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Anti-theft sunglasses

Grind electrochromic lenses, stir in security features
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So, it seems that electrochromic sunglasses have been thought of and discussed on the Bakery since at least as early as 2001. Doing some research online, however, reveals a disappointing lack of vision (*snigger) in the development of them thus far.

Everyone knows expensive sunglasses are high-theft items. They have a nasty tendency of just... disappearing, in ways that cheapos don't seem to suffer from. Well, advances in size reduction of certain technologies over the last two decades seem to offer us a way to mitigate this problem. With the inclusion of some sort of biometric sensor, like a fingerprint or iris scanner, and a simple wear detection sensor, they could be programmed to go completely opaque when removed, resuming transparency only when unlocked with the owner's biometrics. Alternatively, for those who are understandably wary of providing their biometric data, Bluetooth tech provides a similarly convenient security option. By pairing it with a phone or smart watch, it could be set to go opaque if it becomes disconnected from the paired device, requiring a passkey to be entered on said device to unlock them later.

21 Quest, Mar 31 2021

You'd think not https://www.youtube...watch?v=JWLti-oVwuw
[Skewed, Mar 31 2021]

Like this? https://www.cntrave...-rooms-in-the-world
Osaka Capsule Inn [Skewed, Apr 01 2021]

[link]






       A low-tech alternative would be to have the sunglasses having two layers of perpendicular polarisation (horizontal and vertical) and a removable polarisation layer with polarisation at 45º that slips in the gap between the two layers. With all three polarisation layers, 50% of light can get through; with the removable layer removed, no light can get through.   

       To secure the sunglasses, just remove the intermediate layer and keep in a separate location (e.g. in your wallet).   

       Alternatively (and much more secure), the removable intermediate layer could be a 'coded' array of different refractive index areas (with front and back layer of the glasses correspondingly coded with refractive index areas). Without the intermediate layer the image through the sunglasses would fuzzy/garbled; with the intermediate layer the image through the lens would be clear.
xaviergisz, Mar 31 2021
  

       //So, it seems that electrochromic sunglasses have been thought of and discussed on the Bakery since at least as early as 2001//   

       Haven't they existed since the 90's or before?   

       [Goes away to look]
Skewed, Mar 31 2021
  

       [Wanders back]   

       Meh, can't be bothered to look any more, Google smart glass has been around since 2011 but I'm sure I remember some TV news pieces on wannabe cyber types & their home brew versions from way before that,
Skewed, Mar 31 2021
  

       Why not have them not-go-opaque, it unnecessarily alerts the thief to the fact they've built in security, instead think 'internet of things', go with GPS or phone mast tracking & upload what they see when they wear them to the cloud instead.   

       Leave the Zaphod anti fear effect as a manual feature you activate when the police or owner challenges them.
Skewed, Mar 31 2021
  

       //sunglasses having two layers of perpendicular polarisation (horizontal and vertical) and a removable polarisation layer with polarisation at 45º that slips in the gap between the two layers. With all three polarisation layers, 50% of light can get through; with the removable layer removed, no light can get through.//   

       This would be a very elegant solution, except polarizing filters really don't work like that. A horizontal polarizing filter is just a grid of fine black horizontal lines, light wobbling in the vertical orientation just gets absorbed. A polarizing filter doesn't CONVERT light TO one polarity, it just absorbs everything else. So your glasses would just be opaque, horizontal polarizer absorbs the vertically polarized light the vertical polarizer absorbs the remaining horizontally polarized light, the 45 degree filter wouldn't have much effect.   

       There are optics to do clever things with polarization, you can get beam splitters which will transmit one polarity and reflect another, and things like Wollaston prisms that create two diverging opposite polarized beams from an unpolarized input.
bs0u0155, Mar 31 2021
  

       I don't know if GPS tracking chips, and the required power source, can be made small enough to fit unobtrusively on a pair of sunglasses.
21 Quest, Mar 31 2021
  

       The problem with removable polarized filters is that they aren't the best option for security. Anyone can steal the sunglasses, and simply order replacement filters from the company. Before long there would be knockoff filters available on eBay and Amazon, so even the company's attempts to verify ownership would be got around too readily. Plus there's the inconvenience factor, of having to remove two of these things (probably about as difficult to reinsert as contact lenses), and the risk of losing or damaging the filters. If the idea is to solve the problem of sunglasses walking away, having a mechanism involving even more easily lost components than the sunglasses themselves seems counterproductive.
21 Quest, Mar 31 2021
  

       //This would be a very elegant solution, except polarizing filters really don't work like that. A horizontal polarizing filter is just a grid of fine black horizontal lines, light wobbling in the vertical orientation just gets absorbed. A polarizing filter doesn't CONVERT light TO one polarity, it just absorbs everything else. So your glasses would just be opaque, horizontal polarizer absorbs the vertically polarized light the vertical polarizer absorbs the remaining horizontally polarized light, the 45 degree filter wouldn't have much effect.//   

       Do a Google search for Malus' Law or three-polariser experiment. A bit counter-intuitive at first but you get a better understanding of polarizing filters.
xaviergisz, Mar 31 2021
  

       //I don't know if GPS tracking chips, and the required power source, can be made small enough to fit unobtrusively on a pair of sunglasses//   

       You'd think not <link> wouldn't you.   

       But a bunch of people at Sony, Google & Samsung think otherwise, at least for the wireless signal tracking with cell phone masts option, if they think they can actually fit a wireless transmitter in a contact lens then I'm pretty sure we can already get it into a pair of glasses, as it happens they must think they can get chips into contact lenses as well so.. [shrugs].   

       If they think can fit all that into a contact lens (including a transmitter for their image capture) then I'm very sure we can already fit everything the glasses need into it's arms & frame.   

       Power is a problem, you can get pretty small batteries but they'll still run out sooner or later, probably need the internet of things to be more ubiquitous (if that ever happens) so it can piggy back it's power off that, it's broadcast baby.
Skewed, Mar 31 2021
  

       //This would be a very elegant solution, except polarizing filters really don't work like that. A horizontal polarizing filter is just a grid of fine black horizontal lines, light wobbling in the vertical orientation just gets absorbed. A polarizing filter doesn't CONVERT light TO one polarity, it just absorbs everything else. So your glasses would just be opaque, horizontal polarizer absorbs the vertically polarized light the vertical polarizer absorbs the remaining horizontally polarized light, the 45 degree filter wouldn't have much effect.//   

       You'd think so, wouldn't you.
However, what xaviergisz said.
  

       There's (apparently) this wierd quantum effect where intercalating polarised filters does convert the light to a new polarisation.
It's one of the reasons physicists go on about measuring something changing the result.
Loris, Mar 31 2021
  

       //intercalating polarised filters//   

       {Looks around suspiciously for the intercalary twin}   

       Is it possible that "interpolating" is meant?   

       {Looks up Malus' Law}   

       "Light finds a way!" </JeffGoldblum>
pertinax, Mar 31 2021
  

       //Malus' Law or three-polariser experiment.//   

       Well, that's the first time I've had my mind slightly blown in a while. Especially on something optical. I even, occasionally, use polarization in fluorescence microscopy because if a fluorophore rotates before it emits light, it will likely change the polarity, so you get information about the orientation and freedom of movement in individual molecules. Which is nice.
bs0u0155, Apr 01 2021
  

       Loris, that video is 4 years old, and says they filed patents. Has any progress been made towards a working prototype since?
21 Quest, Apr 01 2021
  

       //they filed parents//   

       Brutal: was the care home too expensive?
pertinax, Apr 01 2021
  

       //Brutal: was the care home too expensive?//   

       Like this perhaps? <link> should help get care home costs down that.
Skewed, Apr 01 2021
  

       Whoops! Fixed, thanks!
21 Quest, Apr 01 2021
  

       //Is it possible that "interpolating" is meant?//   

       That's one of the meanings of intercalate, yes.   

       Google pulls this from Oxford Languages:   

       intercalate
verb
past tense: intercalated; past participle: intercalated
1. insert (an intercalary period) in a calendar.
"a system was introduced to intercalate an extra month in the calendar"
2. insert (something) between layers in a crystal lattice, geological formation, or other structure.
"the interlayer spaces of the graphite host lattice are filled with intercalated layers"
  

         

       21 Quest - are you looking at Skewed's video link?
Loris, Apr 01 2021
  

       The only video I see looks like a tourism infomercial for the Japanese island of Kyushu.
21 Quest, Apr 01 2021
  

       Thank you, [Loris]; TIL.
pertinax, Apr 01 2021
  
      
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