What does polarized light really mean?

Have you ever tried reading a message on your phone while wearing sunglasses? That annoying checkerboard pattern is the result of polarized light. Just like you rely on your cellphone for everyday use, pilots rely on their LCD flight monitors for a safe and successful flight. With polarized glasses, these displays are difficult if not impossible to read. So what exactly does polarized light mean?

Light is made up of waves going in a specific directional field. Since the sun is not polarized, the directions are scattered with no uniform trajectory. When light is reflected off of a surface, such as water, it becomes polarized, meaning all the light is in one directional field. Polarized sunglasses have a coating called a polarizer, which filters light into a specific direction before it reaches your eye.

So why aren't all glasses polarized if they reduce glare and increase visibility? LCD screens found on smartphones, televisions and many monitors are also constructed with polarized filters, and viewing these through polarized sunglasses creates distortion. This means that the light emitted off of the LCD screen is polarized and emitted out horizontally. Consequently, LCD screens are often difficult or impossible to read while wearing polarized glasses, which can be problematic.

This is why pilots who depend on their LCD monitors for their primary flying instruments, such as their navigation display and other essential gauges, would not be able to see these displays clearly with polarized lenses. Additionally, cockpit windows are often partially polarized. When polarized sunglasses are worn, dark oily patches are commonly seen when looking through the airplane's window, severely reducing visibility and posing safety risks.

Method Seven nonpolarized sunglasses have an anti-glare coating that allows for a crisp LCD display without obstructive sun glare. This will enable you to view your iPhone, GPS, or instrument panel with perfect clarity while safeguarding your eyes from harmful glare. Polarized sunglasses may offer adequate protection at the beach, but if you're depending on your eyes to see your instrument panel in-flight, nonpolarized lenses are a safer option with better clarity.