Unprecedented Timing Accuracy: 13 Picosecond Resolution
A key breakthrough in this system is its ability to measure the time taken for a laser pulse to travel to an object and return with an accuracy of approximately 13 picoseconds. A picosecond (ps) is one-trillionth of a second (1 ps = 10⁻¹² s), meaning the system can detect minute variations in depth at an incredibly fine scale. To put this precision in perspective, light travels just 3.9 millimeters in 13 picoseconds. This level of accuracy allows the system to distinguish between surfaces that are only millimeters apart, even at long distances.
The Role of SNSPDs: Ultra-Sensitive Quantum Detection
The system’s high precision is enabled by its superconducting nanowire single-photon detectors (SNSPDs). Unlike conventional avalanche photodiodes (APDs) used in many LiDAR systems, SNSPDs have almost zero dark noise, significantly enhancing detection in low-light conditions or through obscurants like smoke and fog.
However, these detectors must be cooled to 1 Kelvin (-272°C)—just above absolute zero—using a specially designed cryocooler. At this temperature, the nanowires become superconducting, meaning they exhibit zero electrical resistance. When even a single photon of light strikes the detector, it momentarily disrupts the superconducting state, creating a detectable signal. This extreme sensitivity allows the system to work efficiently with low-power laser pulses, making it both eye-safe and highly effective in daylight conditions.
Single-Photon Detectors in LiDAR Systems
Single-photon detection is not unique to this research but is a growing trend in advanced LiDAR applications. Many time-of-flight (ToF) LiDAR systems, particularly in automotive and defense sectors, utilize single-photon avalanche diodes (SPADs), which detect individual photons and convert them into electrical signals. However, SNSPDs offer superior time resolution and lower noise, making them ideal for long-range, high-precision applications like this one.
Future Applications: From Security to Geology
Beyond facial and activity recognition, this LiDAR system has potential applications in geological monitoring, such as detecting subtle movements in rock faces or buildings that could indicate structural instability. The researchers are now aiming to extend its range to 10 kilometers—potentially identifying vehicles, infrastructure, or other objects at extreme distances.
For more information on this research, please visit the article post on Heriot Watt University.
For more information about single photon detection, please visit our blog post titled, Airborne Single Photon Lidar Breakthrough.
We will be discussing single photon detection in more detail in the future, as it is an exciting technology (especially for long distance ranging) and an interesting intersection of lidar and quantum science. Please subscribe to our newsletter below so that you do not miss that content. Thanks for reading!
