Uses of polarisation
Prior knowledge needed:
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.
flashcards
| Question | Answer |
|---|---|
| Question / Key Term | Answer / Definition |
| What happens to light when it reflects off a flat surface like water or a road? | It becomes partially polarised, meaning the reflected light waves oscillate more in one direction than others, creating glare. |
| How can glare from reflected light be reduced? | By using polarising filters (e.g., in polarised sunglasses) that only allow light waves oscillating in a certain direction to pass through, blocking the polarised reflected light. |
| How do LCD screens use polarisation to improve contrast? | An LCD screen has a backlight that produces unpolarised light. This light passes through polarising filters that stop certain directions of oscillation, allowing only light oscillating in a specific direction to pass through, improving contrast and viewing angles. |
| What is the main benefit of polarised sunglasses? | They reduce glare from surfaces like water, roads, and snow by only allowing light oscillating in the right direction to pass through, making it easier to see in bright conditions and reducing eye strain. |
| What prior knowledge is needed for understanding uses of polarisation? | Polarised waves and Polarisation. |
| What are four real-life uses of polarisation listed in the note? | Reducing glare from surfaces, improving contrast in LCD screens, reducing reflections in photography, and polarised sunglasses. |
| How does reducing glare from surfaces improve visibility? | By blocking the direction of polarised reflected light (e.g., from a wet road or ocean surface), the glare is reduced, making it easier to see other things. |