# Electrically Adjustable Bifocals

**URL:** <https://boards.straightdope.com/t/electrically-adjustable-bifocals/351717>\
**Category:** Miscellaneous and Personal Stuff I Must Share\
**Created:** [April 7, 2006, 2:17pm UTC](https://boards.straightdope.com/t/electrically-adjustable-bifocals/351717 "2006-04-07T14:17:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [April 7, 2006, 2:17pm UTC](https://boards.straightdope.com/t/electrically-adjustable-bifocals/351717/1 "2006-04-07T14:17:34Z")

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[It’s about time someone invented these:](http://www.physicsweb.org/articles/news/10/4/2/1)

> [@](#):
>
> a layer of liquid crystal sandwiched between two glass surfaces, the focusing power of which can be changed by altering the voltage applied to the lens. Although the lens has to be manually switched on and off to change focus, the researchers say the work could lead to lenses that automatically adjust their focus depending on where the user is looking  
> …  
> It consists of a flat, 5-micron thick layer of liquid crystal sandwiched between two layers of glass that are coated with concentric rings of tiny, transparent indium-tin-oxide electrodes.  
> …  
> applying a voltage of less than 2V to the electrodes changes the orientation of the liquid-crystal molecules

They’re [very fashionable looking too](http://www.physicsweb.org/articles/news/10/4/2/1/060402)🆒😉

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**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\
**Post date:** [April 7, 2006, 2:35pm UTC](https://boards.straightdope.com/t/electrically-adjustable-bifocals/351717/2 "2006-04-07T14:35:16Z")

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I’ve seen lots of switchable prototype eyewear over the years (although not bifocals before), and they usually suffered from being too fragile. we’re closing in on more robust architectures, but the last switchable lenses I got my hands on started changing if I touched the actual lenses.