Abstract: Methods and apparatus for detecting and measuring gas flow are disclosed in which lidar distance information, acquired during the detection of gas using a lidar sensor, is used together with prevailing wind data to determine local wind data for the leak location. This local wind data, which may comprise one or more vectors or a 3D wind model, is used in the determination of flow rate.

Abstract: 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.

Abstract: A lidar system for detection of a gas comprises an optical transceiver for transmitting and receiving optical radiation. A method of operating the system comprises performing spatially scanned sensing measurements of the gas across a system field of view, and analyzing the sensing measurements to determine the presence and location of excess of the gas in the system field of view. Based on the determined location, an adjusted system field of view is determined and spatially scanned sensing measurements of the gas are performed across the adjusted system field of view to obtain sensing measurements at higher spatial resolution.

Abstract: A lidar system for detection of a gas comprises an optical transceiver for transmitting and receiving optical radiation. A method of operating the system comprises performing spatially scanned sensing measurements of the gas across a system field of view, and analyzing the sensing measurements to determine the presence and location of excess of the gas in the system field of view. Based on the determined location, an adjusted system field of view is determined and spatially scanned sensing measurements of the gas are performed across the adjusted system field of view to obtain sensing measurements at higher spatial resolution.

Abstract: A lidar system for detection of a gas comprises an optical transceiver for transmitting and receiving optical radiation. A method of operating the system comprises performing spatially scanned sensing measurements of the gas across a system field of view, and analyzing the sensing measurements to determine the presence and location of excess of the gas in the system field of view. Based on the determined location, an adjusted system field of view is determined and spatially scanned sensing measurements of the gas are performed across the adjusted system field of view to obtain sensing measurements at higher spatial resolution.

Abstract: 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.

Abstract: An optical assembly for a laser projection and return laser light detection device comprises a housing; a first series of components arranged in the housing to define an exit path for laser radiation entering from a laser source and then exiting from the housing; a second series of components arranged in the housing to define a return path for scattered returns of the laser radiation entering the housing and passing to a detector; a polarising beam splitter/combiner common to the exit path and the return path arranged to polarise laser light exiting from the housing and to separate scattered laser light returned to the assembly, that is orthogonally polarised to the exiting laser radiation. The polarising beam splitter/combiner forms a window to the housing.

Abstract: 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.

Abstract: A method of operating an optical device, the method comprising tuning a first emission wavelength of a first output radiation of a laser device continuously within a first wavelength spectrum by modulating a drive current thereof with a first drive current modulation having a frequency of at least 100 kHz. The first wavelength spectrum comprises a first spectral feature associated with at least part of a gas absorption spectrum of at least one gas. The method comprises the steps of modulating the first output radiation of the laser device with a first output modulation, the first output modulation comprising a first plurality of binary pulses, scanning the first wavelength spectrum at a rate of at least 1 ?m per second, projecting the first output radiation towards a first target area, receiving scattered radiation from the first target area, and processing the scattered radiation.