Abstract: Embodiments of the disclosure are drawn to apparatus and methods for determining gas flux measurements. A gas plume may be emitted from a source and may be blown by wind in an environment. A measurement system, such as a light detection and ranging (lidar) system may collect a plurality of gas concentration measurements associated with the gas plume at a plurality of locations in the environment. A gas flux may be determined based on one or more of the gas concentration measurements along with a wind speed at a location associated with the gas plume. In some embodiments, a height of the gas plume may be determined, and the wind speed at the height of the gas plume may be determined and used to determine the gas flux.

Abstract: Embodiments of the disclosure are drawn to apparatuses and methods for anomalous gas concentration detection. A spectroscopic system, such as a wavelength modulated spectroscopy (WMS) system may measure gas concentrations in a target area. However, noise, such as speckle noise, may interfere with measuring relatively low concentrations of gas, and may lead to false positives. A noise model, which includes a contribution from a speckle noise model, may be used to process data from the spectroscopic system. An adaptive threshold may be applied based on an expected amount of noise. A speckle filter may remove measurements which are outliers based on a measurement of their noise. Plume detection may be used to determine a presence of gas plumes. Each of these processing steps may be associated with a confidence, which may be used to determine an overall confidence in the processed measurements/gas plumes.

Abstract: Examples are provided that use multiple analog-to-digital converters (ADCs) to disambiguate FMCW ladar range returns from one or more targets that may be greater than the Nyquist frequencies of one or more of the ADCs. Examples are also provided that use a first and a second laser FMCW return signal (e.g., reflected beam) in combination with two or more ADCs to disambiguate one or more target ranges (e.g., distances to one or more objects).

Abstract: Examples of FMCW laser radar systems and methods described herein may segment the processing of a broader bandwidth frequency chirp into multiple shorter-duration (e.g., lower bandwidth) frequency chirps. This segmentation may have the benefits in some examples of improving the measurement duty cycle and range resolution, and/or allowing for more flexible processing, and/or enabling improved detection of more distant objects.

Abstract: Methods and apparatuses are described for frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR). Examples are provided where high-closed-loop bandwidth, active feedback applied to laser frequency chirps may provide increases in the free-running laser coherence length for long-range FMCW distance measurements. Examples are provided that use an asymmetric sideband generator within an active feedback loop for higher closed-loop bandwidth. Examples of using a single shared reference interferometer within multiple active feedback loops that may be used for increasing the coherence length of multiple chirped lasers are described. Example calibrators are also described.

Abstract: Measurement apparatuses and methods are disclosed for generating high-precision and -accuracy gas concentration maps that can be overlaid with 3D topographic images by rapidly scanning one or several modulated laser beams with a spatially-encoded transmitter over a scene to build-up imagery. Independent measurements of the topographic target distance and path-integrated gas concentration are combined to yield a map of the path-averaged concentration between the sensor and each point in the image. This type of image is particularly useful for finding localized regions of elevated (or anomalous) gas concentration making it ideal for large-area leak detection and quantification applications including: oil and gas pipeline monitoring, chemical processing facility monitoring, and environmental monitoring.