The Time-Correlated Single-Photon Counting (TCSPC) technique has emerged as a
candidate approach for Light Detection and Ranging (LiDAR) and active depth imaging
applications. The work of this Thesis concentrates on the development and
investigation of functional TCSPC-based long-range scanning time-of-flight (TOF)
depth imaging systems. Although these systems have several different configurations
and functions, all can facilitate depth profiling of remote targets at low light levels and
with good surface-to-surface depth resolution. Firstly, a Superconducting Nanowire
Single-Photon Detector (SNSPD) and an InGaAs/InP Single-Photon Avalanche Diode
(SPAD) module were employed for developing kilometre-range TOF depth imaging
systems at wavelengths of ~1550 nm. Secondly, a TOF depth imaging system at a
wavelength of 817 nm that incorporated a Complementary Metal-Oxide-Semiconductor
(CMOS) 32×32 Si-SPAD detector array was developed. This system was used with
structured illumination to examine the potential for covert, eye-safe and high-speed
depth imaging. In order to improve the light coupling efficiency onto the detectors, the
arrayed CMOS Si-SPAD detector chips were integrated with microlens arrays using
flip-chip bonding technology. This approach led to the improvement in the fill factor by
up to a factor of 15. Thirdly, a multispectral TCSPC-based full-waveform LiDAR
system was developed using a tunable broadband pulsed supercontinuum laser source
which can provide simultaneous multispectral illumination, at wavelengths of 531, 570,
670 and ~780 nm. The investigated multispectral reflectance data on a tree was used to
provide the determination of physiological parameters as a function of the tree depth
profile relating to biomass and foliage photosynthetic efficiency. Fourthly, depth
images were estimated using spatial correlation techniques in order to reduce the
aggregate number of photon required for depth reconstruction with low error. A depth
imaging system was characterised and re-configured to reduce the effects of scintillation
due to atmospheric turbulence. In addition, depth images were analysed in terms of
spatial and depth resolution
