Methane Gas detection sensors: THERMAL vs LASER ?
Which is better for UAV based methane gas detection: Thermal or Laser sensors?
How does methane gas detection with a laser detector work?
Laser technology enables gas leaks to be located by pointing the laser beam towards the suspected leak, or along the survey line. The laser beam directed at targets such as gas piping, the ground, etc. A diffused beam is reflected back from the target. The device receives the reflected beam and measures the absorptivity of the beam, which is then calculated into methane column density (ppm-m).
How does methane gas detection with a thermal camera work?
If a thermal camera reads a scene with a gas leak, objects in the angle of view will radiate and reflect infra-red radiation that will react through the lens and the filter on the detector.
The filter only lets some wave lengths of radiation enter the detector from which the camera generates an image of the radiation.
If there is a cloud of gas between the lens and thermal camera, this gas will selectively absorb radiation to the extent of its spectral absorption. The amount of radiation passing through the gas which affects the detector will be lower.
A brief comparison
The laser detector allows gas hot-spots to be detected only at locations in a narrow field of view of the “one point”. The thermal camera, on the other hand, makes it possible to detect and measure hot-spots in the entire image which it is able to observe with its lens.
For example, a 320×240 resolution thermal camera allows visualisation and therefore detection of gas leaks on large areas due to the relatively large field of view and the large number of detectors.
During a one flight, you are able to control about 150m x 150m (at an altitude 80 m) area or about a pipe line up to 1000 m in length.
The following table provides more details of the differences between the two types of sensors against a broad array of dimensions:
Infrared vs Laser sensor comparison
Long term Stability
Single Channel stability
Type of measurement:
- Infrared sensors detect a wider range of gases over a wider area. The operator still has to CONSTANTLY MONITOR the image stream.
- Laser sensors, which are much sharper with a quicker response, automatically detect the relevant gas. Then, in conjunction with infrared and optical cameras, take both a visual and a thermal snapshot of the identified leak.
The Remote Laser Gas Detector UAV can efficiently and rapidly detect methane gas from 30 meters away. This allows for accurate remote sensing on a UAV platform. With the fast detection rate, a UAV can rapidly cover a large area allowing for quick and efficient pipeline inspections.