Crews of navy ships could one day be able to locate distant small aerial targets and threats flying just above the waves by detecting single photons of light.

A single-photon avalanche diode (SPAD) is an extremely sensitive sensor that works at the level of the individual particle and has the potential to overcome the challenge of picking out small targets amid the ocean waves, like a small uninhabited aerial vehicle or a missile flying just above the surface of the water.

Dr Dennis Delic, of the Defence Science and Technology Group, is leading the design, development and commercialisation of SPADs within Defence.

“With a normal camera, like your phone’s camera – those sorts of sensors rely on using lots of photons to form an image; in fact, they need millions of photons,” he said.

“With this miniature smart-sensor technology, we’re operating at the fundamental limit, detecting individual photons and registering each particle.

“Using advanced processing, we can count them and time them, and that opens up all sorts of opportunities in terms of what we can do.”

SPADs can be used to build up 3D images in low-light conditions or even when an object of interest is partially obscured. 

This revolutionary technology has a wide range of potential uses – both military and civilian – from finding objects underwater to tracking objects moving through space.

Another significant advantage of this technology for military operators is that using a SPAD as part of an active sensor system – that is, a system which is emitting energy that could be detected by an adversary – would reduce the risk of the user being targeted when they switch it on because of the reduced power required.

Dr Delic said using a SPAD as the detector in a LiDAR system, which measures distances by illuminating objects with light from a laser and then detecting the reflected energy, would considerably reduce the power needed because of the SPAD’s ability to function at very low photon levels.

He said the wider adoption of SPADs was expected to be far-reaching, with benefits flowing through to the design of wearable augmented reality vision sensors, autonomous vehicle navigation systems and advanced medical imaging capabilities, among many other possible applications.

Dr Delic has used an innovative design approach that reduces the cost of sensor production, paving the way for cost-effective manufacturing at scale.

“Combined with new integrated circuit design techniques, this represents the next revolution in quantum imaging, allowing us to see things that are normally hidden from view,” he said.

A crucial element of the research effort has been the collaborations with partners.

“Through partnering with academia, industry and the ADF, the adoption of SPAD sensor technology is the key to enhancing advanced demonstrator programs,” Dr Delic said.

“Ultimately, this will help protect Australian military personnel.”

Dr Delic was last year named as a finalist for the ANSTO Eureka Prize for Innovative Use of Technology in recognition of his work developing SPADs.