Title. I mean I can’t be the first one who thought of this. A filter on your phone so that you don’t need to wear glasses to read or view pictures would be awesome.
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your head moves relative to your screen. If the prescription was built into your phone, it would only work from a specific angle. And your eyes have different prescriptions, so even then it would probably only work for 1 eye.
People haven’t thought of that because it wouldn’t work. People who need glasses have a problem with their lenses such that they are not making sure light falling on one patch of the retina only comes from one direction. The result is blurry vision. There is no way to twist around the display on a smartphone that would solve this problem because they still cannot ensure only light from one part of the display hits a particular part of their retina.
As for people who can see clearly at short distance but longer distances are blurry, they can still view the smartphone screen clearly. There is no filter required as the normal images passed through the smartphone are viewable. They are using the lens of the smartphone to view distant things.
Yay optics!
So your eyes are built like cameras using two parts: a lens and a detector (your retina). Now, the goal is to have your lens focus a clear image of what you’re looking at exactly on your retina. If, unfortunately, your eye is a bit weirdly shaped, the spot where the image is focused is not on your retina: you see an unfocused =blurry image. This means that instead of a small section of the image hitting exactly one of your retina cells, you have multiple sections hitting multiple cells and generating a very blurry picture. Depending on your eye problem, you may struggle to focus images that are far away, or images that are close to you. In any case, you’re going to use glasses that will help with focusing the image on your retina by adjusting your lens. That’s the critical part. If you hold your glasses away, you won’t see clearly just in the small square. Everything will be blurry because the images aren’t focused on your retina anymore.
In this way, you cannot have a glasses app, since your phone won’t be able to project the images directly focused on your retina. Instead, you’ll see a blurry image even more blurred.
Such filter is impossible on the current displays.
To create such a filter, the display must send a different light in different directions. Current displays send the same light in all directions.
In theory, this can be achieved with a [phased array](https://en.wikipedia.org/wiki/Phased_array), but as far as I know, optical phased arrays are very difficult to make – putting one in a phone is beyond our current technology.
I wrongly though when I got my VR headset that I wouldn’t need to wear my glasses when I played because they were literally sitting on my face. Man, I was sorely disappointed.
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