Tyler Rogoway
During a nuclear exchange, as B-52H and B-2A pilots make their way to and from their targets, flashes from nuclear detonations would have the ability to temporarily blind them, making flying their aircraft impossible. This intermittent blindness could last two minutes during the day, or up to ten minutes at night. Different countermeasures were developed during the Cold War to counter this physiological reality. These included constructing thermal curtains to cover the B-52s windows, along with a television camera and FLIR system that, along with the BUFFs instruments, allow pilots to continue on their mission without external visibility. Polarized Lead Zirconium Titanate (PLZT, pronounced "plizzit") flash blindness goggles are also used for the same purpose, and they look as otherworldly as can be.
PLZT goggles attach to the pilots helmet and are interfaced with a igloo cooler-like control and power supply unit (see the whole system here). The system works to detect dramatic and fast changes in light. When that a happens, a circuit is broken. This triggers the goggles to quickly turn opaque. Once the light has returned to normal the goggles will turn translucent again. Flightgear.dk does a great job at describing this unique and somewhat obscure system and its genesis in great detail:
"The most advanced thermal flash protective devices in use are the PLZT goggles. These goggles are made of sandwich composite of polarized glass with an inner layer of a transparent electro-optic ceramic called PLZT. When linked to an electric current, the lenses are clear. But any dangerous flash of light, such as lightning or a nuclear blast, instantaneously breaks the circuit. This causes the lenses to go black, protecting the vision of anyone wearing the helmet. The designers of the PLZT goggle had found that the material could be discharged quicker than when charged to change the transmittance. Unfortunately, in order to obtain the desired switching speed, this meant that when the nuclear flash protective goggle failed, it was basically opaque.
PLZT is a ceramic material consisting of lead, lanthanum, zirconate, and titante and it can be electronically switched rapidly in polarity, such that when sandwiched with a near infrared blocking material and a fixed polarizing material, the visual transmittance can be varied from full open state (approximately 20%) to totally opaque within a ten-millionth of a second.
https://www.yahoo.com/news/usaf-bomber-pilots-wear-during-233854276.html
