Abstract:
Background: There has been a tenfold rise in the number of reported laser strikes onto aircraft during the last decade; over 90% of which being caused by green lasers. Laser strikes on aircraft can cause a number of hazardous conditions for the crew, passengers, and people on the ground. Eye damage, such as flash blindness, loss of night vision, retinal lesions, and temporary/permanent blindness may occur, not to mention the possibility of skin burns or even crash landings.
Aim: This study assessed the viability of a thin film coating, specifically design to absorb/reflect green laser light as a potential engineering control to protect the people on-board the aircraft. Three factors were tested for: the coatings ability to prevent green laser light transmission, magnitude of glare production, and magnitude of color distortion.
Methods: The light transmission of a green laser and a white light source through aircraft window test samples and a 532nm notch filter were measured by each light source’s photometric intensity, power level, and spectral graph. Photographs of green laser strikes upon aircraft window test samples and a 532nm notch filter were analyzed, via photographic software color histograms, comparing the magnitude of green light wavelengths to measure glare production. Photographs were also taken of various aircraft scenarios and a color reference card to analyze the magnitude of color distortion, via photographic software color histograms, of a white light source transmitting through aircraft window test samples and a 532nm notch filter.
Conclusions: Thin film coatings developed to absorb/reflect 532nm green laser light can be a very effective means to protect aircraft crews and passengers from the associated hazards of laser strikes. However, this engineering control is only most effective when the laser beam is normal to the coated aircraft window. As the angle of attack for the laser strike increases, the coating’s effectiveness decreases. However, there does seem to be a correlation between a decrease in light transmission and an increase in angle of attack. Yet, there does not seem to be a difference in the amount of light transmission between flat and curved window surfaces. Further research is needed to develop an engineering control designed to protect against laser strikes, such as the development of a plexi-glass coating, a comparative study of coated and uncoated glass and plexi-glass aircraft window samples, and the viability of coating designed to shift the laser light away from the visual spectrum.