An absorption spectrometer which measures a gas component concentration in a measured gas and which operates via wavelength modulation spectroscopy, wherein the light wavelength of a wavelength-tunable light source is periodically varied over a gas component absorption line of interest and simultaneously sinusoidally modulated with a high frequency and a low amplitude signal, and wherein the measurement signal of a detector is demodulated in a phase-sensitive manner at the frequency and/or a harmonic of the frequency and further analyzed, where modulation starts in each period or each n-th period with the frequency in a time interval before the beginning of the time function and is performed with a higher amplitude than during the time function to demodulate the measurement signal in a phase-synchronous manner, where a device provided for the phase-sensitive demodulation is synchronized during the time interval such that a cable for transmitting synchronization signals is no longer necessary.

A method of measuring the concentration of a gas in a target environment using a laser lidar system, comprises directing a laser beam towards an environment containing the gas, tuning the laser wavelength over a wavelength range including the absorption line of the gas, and measuring intensity of laser light returned from the environment containing the gas, as a result of scattering as a function of time. The intensity vs time is then converted into gas absorption vs wavelength, and the gas absorption vs wavelength is used to determine the concentration of the gas in the target environment.

A simple optical layout for a grazing angle probe mount that allows coupling to a mid-infrared (MIR), laser-based spectrometer is provided. The assembly enables doing reflectance measurements at high incident angles. In the case of optically thin films and deposits on MIR reflective substrates, a double pass effect, accompanied by absorption by the chemicals or biological samples deposited in an Infrared Reflection-Absorption Infrared Spectroscopy (IRRAS) modality is achieved. The optical system includes a probe that allows the passage of MIR light through the same sampling area twice. Initially, the infrared beam produces a spot on the surface, and then the light is returned in back reflection to the sample surface producing a new little slightly larger spot onto the selfsame position.

The disclosure relates to system and method for determining at least one property of a porous medium and includes performing a first measurement on a sample of the porous medium obtaining an optical path through pores of the porous medium using a first sensor applied utilizing a first optical technology; performing a second measurement on the sample of the porous medium obtaining a total optical path through the porous medium using a second sensor utilizing a second optical technology different from the first optical technology; and calculating an optical porosity of the porous medium based on the optical path through the pores and the total optical path through the porous medium.

A spectrometry device includes a switch and a converter. The switch acquires a first reception signal and a second reception signal that respectively include information relating to an optical spectrum and switches between outputting the first reception signal and outputting the second reception signal based on control by a controller. The converter converts the first reception signal or the second reception signal output from the switch into a digital signal.

A high-altitude atmospheric sensor may include a frame configured to attach to a body of an aircraft, where the frame defines an open measurement cavity for air to travel through during flight of the aircraft. The sensor may further include one or more light sources providing input light such as mid-infrared quantum cascade lasers, a beamsplitter to separate the input light into measurement light propagating along a measurement path and reference light propagating along a reference path, one or more measurement cells providing optical paths for the measurement light in the open measurement cavity of the frame, one or more detectors to capture the measurement light from the one or more measurement cells and the reference light, and a controller to generate one or more spectroscopy measurements of air passing through the open measurement cavity during the flight of the aircraft.

A method of gas detection comprises emitting radiation of different wavelengths across the absorption spectrum of a gas towards a target area; and analysing the spectrum of returned laser light from the target area to identify the gas in the target area using the time correlation of the emitted radiation and the returning radiation. The radiation is modulated using respective orthogonal modulation codes for the different wavelengths and the modulation codes are modified by the insertion of a gap between each bit of the modulation code, the gap having a duration of at least n-1 bits where n is the number of different wavelengths.

A method of measuring the concentration of a gas in a target environment using a laser lidar system, comprises directing a laser beam towards an environment containing the gas, tuning the laser wavelength over a wavelength range including the absorption line of the gas, and measuring intensity of laser light returned from the environment containing the gas, as a result of scattering as a function of time. The intensity vs time is then converted into gas absorption vs wavelength, and the gas absorption vs wavelength is used to determine the concentration of the gas in the target environment

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.

Systems for measuring a concentration of a target species include a first and second tunable diode laser generating laser light at a respective first and second wavelength each corresponding to respective absorption lines of the target species. A first optical fiber is optically coupled to the first tunable diode laser, and does not support a fundamental mode at the second wavelength. A second optical fiber is coupled to the second tunable diode laser and does not support a fundamental mode at the first wavelength. A fiber bundle includes respective distal ends of the first and second optical fibers, which are stripped of their respective coatings and arranged with their claddings adjacent to each other. A pitch head is configured to project respective optical beams from the fiber bundle through a measurement zone. A catch head located across the measurement zone receives the projected beams and directs them to a sensor.