Liquid crystals could stop laser attacks against passenger jets

Shining lasers at landing aircraft has become a potentially dangerous pursuit, but a new liquid crystal material could help reflect the blinding beams.

While we tend to think of drones as causing the greatest disruption to airports, another activity that has been ‘flying under the radar’ is shining laser pens at the cockpits of landing aircraft. The resulting flash of light is enough to incapacitate the pilot, potentially putting the lives of everyone on board at risk.

The US Federal Aviation Administration estimated that there were almost 6,800 incidents in 2017 alone, with pilots at Derry Airport being subjected to the beams of laser pens last year. Now, in an effort to prevent these beams from causing any harm, researchers have presented the creation of liquid crystals that could some day be incorporated into aircraft windshields to block any colour of bright, focused light.

To be revealed at the American Chemical Society’s annual meeting, the new liquid crystals could help overcome one of the biggest obstacles to tackling the problem: trying to protect against different-coloured lasers. Previous attempts to block the beams have been limited to pull-down windscreens or goggles. However, they were typically only capable of blocking out the green light that made up the majority of attacks.

To develop this new approach, the researchers from Lewis University in the US placed a solution of liquid crystals dubbed MBBA between two 1in-square panes of glass. MBBA has a transparent liquid phase and an opaque crystalline phase that scatters light, and when voltage was applied the crystals aligned with the electrical field to undergo a change to a more solid crystalline state.

In this state, the glass could block up to 95pc of red, blue and green beams through a combination of light scattering, absorption of the laser’s energy and cross-polarisation. This also allowed it to block out lasers of different powers and at a multitude of different angles.

Perhaps most importantly, the system is fully automatic and is only triggered in the spot where it detects laser light. Afterwards, it would return to normal, all while the rest of the glass would remain transparent.

Now that the researchers know it can work, they hope to scale it up to the size of an aircraft windshield, as well as testing different types of liquid crystals to find even more efficient and versatile ones that return to the transparent state more quickly once the laser is removed.