Imaging-based lidar for atmospheric remote sensing: A review

Lidar, an active optical remote sensing technique with high spatiotemporal resolution and large detection range, is capable of profiling a variety of atmospheric parameters such as aerosols, trace gases, temperature, pressure, etc., from the ground to the upper atmosphere, providing a crucial tool for air pollution monitoring, regional and global climate change studies and environmental management. In spite that the pulsed lidar technique based on the time-of-flight (TOF) principle has been widely used in atmospheric remote sensing nowadays, the first atmospheric lidar system, dating back to pre-laser times, was based on photography. In recent years, promoted by rapid developments in semiconductor and laser technologies, the imaging-based lidar technique, often utilizing laser diodes as light sources and image sensors as detectors, has also been rapidly developed and found numerous applications in atmospheric remote sensing, e.g., atmospheric aerosol extinction coefficient or optical depth measurements, pollution source tracking, aerosol polarization or size studies, aerosol scattering phase function studies, calibration of the geometrical form factor for pulsed lidar systems, atmospheric gas sensing. This paper elaborates on the fundamental principles, nomenclature, and theoretical descriptions of imaging-based lidar, discusses the system design and summarizes typical system architectures. Furthermore, this article also reviews recent advancements of the imaging-based lidar in atmospheric remote sensing and outlines its future prospect.