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 operating an optical device, comprising: tuning a diode laser wavelength spectrum corresponding to at least a first spectral feature associated with an absorption spectrum of a gas; modulating output radiation of the diode laser; transmitting the modulated output radiation of the diode laser through optical guide elements in a scan towards a first target area; receiving scattered diode laser radiation from the first target area and directing it to a detector; correlating the received scattered diode laser radiation with the transmitted first output radiation to create one or more correlated data sets; and forming an area scan of locations in the first target area to determine concentration of the gas between the optical device and the locations, wherein multiple correlated data sets corresponding to fixed spatial points are used for determining concentration of the gas for each of the locations.

Abstract: 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.

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.

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.

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.

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.

Abstract: 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.

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 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.