Temporal and Spatial Focusing in SPAD-Based Solid-State Pulsed Time-of-Flight Laser Range Imaging

Area of Science:

• Photonics and Optical Engineering
• 3-D Imaging Technologies
• Solid-State Detector Physics

Background:

• Single-photon avalanche diode (SPAD) detectors are crucial for pulsed time-of-flight (TOF) 3-D range imaging.
• Understanding the signal-to-noise ratio is vital for optimizing performance in varying light conditions.

Purpose of the Study:

• To analyze the relationship between signal and background noise in SPAD-based pulsed TOF 3-D imaging.
• To identify optimal strategies for enhancing measurement range and performance under challenging conditions.

Main Methods:

• Theoretical analysis of signal and noise in SPAD detectors operating in single-photon mode.
• Experimental validation using a 256-pixel solid-state pulsed TOF line profiler.
• Investigation of illumination strategies, including block-based and laser stripe illumination.

Main Results:

• Concentrating optical power into short, intensive pulses and spatial focusing improves performance.
• Block-based or laser stripe illumination is more advantageous than flood illumination for 3-D range imaging.
• A 256-pixel SPAD pulsed TOF line profiler achieved a 5-10 m range in bright sunlight with 260 µW average optical power.

Conclusions:

• Optimized illumination strategies significantly enhance the performance of SPAD-based pulsed TOF systems.
• The proposed design principles enable robust 3-D range imaging in challenging environments with low power consumption.