"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.

The protection device ( helmet-mounted special goggles containing four lenses) was developed under a $7.2 million contract managed by Aeronautical Systems Division at Wright-Patterson AFB, Ohio. The requirements for the goggles was orchestrated by Cal Crochet, SAC Life Support System program manager, who was the direct interface with Sandia Laboratories at Kirtland AFB, NM. The idea for the goggles came from Cal's experience during his early days of flying helicopter (1957) at Eniwetok Atoll during nuclear tests under "Operation Hardtack" and later from his experiences with the flash curtain, gold goggles and eye patch problems encountered as a SAC B-47 and B-52 aircraft commander with the 306th and 509th Bomb Wings... What initially was a visor lens for B-52 pilots was later refined into glass that fit entirely within the viewing ports of an airplane cockpit, with 6-in. diameter shutters in the viewing windows.

The original PLZT goggles, military designation EEU-2/P, were developed for nuclear bombers such as the B-52 and B-1 in the Strategic Air Command (SAC), where the crew members would hopefully be just outside the blast, radiation, and/or heat damage radius of the weapon. A later version was designated EEU-2A/P, the difference between them being that the EEU-2A/P changes to dark faster than the EEU-2/P. By 2003 Thermal Flash Protective Devices (TFPD) were required for all PACAF aircrews on SIOP missions. Either the MIL-G-635 or PLZT goggles at the wing commanders discretion would satisfy requirements for TFPD. On aircraft that were PLZT modified, it was recommended that the PLZT goggles be used."