Sub-pixel micro-scanning for improved spatial resolution using single-photon LiDAR

We present a method of improving the spatial resolution of a single-photon counting light detection and ranging system using a sub-pixel micro-scanning approach. The time-correlated single-photon counting technique was used to measure photon time-of-flight from remote objects. The high-sensitivity and picosecond timing resolution of this approach allows for high-resolution depth and intensity information to be obtained from targets with very low average optical power levels. The system comprised a picosecond pulsed laser source operated at a wavelength of 1550 nm and a 32 x 32 InGaAs/InP single-photon avalanche diode detector array. The detector array was translated along two orthogonal axes in the image plane of the receive channel objective lens using two computer-controlled motorized translation stages. This allowed for sub-pixel scanning, resulting in a composite image of the scene with improved spatial resolution. This paper presents preliminary measurements of depth and intensity profiles taken at stand-off distances of approximately 2.5 meters in laboratory conditions using average optical power levels in the micro-watt regime. A standard test chart was used to evaluate the resolving power of the system for both standard and micro-scanned images to assess performance improvements in spatial resolution. Depth profiles of targets were also obtained to investigate improvements in resolving small details and the quality of target edges.