curve shape and the reference curve shape is below a pre-determined threshold.

An apparatus comprising:

• means for retrieving a reference harmonic absorption curve of a laser absorption spectrometer, the laser absorption spectrometer comprising a tunable or scannable laser light source and a detector, the reference harmonic absorption curve having a reference curve shape and comprising a first, second, or higher order harmonic signal of a reference signal generated by the detector in response to light passing from the laser light source through a reference gas or gas mixture, the reference gas or gas mixture comprising one or more of a target analyte and a background gas expected to be present during analysis of the target analyte, the reference harmonic absorption curve having been determined for the laser absorption spectrometer in a known or calibrated state;
• means for comparing a test harmonic absorption curve having a test curve shape with the reference harmonic absorption curve to detect a difference between the test curve shape and the reference curve shape that exceeds a predefined allowed deviation and therefore indicates a change in an output of the laser light source relative to the known or calibrated state, wherein portions of the test harmonic absorption curve are compared with portions of the reference harmonic absorption curve arising due to absorption of the background gases and not by absorption of the target analyte;
• and
• means for adjusting one or more operating and/or analytical parameters of the laser absorption spectrometer to correct the test curve shape to reduce the difference between the test curve shape and the reference curve shape.