Differential Absorption LIDAR Imaging

Laser based measurements are increasing being used to extract gas parameters including concentration. If the target gas is present it will absorb laser power, this absorption is proportionally to the concentration of the gas. As well as measuring absorption, range to gas can also be measured by examining the time it takes for the laser pulses to travel, this is known as light detection and ranging (LIDAR). This can be extended by having two laser sources operating at closely spaced wavelengths, one wavelength is highly absorbent to the target gas the other is not. By comparing the detected values for both wavelengths the concentration can be determined, this is known as differential absorption LIDAR (DIAL). This work will develop a bench mounted DIAL system for gas concentration and range measurements.