Assessing Potential Laser Strike Protection Engineering Control for United States Coast Guard Aircraft

Thesis (Master's)--University of Washington, 2016-06

Background: There has been a tenfold rise in the number of reported laser strikes onto aircraft during the last decade; over 90% of which were 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, or 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: the coatings ability to prevent green laser light transmission, the magnitude of glare production, and the 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 irradiance, radiant power, and light spectrum. 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 of various aircraft scenarios and a color reference card were used to analyze the magnitude of color distortion via photographic software color histograms of a white light source transmitting through the test samples and a 532nm notch filter. Conclusions: Thin film coatings developed to 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 most effective when the laser beam is normal to the coated aircraft window. As the angle of incidence for the laser strike increases, the coating’s effectiveness decreases. The thin film coating is also very effective in creating almost no glare when the laser beam is normal to the coated aircraft window, but produces a larger glare as the angle of incidence increases. Lastly, as the thin film coating reflects green light, it does not appear to greatly distort red and blue light intensities. Further research is needed to develop an engineering control designed to protect against laser strikes, such as a plexi-glass coating that can to shift the laser light away from the visual spectrum.