8x8 single photon counting module for spaceborne lidar

In spaceborne LIDAR, the measurement of both intensity and time of flight of a luminous signal is widely used to investigate the atmosphere and the earth surface. In this scenario, a laser flash is sent from a satellite towards the target and a receiver records the intensity versus time: the recorded time correlates with the distance of the scatterer from the source while the intensity of the signal carries information on scatterer type, number density and intermediate extinction. Starting from an 8x8 array of high-performance Single Photon Avalanche Diodes (SPADs) fabricated with a fully planar custom-technology, we developed a module prototype for spaceborne LIDAR. An alignment board is able to provide the alignment of the trigger signal coming from the laser with the start of the acquisition time with an accuracy better than 1ns. Data coming from the SPAD are then summed and a digital word corresponding to the number of counts in time bins as short as 8.3ns.