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How does light in a virtual reality headset work

How does light in a virtual reality headset work?

Tuesday 02 November 2021

Many technology-fearing films from the 1990s projected that virtual-reality technologies would become a daily part of our lives and would inform wide societal changes. While we certainly have not reached that point, last week’s rebrand of the Facebook multinational corporation, which accounts for its designs on shaping future VR technologies, indicated that this will be a very hot topic for the next decade.

But how do these technologies work? How does a headset show you something that isn’t there?

Bending light inside VR headsets

Virtual reality headsets shape a virtual world around you by projecting two slightly different screens in front of you, which you can see through two lenses. The different angles between the two lenses allow you to see a 3D environment using only a flat 2D screen. These screens are similar to other LCD screens you see all over the place, such as on televisions or smartphones, and they are lit by a light source behind the screen.

This means that your eyes are very close to the screen, and the lenses bend the light emitted, making it look as though the world around you is further away than it is. This gives the level of depth required for your mind to believe you really are inside a virtual environment. This is then typically combined with gyroscopic sensors, which allow the screen to synchronise movements with your head, to movements in the virtual world. While amazing, there are numerous accounts of headaches when people start using VR technology, and this sadly has caused problems for some people.

The Problems with VR technologies

VR technologies are still in relative infancy, compared to other technical media and this means that the consoles are still struggling with a few growing pains. Firstly, many experience headaches, even after a limited initial time inside a virtual environment. This is because our eyes are straining to focus on details that are very close to our faces, and the lens calibration must be done very carefully.

Secondly, the LCD screens inside VR units are typically built using white LEDs, but these can have a high concentration of blue light. This will exacerbate headaches, as well as disturb your circadian rhythms. Some even have concerns that extended use might result in damage to the retina, and an increased risk of macular degeneration. However, these negatives should be taken with a pinch of salt, as the technology is so new that extended trials are not yet robust enough to provide a meaningful indication as to the risks associated.

A Bright Future?... Maybe

The fact is virtual reality still has a long way to go before it becomes a widely accepted technology like the smartphone, tablet, and laptop. However, VR is striding into the future with mesmerising rapidity. What looked impossible to achieve ten years ago may in fact be just around the corner.

While it will remain a technology on the fringe of the average consciousness for now, we hope that the health of its users’ eyes is prioritised as the exciting new devices continue to be developed and released in the coming years.


  1. YouTube.
  2. VR Lens Lab.
  3. BBC.
  4. NHS.


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