Visible light waves from the sun travel in all directions. When this scattered light meets a horizontal surface, like a road or water, a large portion of the light is reflected with horizontal polarization. This horizontally polarized light is seen as white glare, and masks light that is useful to the human eye, reducing visibility. By using a sheet of vertical polarizing material, the horizontally-polarized component can be significantly attenuated, reducing the overall light level reaching the eye. This improves contrast, and thus the perception of the scene.
How Polarization Works
The sun’s rays reflect light in every direction, so when a ray hits a flat surface, the reflected light shines back at your eye and is magnified, causing glare. Glare is a real buzzkill. It reduces your depth perception, distorts your view and colour perception, and can even temporarily blind you. Not cool.
Regular sunglasses are designed to only reduce the amount of light that is transmitted through the lens horizontally and vertically. But the chemical filter on the lenses of polarized sunglasses is designed to absorb horizontal light waves, while still allowing vertical waves to pass through. Because light only travels in one direction through polarized lenses, glare is eliminated.
Though polarized sunglasses improve comfort and visibility, you will encounter some instances when these lenses may not be advisable. One example is downhill skiing, where you don’t want to block light reflecting off icy patches because this alerts skiers to hazards they are approaching.
In addition, polarized lenses may reduce the visibility of images produced by liquid crystal displays (LCDs) or light-emitting diode displays (LEDs) found on the dashboards of some cars or in other places such as the digital screens on automatic teller machines and self-service gas pumps.
Benefits of Wearing Polarized Lenses:
- Reduce Glare, Improve Safety
- Reduce Eyestrain
- Better Vision
- Best for people who play water sports
- Better Visual Contrast
Sunlight can be absorbed or reflected in several different directions. There are two meridians: horizontal and vertical. Commonly, the light coming from all direction (horizontal and vertical) create a problem (glare) for viewing due to multidimensional light. Due to more light entering into our eyes, we may have a blurred image. Polaroid cuts one dimensional or meridian light to enter our eyes and we see the sharp or clear image.
Uses of polarized glasses
- Driving (to decrease driving fatigue and increase driving safety)
- For fishing and boating
- For more visual comfort at beach
- To block UV radiation
- In snowy days
- More useful in bright light.
Facts about Polaroid glass
- Polaroid is not 3D glass.
- It can be made in prescription glass.
- Should not use for a computer or electronic devices.
- Should not use by pilots.
- Polarized lenses are available in different colours in the market, depending upon the material from which the lenses are made.
- Darker colours of polarized sunglasses provide higher levels of polarization.
About the author: Dipsikha Aryal, Patan Academy of Health Science