The High Spectral Resolution LiDAR (HSRL) instrument is an airborne LiDAR system, designed to provide measurements of aerosol backscatter and extinction coefficients and aerosol depolarization at two wavelengths. A unique design element of the system is the ability to calibrate the instrument internally, eliminating reliance of calibration from atmospheric targets.
The HSRL instrument consists of a laser transmitter, a 16-inch (40.6-cm) telescope and a receiver. As in other LiDAR systems, the transmitter sends light rays into the atmosphere and the reflected light is collected by the telescope and fed to the receiver.
The instrument was collecting LiDAR data within one week of delivery of the optomechanics to NASA for integration of the electronics and laser. It bolted directly into the airplane for its first deployment without ever being at the aircraft beforehand for fitting and match drilling, a testament to our ability to make things fit right the first time.
HSRL continues to fly and collect data today. WMD has provided several upgrades to the system over the years, including an upgraded laser transmit system in 2013 and a spectral purity monitor and new structural tilting mount in early 2014. The tilting mount allows the instrument to be tilted 15 degrees both fore and aft in the aircraft for making a special measurement type over water. In the spring of 2014, WMD also provided several newly designed hybrid detector modules to further increase the capabilities of this instrument.
HSRL was one of WMD's first system deployments that included transmit, telescope and receiver optical systems in one relatively compact unit, and has proven to be a great success. The robustness of the original design was such that we have been able to easily incorporate all the upgrades listed above, and are currently engineering other upgrades to further enhance this instrument.
It is a testament to our design quality and flexibility that the HSRL instrument is still flying today as a workhorse for the atmospheric science community.