What is LiDAR?
LiDAR stands for Light Detection and Ranging. It’s a laser-based technology used to create highly detailed imagery from a remote distance. LiDAR can use either pulsed laser light or continuous-wave lasers (where laser light stays on all the time) to image something–like ground topography, or even gas concentrations. Bridger Photonics uses LiDAR to measure both solid surfaces as well as gas, known as hard targets and soft targets, respectively.
LiDAR technology is used throughout many industries. Detailed elevation surveys of landscapes using LiDAR are frequently used in floodplain mapping, and autonomous driving technology uses LiDAR scanners attached to cars to provide a high-resolution 3D view of the surroundings. LiDAR is also used in agriculture, land management, meteorology, and more.
Are there different types of LiDAR?
Yes, there are! We can break down the types of LiDAR by application–either topographic or atmospheric.
Topographic LiDAR, or LiDAR that measures distance, can be done with either frequency-modulated continuous-wave (FMCW) methods or direct-detect methods. FMCW LiDAR uses a specific frequency of laser light to measure the distance from the laser to the object of interest. This type of continuous-wave LiDAR measures the time it takes for the laser light to reach and return from the source object using the known speed of light. This is repeated for all parts of the object and a 3D model is created. FMCW LiDAR has finer resolution and is less sensitive to ambient light, but is much more complicated than the direct-detect. Direct-detect, or time of flight, LiDAR, measures the time it takes for the laser light to reach and return from the source object using the known speed of light, similar to FMCW LiDAR. Direct-detect systems are much simpler to build and operate, but require more laser power to work in bright (e.g. sunny) conditions and don’t have some of the other benefits of FMCW LiDAR.
For atmospheric sensing, continuous-wave laser absorption LiDAR or differential absorption LiDAR (DIAL) are common techniques. Continuous-wave laser absorption LiDAR, like that used in Bridger’s Gas Mapping LiDAR™, transmits a continuous laser beam that is tuned to the absorption wavelength of the desired gas (e.g. methane) and measures the amount of light reflected from the ground, back through the gas to the sensor. The continuous nature means much lower peak laser power needed, resulting in smaller, more compact, and safer laser sources. DIAL systems are pulsed lasers much like direct-detect LiDAR. They transmit two laser pulses, the first tuned to the gas absorption wavelength and the second tuned to a non-absorbed wavelength. Comparing the return intensity of both pulses reveals how much gas is in the path. DIAL systems are very sensitive, even able to measure light scattered back from atmospheric particles instead of hard surfaces like the ground. But, they are large, heavy, and complex systems often requiring high peak power laser pulses that are less eye-safe. Because of the size and complexity, DIAL systems are much less suitable for compact aerial deployment.
How Does Bridger Photonics Use LiDAR?
Gas Mapping LiDAR uses a combination of FMCW and continuous-wave laser absorption LiDAR to measure both distance and methane concentrations from the air. We deploy our sensors on small fixed-wing aircraft or helicopters and fly over oil and gas assets across the value chain to detect methane leaks. Our unique LiDAR can be used in most environmental conditions, with a detection sensitivity for methane at 3 kg/hr with a 90% probability of detection in the oil and gas production sector, and as low as 0.25 kg/hr with a 90% probability of detection in the distribution sector.
Want to Learn More About LiDAR?
Check out our LiDAR page to take a deeper dive into the different types of LiDAR, see some example images, and compare the pros and cons of each technique. You can also check out our Gas Mapping LiDAR page to learn more about our innovative methane detection technology.
Contact us to discuss how Gas Mapping LiDAR can be used for your methane detection needs.