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Pranks related to laser pointer attacks on aircrafts, landing or taking off from airports, is a risky affair. The sudden flashes of bright light often incapacitate the pilot, making them blind for seconds thus increasing the chances of a major accident. According to the Federal Aviation Administration (FAA), 6754 laser strikes on aircraft were reported in 2017. And since the attacks happen with different colored lasers, such as red, green or even blue, scientists have had a difficult time developing a single method to impede all wavelengths of laser light in order to curb the affects of laser beam flashing.

But in a recent new finding, researchers have reported of liquid crystals that could someday be incorporated into aircraft windshields to block any color of bright, focused light. The result was presented at the American Chemical Society (ACS) Spring 2019 National Meeting & Exposition. According to Jason Keleher, PhD at Lewis University and the project’s principal investigator, they were approached by collaborators in the aviation department at Lewis university about the growing problem happening at airports across the world, where people were shooting lasers at planes during takeoff and landing, the critical phases of flight.

Such attacks, which cause bright flashes of light in the cockpit, can distract pilots or inflict temporary or permanent visual damage, depending on the wavelength and intensity of the laser. According to Daniel Maurer, an undergraduate student and member of the project team, the researchers wanted to come up with a solution that didn’t require complete re-engineering of the aircraft’s windshield, but instead add a layer to the glass that harnesses the existing power system for windshield defrosting.

Rather than being integrated into the windshield, previous approaches have included pull-down windscreens or goggles that pilots don during takeoff and landing. However, these can be inconvenient because they require the flight crew to take these precautions whether or not they are actually being targeted. An even bigger problem is that these strategies work only for specific wavelengths of laser light. They don’t block everything. They’re usually targeted toward green lasers because those are used for the majority of the attacks, says Maurer.

To develop their new approach, the researchers took advantage of liquid crystals –– materials with properties between those of liquids and solid crystals that make them useful in electronic displays. The team placed a solution of liquid crystals called N-(4-methoxybenzylidene)-4-butylaniline (MBBA) between two 1-inch-square panes of glass. MBBA has a transparent liquid phase and an opaque crystalline phase that scatters light. By applying a voltage to the apparatus, the researchers caused the crystals to align with the electrical field and undergo a phase change to the more solid crystalline state. The aligned crystals blocked up to 95 percent of red, blue and green beams, through a combination of light scattering, absorption of the laser’s energy and cross-polarization. The liquid crystals could block lasers of different powers, simulating various distances of illumination, as well as light shone at different angles onto the glass.

In addition, the system was fully automatic: A photoresistor detected laser light and then triggered the power system to apply the voltage. When the beam was removed, the system turned off the power, and the liquid crystals returned to their transparent, liquid state. The researchers only want to block the spot where the laser is hitting the windshield and then have it quickly go back to normal after the laser is gone. The rest of the windshield, which was not hit by the laser, would remain transparent at all times.

Now that the researchers have shown that their approach works, they plan to scale it up from 1-inch squares to the size of an entire aircraft windshield. Initial results have shown that a sensor grid pattern on 2-inch squares of glass will respond only to the section of glass that is illuminated. The team is also 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.

The researchers acknowledged support and funding from Southwest Airlines, the Aviation and Transportation Department at Lewis University and the Colonel Stephen S. and Lyla Doherty Center for Aviation and Health Research.