Researchers at Heriot-Watt University in Edinburgh, Scotland have developed a new laser power camera system which is capable of taking high-resolution 3D image of the objects from a distance up to a kilometer away.
The technology behind this innovation is what we called time-of-flight (ToF) navigation systems for autonomous vehicles, and other applications, but the main problem behind this technology is that many current systems offer relatively short range and at the same time they failed to image objects that do not reflect laser light. The researchers also encountered this problem during the development, but they luckily tackled these limitations by using a new ToF imaging system that can gather high-resolution, 3-D information about objects that are typically very difficult to image, from up to a kilometer away.
The new ToF imaging system works by sweeping a low-power infrared laser beam rapidly over an object. It records, pixel-by-pixel, the round-trip flight time of the photons in the beam as they bounce off the object and arrive back at the source. The system can resolve depth on the millimeter scale over long distances using a detector that can “count” individual photons.
According to Aongus McCarthy, the first author of the study:
The ability of the new system to image objects like items of clothing that do not easily reflect laser pulses makes it useful in a wider variety of field situations. Our approach gives a low-power route to the depth imaging of ordinary, small targets at very long range.
Whilst it is possible that other depth-ranging techniques will match or out-perform some characteristics of these measurements, this single-photon counting approach gives a unique trade-off between depth resolution, range, data-acquisition time, and laser-power levels.
The primary use of the system is likely to be scanning static, human-made targets, such as vehicles. With some modifications to the image-processing software, it could also determine their speed and direction.
One of the key characteristics of the system is the long wavelength of laser light the researchers chose. The light has a wavelength of 1,560 nanometers, meaning it is longer, or “redder,” than visible light. This long-wavelength light travels more easily through the atmosphere, is not drowned out by sunlight, and is safe for eyes at low power.
The research team was led by Gerald Buller, professor at Heriot-Watt University in Edinburgh, Scotland, and the research thesis has been published in Journal Optics Express.