LIDAR: Single-photon lidar yields rapid topographic and bathymetric coverage

摘要

In September 2011, Laser Focus World described the capabilities of a single-photon-sensitive light detection and ranging (lidar) system developed by Sigma Space Corporation (Lanham, MD). Passing a low-power, high-repetition-rate 532 nm green laser beam (140 mW at 20 kHz) through a diffractive optical element (DOE) generated a 10 × 10 array of low-power (1 mW) beamlets and allowed surface measurement rates up to 2 megapixels per second (Mp/s). This early system generated (in a single overflight) contiguous high-resolution 3D topographic images of low-reflectance tree canopies and high-reflectance cryospheric surfaces from altitudes above ground level (AGLs) of 1 and 2.5 km (3.3 and 8.2 kft), respectively, while traveling at a maximum speed of 88 knots (161 km/hr). With a maximum swath of 0.5 km at 1 km altitude, this limited areal coverage to around 80 km~2/hr. Today, Sigma's improved single-photon-sensitive lidars operate at AGLs up to 8.5 km (28 kft) with swaths up to 2.5 km.