Devices, systems, and methods for determining gas characteristics to monitor transformer operation include extracting gas from transformer fluid for analysis.

There is provided a resonant cavity system. A first mirror is actuated at a first end of a resonant cavity to move in a direction between a first position relative to a second mirror at a second end of the resonant cavity, at which a cavity length between the first mirror and the second mirror is less than a resonance length for a laser beam, and a second position relative to the second mirror, at which the cavity length is greater than the resonance length. An event is triggered when the cavity length is proximal to the resonance length. The first mirror is continuously actuated to move in the direction between the first position and the second position during the event.

Systems and methods for controlling optical feedback in an optical system. A resonant optical cavity includes at least two cavity mirrors, one of which is a cavity coupling mirror, and has a plurality of optical resonance cavity modes. A radiation source emits a beam of continuous wave radiation and is capable of being scanned whereby a mean optical frequency of the continuous wave radiation beam is adjustable over a range of frequencies, wherein the radiation source is responsive to optical feedback radiation emerging from the cavity, and wherein the mode matching optics couples the beam of continuous wave radiation to the cavity via the cavity coupling mirror. The radiation source and the mode matching optics are aligned so that a mode fill ratio is reduced relative to a maximum mode fill ratio, wherein the laser beam is coupled with a fundamental cavity mode.

Systems and methods for skewed basis set fitting may include obtaining measured absorption data indicative of an amount of absorption of light by a sample gas at each of multiple frequencies, determining an absorption dependent cavity time constant indicative of a skew to the measured absorption data caused by light reflections within a cavity in which the sample gas is contained, obtaining reference absorption data including basis sets indicative of reference amounts of light absorbed by each of multiple gases at each of the multiple frequencies, skewing the reference absorption data based on the absorption dependent cavity time constant to generate skewed reference absorption data, and fitting the measured absorption data to the skewed reference absorption data to identify an amount of at least one constituent gas within the sample gas.

A cavity ring down measurement system comprising a light source in optical communication with a detector through an optical cavity wherein the detector is in electronic communication through a gating circuit with a first integrating circuit and a second integrating circuit, controlled to obtain a ring up signal simultaneous with a ring down signal of a plurality of ON-OFF cycles over a single period of time. A process to utilize the system is also disclosed.

The invention relates to a method for measurement and monitoring of analytes, for example ketones, particularly but not exclusively acetone in human or other mammalian breath. The invention also relates to apparatus for use in performance of the method. The present invention uses a spectroscopic technique known as CELIF which is a direct combination of the well-established and powerful laser-spectroscopic techniques cavity ring-down spectroscopy and laser-induced fluorescence. The method utilises a flow body to control a flow of sample gas through a laser beam.

Apparatuses, methods, and systems for generating signatures based on sensing one or more gas concentration conditions are disclosed. One method includes sensing, by one or more sensors, levels of a gas over time for a plurality of gas concentration conditions, receiving, by a controller, the sensed levels of gas over time for the plurality of gas concentration conditions, and generating, by the controller, a plurality of signatures, wherein one or more signatures is generated for one or more gas concentration conditions based on the sensed levels of gas over time, and determining whether to take action or not to take action.

Interleaved data acquisition in optical spectroscopy is used to provide interference correction for time-varying interference. Measurements at a reference frequency are used to provide an estimate of the interference. These reference measurements are interleaved with the remaining measurements in order to provide estimates of the interference vs. time at relevant times. The interference being corrected can be spectrally structured or unstructured.

A cavity ring down measurement system comprising a light source in optical communication with a detector through an optical cavity wherein the detector is in electronic communication through a gating circuit with a first integrating circuit and a second integrating circuit, controlled to obtain a ring up signal simultaneous with a ring down signal of a plurality of ON-OFF cycles over a single period of time. A process to utilize the system is also disclosed.

Methods and systems for analyzing a sample and generating a predictive model using cavity ring-down spectroscopy are disclosed. At least part of a sample is loaded in a ring-down cavity. For each of a set of wavelengths, a laser beam is generated and directed into the ring-down cavity. The laser beam entering the ring-down cavity is extinguished. Light intensity decay data for light exiting the ring-down cavity is registered via a light intensity sensor system. A probability is determined from the light intensity decay data for the set of wavelengths that a subject from which the sample was received has a physiological condition or a degree of the physiological condition at least indirectly using a dataset of light intensity decay data for previously analyzed samples for which the presence or the absence of the physiological condition or the degree of the physiological condition have been identified.