Uses of polarisation

Prior knowledge needed:

• Polarised waves
• Polarisation

Uses of polarisation

There are a few different uses of polarisation in real life:

• Reducing glare from surfaces
• Improving contrast in LCD screens
• Reducing reflections in photography
• Polarised sunglasses
• (among many other things)

Reducing glare from surfaces

When light reflects off a flat surface (like water or a road), it becomes partially polarised. This means that the reflected light waves oscillate more in one direction than in others, which can create glare that makes it hard to see.

You can see this when looking at a wet road on a sunny day, or the surface of the ocean. If you’re standing at the right angle, the reflected light can be very bright and make it difficult to see anything else.

To reduce this glare, we can use polarising filters (like those in polarised sunglasses). These filters only allow light waves oscillating in a certain direction to pass through, blocking the rest. By aligning the filter to block the direction of the polarised reflected light, we can really reduce the glare and improve visibility.

Improving contrast in LCD screens

LCD screens are the most common type of screen you’ll see. Unless you have an OLED device, it’s probably an LCD screen.

They work by having a backlight that produces unpolarised light, to light up the different coloured pixels on the next layer of the screen.
This light then passes through polarising filters that stop certain directions of oscillation, allowing only light oscillating in a specific direction to pass through.

This helps improve the contrast of the screen, which helps with things like colour accuracy and viewing angles.

Polarised sunglasses

Polarised sunglasses are a type of sunglasses that have polarising filters built into them. This essentially makes them really good at reducing glare from surfaces like water, roads, and snow.

Only the light that you want to see (the light oscillating in the right direction) is allowed to pass through the lenses, while the rest is blocked.

This makes it much easier to see in bright conditions, and can also help reduce eye strain.