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In the smart glasses the images are projected on glass. But they are still clear to eyes.

We usually can't see something clearly at such close distance. Then, how is the image projected from a small screen on the glass?

Can someone explain how it works in actual smart glasses also how it can be possible if I want to project a screen(not so small, small oled ones) on a glass making it visible to close distance?

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When you project an image on a reflective medium, you inherit the projection distance. So what you are seing is a plane that is hovering behind the glass. In essence your eyes see is the whole path to the target as if it never had reflected at all.

So no need to focus that close.

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  • $\begingroup$ More to the point: the projection system uses lenses to place the virtual object at sufficient distance that the eye easily focusses the final image onto the retina $\endgroup$ Sep 16, 2021 at 14:40
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    $\begingroup$ @CarlWitthoft possibly, or wave guides, concave mirrors etc. In anycase eyes dont actually focus to the distance but the apparent distance of incomming rays. $\endgroup$
    – joojaa
    Sep 16, 2021 at 15:05

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