To see unseen: EO sensors strengthen navies' compound defenses

March 02, 2023

Electro-optical sensors

Electro-optical (EO) sensors provide a plethora of benefits in military environments, such as better situational awareness, more accurate classifications, reduced personnel needs and more mission recording options. But perhaps the strongest ace in the hole is that EO sensors work ‘passively’, in that they don’t send out any signals that could possibly be detected by external parties. For navies this means that EO sensors help them to see, but remain unseen. A vital feature in today’s combat environment, especially looking at future threats. We interviewed Didier Flottes and Franck Maarse, two Naval operational experts well versed in naval electro-optical sensors , about the importance of EO in naval combat and security operations and what the future holds in store.

First things first: what are electro-optical sensors?

“Essentially, electro-optical (EO) sensors measure physical quantities and characteristics of light, then convert that into electronic data. When we talk about it in the naval domain, we usually explain it as the sensors that expand on what you would be able to do with your own eyes. EO-sensors are types of cameras that simply help you to see more, or further, or in more detail than you would be able to do yourself. With help of latest technologies, smart algorithms can be applied to EO-sensor data, to make their 24/7 surveillance information even more valuable for navies and their mission.”

Doesn’t radar usually cover surveillance?

“Certainly, but radar covers different types of surveillance, with different technique. Radars send out radio waves. Based on what reflects back, they can determine range, bearing, altitude and speed (4D radar like NS50) of something it detects. Depending on the type of radar and your software, it can learn to detect, track and classify targets based on those characteristics. But radar cannot ‘see’ and identify in the way EO sensors can. For example, if your radar is detecting an approaching group of boats in a very busy sea lane, EO will provide the additional info of being able to see what the boats actually look like because of infrared and daylight camera sensor data. It will help confirm whether it’s a group of fishermen or pirates –crucial for identification next to range, bearing, and speed measurements measurements.

More importantly: radars are active sensors. This means that they actively emit signals to be able to detect something – and whatever they are emitting, someone else may pick up. This may be fine in friendly waters and during peaceful missions. In hostile environments however, it may give away your position. Even worse, it might make you a target. In those situations, you want to use your radar sparingly to remain undetected. EO sensors are passive: they only gather information and do not emit any signals themselves. This means their use cannot be detected. In an ever-changing world filled with conventional to asymmetrical threats, a sophisticated EO capability might give you the edge you need to successfully complete your mission.”

In what types of missions is EO especially useful?

“Our naval threat landscape is changing rapidly. Missiles are faster than ever, yet we’ve now also got slow moving UXV’s to keep in mind. Asymmetric threats are becoming more and more standard practice. You need to be able to detect, classify and identify as fast as you can, so you have more reaction time. A few more seconds may make the difference.

Navies need to be ready for the threats of today and tomorrow, which means you cannot rely on a single source of data. Ideally, you want to combine data of multiple sensors that expand on and confirm findings, so you can act faster and more efficiently. By combining sensor data from for instance radar and EO, everything that is happening around your naval ship becomes exponentially clearer.

EO is exceptionally useful in situations where you need to better classify objects on or just above the surface from close to medium range threats – something our Gatekeeper sensor specializes in. Long range EO sensors (such as ARTEMIS) can help you see and identify such a target even before it appears on the horizon for radar detection. Having a few extra seconds to react could greatly improve survivability of the ship and crew.

For different reasons, you can’t always have people on deck or on the lookout – even if the weather is on your side and visibility is high. EO-sensors help you to better carry out 24/7 close-range surveillance around the ship in any condition. EO-sensors are not just about low, fast targets, they also help identify slow, small surface targets, and anything coming close to your vessel (such as small boats and even lurking periscopes). Perhaps your radar will have noticed a small boat coming towards you, but you don’t know what kind it is. Just let Gatekeeper become your ‘eyes’, so you can digitally zoom in, look for flags, numbers, colours, and other identifying characteristics.

Drone detection, for instance UAV’s and USV’s, also becomes much easier to find and classify. A swarm of drones can emit waves that are hard to classify for traditional radars. Your on-board daylight and/or infrared cameras will help you detect, follow, identify and confirm what your other sensors are looking at. This is very valuable, not just in keeping your crew safe, but also in protecting your multi-million-euro ship against very expendable USVs and UAV’s that are cheap to replace.

Additionally, and perhaps somewhat overlooked, is that good EO-sensors are also valuable during boarding operations at sea for legal and for safety purposes. Your crew can be at risk when boarding a suspect vessel, and your onboard Gatekeeper cameras will help you keep an eye on what is happening on that neighbouring deck. Remember: you can also record whatever your Gatekeeper sees, so you can build an archive of potentially important legal evidence. Gatekeeper even has its use when docked in a foreign harbour: you need one single active operator at a time to keep watch on and around the ship, even at night. Resulting in more efficiency of time (crew can perform other important tasks) and a better rested crew.”

How are you keeping Thales’ EO solutions futureproof?

“Next to hardware improvements – for instance, we’re developing a Gatekeeper update that will include improved camera hardware – we’re always working on smarter integration, better interfaces and the best, operator friendly software that ties everything together. We’re looking into a lot of new objectives: automated detection of objects and human identification, clutter rejection, reduce operator workload and more. Threats are becoming increasingly fast, strong, small, harder to detect, so we will keep building solutions that not only keep up, but are ahead of the game. Control of information will be always be paramount: the more sensors you can integrate, the better, to combine and confirm findings.

The future of EO will definitely move towards EO suites where multiple sensors and the CMS work together in the most efficient way, with help of A.I. based algorithms. They’ll be able to quickly process the EO data and alert the crew on a ship in case of approaching threats via the CMS. Such a relation would enable fast detection, tracking, classification, and engagement capabilities against, for instance, the evolving USV and UAV threats as seen in the current conflict climate.

We’re also responding to the need for sensors that are open to receive frequent software updates that are backwards compatible, through a continuous improvement and service program between industry and navies. Thales has extensive experience in continuously improving its product portfolio and integration of sensors with a ship’s CMS. European navies such as Germany, the UK and Netherlands, as well Mexico, benefit from integrated mission systems including EO sensors. EO is only going to become more important in the near future.”