A method for enhancement of spontaneous Raman scattering (SRS) from gases comprising a multimode blue laser diode which receives feedback from a near concentric bidirectional multipass cavity in such a way as to generate a circulating power of order 100 W for a sample volume of 10 mm.sup.3. The feedback, provided via a volume Bragg grating, reduces the laser bandwidth to 4 cm.sup.−1. Spectra of spontaneous Raman scattering from ambient atmospheric air, detected collinearly with the pump, were recorded with a limit of detection below 1 part-per-million.

A gas sensor probe having multipoint reflection rectangular absorption cell, a VCSEL laser emitter and a detection device. The probe comprises: an upper cover plate, the surface of the upper cover plate being provided with gas diffusion holes, and a metal filtering screen being provided above the gas diffusion holes; a lower cover plate located under the upper cover plate and detachably connected to the upper cover plate, and an electric wire through hole being formed in the bottom of the lower cover plate; a light path module located in an internal space defined by the upper cover plate and the lower cover plate and used for modulating the laser emitter and collecting a detection signal; and an electronic processing circuit board located in the internal space defined by the upper cover plate and the lower cover plate, located below the light path module, electrically connected to the light path module, and used for processing the signal generated from the light path module.

A method for controlling the flow of gas through a spectrometer, comprising: flowing a gas through a volume of the spectrometer, the volume being a volume through which light from a sample passes along a first path to reach a first detector and the gas being transparent to the light in a spectral region analysed by the spectrometer; transmitting light from a light source along a second path through the gas to a second detector; detecting an intensity of the light from the light source at the second detector at one or more wavelengths of the light; comparing the detected intensity of the light to a respective setpoint corresponding to a desired transmittance of the gas in the volume of the spectrometer and generating at least one error signal based on the comparison; and adjusting a flow rate of the gas through the volume of the spectrometer based on the error signal, in particular to minimise the difference between the detected intensity and setpoint.

This invention relates to retrievable measuring cell for optical measurements in gas, the cell being defined by a gas conducting pipe having an input end adapted to be connected to a gas flow input intruding gas into the cell and an output end adapted to be connected to a gas flow output. The pipe ends also being adapted to be coupled to optical components including an optical transmitter transmitting light into said cell and an optical receiver adapted to receive light having passed through said cell, the optical beam in said cell having a predetermined shape, the optical components including a light source, at least two minors and a light receiver being mounted in known positions on an external frame covered by the pipe ends. The cell has an elongated shape corresponding to the optical beam shape.

A multipass cell assembly for monitoring of fluid is described, as well as fluid processing systems utilizing same, and associated methods of use of such multipass cell assembly for fluid monitoring. The multipass cell assembly is usefully employed in fluid processing operations such as monitoring of vapor deposition process reactants, e.g., reactants used for vapor deposition metallization of tungsten from a tungsten carbonyl precursor.

An optical absorbance spectrometer including a sample housing configured to hold a sample, a light source configured to emit broadband light into the sample housing, one or more reflectors configured to reflect the light such that the light passes through a sample holding volume of the sample housing multiple times, and a sensor arranged to receive the light from the sample housing, after the reflections. The sensor comprises a plurality of detectors configured to detect the intensity of the received light at multiple different wavelengths.

Aspects relate to a compact and low-cost gas analyzer that can be used for different types of gas analysis, such as air quality analysis. The gas analyzer can include a light source, a gas cell configured to receive a sample (e.g., a gas under test), a spectral sensor including a spectrometer and a detector, and an artificial intelligence (AI) engine. Light can enter the gas cell and interact with the sample to produce output light that may be measured by the spectral sensor. The resulting spectrum produced by the spectral sensor may be analyzed by the AI engine to produce a result. The gas analyzer further includes a self-calibration component configured to enable calibration of the sample spectrum to compensate for spectral drift of the spectral sensor.

A breath analyte capture device includes a breath input port into which a user exhales a breath sample, and a cartridge insertion port for receiving a disposable cartridge containing an interactant. During exhalation of a breath sample, at least a portion of the breath sample is routed through the cartridge such that the analyte (such as breath acetone) is captured by the interactant. In some embodiments, the concentration of the analyte in the breath sample is measured by monitoring a chemical reaction that occurs in the disposable cartridge. The chemical reaction may be monitored by illuminating the cartridge at each of multiple light wavelengths while measuring reflected light.

A laser detection system comprises a sample chamber configured to receive and contain a volume of sample gas, one or more lasers within at least one laser housing, wherein each laser is configured to produce a respective laser beam for excitation of one or more different materials in the sample gas and the one or more lasers are outside the sample chamber, a detector apparatus for detecting light output from the sample chamber, a first optical interface to the sample chamber having at least one window that is at least partially transparent to the laser beams from the one or more lasers, wherein the at least one laser housing is positioned in a close-coupling arrangement relative to the at least one window of the first optical interface such that, in use, the laser beams are substantially unmodified by passage between the laser housing and the at least one window.

The optical cell of an elongated shape has an inner space into which gas is introduced and includes: a cell main body forming the inner space; a manifold member being separably connected to an outer surface of the cell main body extending in a longitudinal direction; and a heating mechanism heating the manifold member, in which the cell main body has a through hole penetrating from the outer surface into the inner space, and the manifold member has a gas introduction path extending along the longitudinal direction and guiding the gas, which has been taken in from the outside, from one side to another side in the longitudinal direction and then guiding the gas to the inner space through the through hole.