Photon Counting systems are unlike linear mode systems in that the sensor transmits low power laser pulses at high frequency to the earth’s surface, which are reflected back to the aircraft where they are captured by a two-dimensional imaging array captures their measurements at the photon level. Each laser pulse results in up to 4,096 responses to the sensor’s array. The group of returns forms an image for each of the 50 khz Laser pulses, resulting in up to 204.8 million elevation measurements per second.

The advantages of this technology are significant. Data can be collected up to 3-4 times faster than linear mode LiDAR from altitudes of 3,500–5,000 meters above ground level. This helps to reduce overall costs. When imaging forested areas, the large number of measurement opportunities distribute themselves throughout the
target, providing many returns throughout the canopy structure and along the ground surface. The resulting point densities are up to 100 points /m2 on ground surfaces and can be well over 200 points/ m2 in forested areas.