New Material For Fast-Change Sunglasses, Data Storage 133
sciencehabit writes "'Researchers have developed a material that almost instantaneously (30 ms) changes from clear to dark blue when exposed to ultraviolet light, and it just as quickly reverts to clear when the light is turned off. The new material, one of a class called photochromics, could be useful in optical data storage as well as in super-fancy sunglasses.'" A comment to the article notes some of the potential dangers of quick-change sunglasses.
Slow Memory (Score:5, Insightful)
30ms is pretty slow by memory standards.
Could you imagine a CD burner which takes 30ms per bit?
It'll need to get a LOT faster to be used in any kind of processing or storage medium.
Re:Slow Memory (Score:5, Insightful)
30ms is pretty slow by memory standards.
Could you imagine a CD burner which takes 30ms per bit?
It'll need to get a LOT faster to be used in any kind of processing or storage medium.
Who says you have to write things serially? Admittedly write latency would suck, but you can still get a phenomenal throughput if you write a whole bunch of bits in parallel.
Re:Slow Memory (Score:4, Informative)
Which is exactly what todays 48x burners and hard drives already do.
I wish people would realize that hardly anything in a modern computer is done serially anymore. Flash drives, standard hard drives, CD/DVD drives, all of them read/write multiple blocks at once to improve throughput without actually doing anything physically faster.
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Really less and less things are happening in parallel in modern computers, because as speeds increase it becomes more difficult to synchronize all the signals -- take a look at PCIe, SATA, SAS, etc.
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Why is it unfeasible to write that many bits at once? As far as I can see there's no practical reason that would prevent a write system with far more than that many simultaneous channels - and more channels equals more throughput.
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You can fit that many UV diodes in a single drive enclosure?
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Probably not, but I bet you could put a few big ones behind an LCD mask.
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What about scanning the UV laser. I can't imagine that the material needs 30ms of constant high intensity UV light to change.
It may take 30ms to react to the light, but not require 30ms exposure.
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Especially if you need to keep the UV source on to keep the data stored...
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Could you imagine a CD burner which takes 30ms per bit?
No, no I couldn't. Could you help visualize it for me?
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Could you imagine a CD burner which takes 30ms per bit?
Could you imagine a CD burner that takes 30ms per CD?
Something missing? (Score:5, Insightful)
Nowhere in the article they mention how the data is going to be 'stored'. If you need to be constantly bathing the material with UV light just to keep it dark, there is not much storage going on, IMO. Of course there might be missing data from the article, but they should explain a bit more.
Re:Something missing? (Score:5, Funny)
Of course there might be missing data from the article, but they should explain a bit more.
That part was written in photochromic ink, you need to get a copy of the original publication and expose it to UV light in order to find out those details.
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If you need to be constantly bathing the material with UV light just to keep it dark, there is not much storage going on, IMO.
That's why you have to make sunglasses out of the stuff.
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I'm not calling the concept feasible, mind you, but do remember that our dynamic memory is currently based on removing and re-applying an electric charge to billions of capacitors hundreds of times per second. DRAM, according to Wikipedia, is guaranteed to hold its state for 64ms. If this one has 30ms, it's not that bad.
(Or wouldn't be if it could *write* as fast as DRAM does. Of course t
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Nowhere in the article they mention how the data is going to be 'stored'. If you need to be constantly bathing the material with UV light just to keep it dark, there is not much storage going on, IMO. Of course there might be missing data from the article, but they should explain a bit more.
You need to constantly power your RAM in order to keep it storing information. All it means is that this could be useful for volatile storage.
One more step towards peril-proof sunglasses (Score:1)
no text
So when I turn out the lights... (Score:5, Funny)
... I'm simultaneously deleting my entire terabyte of porn!? Noooooo!
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Hey - keep the UV lamp on. Get off _and_ get tan. Just try not to burn the bits.
The eye adapts slowly (Score:4, Insightful)
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Perhaps. But it seems to me that the experience of these things going dark would be very similar to the common everyday experience of simply putting on a pair of sunglasses, something I've done in just about every lighting condition, and usually while driving. The only time I can recall it ever being a problem is when I've done it at night (cue Corey Hart).
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... usually while driving.
That's the problem with this and every other UV adaptive lens treatment: Glass (like, for example, your windscreen) blocks UV.
So, they don't actually work when you're driving.
This is why I always get frames with clip on sunglasses with my glasses. Although, since I always end up losing the sunglasses part within a year, I'm considering just lashing out and getting prescription sunglasses.
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"Glass (like, for example, your windscreen) blocks UV. So, they don't actually work when you're driving."
Except in my experience that's not really true.
I had this discussion with my optician last time I got a new pair of driving glasses, and they do darken while driving despite the fact that the windshield should block the UV (though, admittedly, not as dark as they used to go when I drove a convertible).
I can only guess that the windshield doesn't block the full range of frequencies that cause the glasses
Re:The eye adapts slowly (Score:4, Funny)
Although, since I always end up losing the sunglasses part within a year, I'm considering just lashing out and getting prescription sunglasses.
Been there, done that. I lost the prescription sunglasses. Three times. I decided that I just have to squint.
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That's the problem with this and every other UV adaptive lens treatment: Glass (like, for example, your windscreen) blocks UV.
So, they don't actually work when you're driving.
Glass doesn't fully block UV. I take UV photos using regular glass lenses with a UV-A bandpass filter in front. I lose something like 3-4 stops of light sensitivity compared to visible, but at least some of that is probably due to the camera sensor not being designed with UV in mind.
Apparently glass does block UV-B, UV-C, and shorter w
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Safety goggles? (Score:2)
Photosensitive Welding goggles work well (Score:3, Interesting)
I've taken a couple of welding courses over at Techshop [techshop.ws], and there's a range of welding goggle technology out there. Electric-arc welding (MIG, TIG, old-style stick, etc.) needs really dark goggles, and photo-sensitive welding goggles are available and really cool. They're adjustable-strength, and I think the technology is LCDs driven by a photocell, as opposed to a purely chemical mechanism like sunglasses. (For gas torch welding, the glasses don't need to be as strong, and the standard "adjustable" tec
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And that can be fixed with a simple surface layer filter than blocks light from off angles outside a given range.
This really isn't rocket science, nor is this sort of solution anything new.
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What if the eye (without the lens) were subjected to a bright light from the angle of, say, 0 degrees? This would be blinding, because it would hit the area of high acuity vision on the retina, with no lens to dim. So we would have a situation where the light hitting the retina would not be significantly reduced, but the eye would still be adapted to conditions of relative darkness. We would be effectively blind (think of going outdoors on a bright sunny day).
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Obligatory Douglas Adams reference... (Score:5, Funny)
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But does it turn dark in the presence of danger?
Yes. The lenses will leap out of a moving vehicle just prior to impact, while the driver cries "It works, it works!". Eventually, he will wake up in the hospital believing that he's really Leon Trotsky.
radiochromics ? (Score:2)
Does anyone know if a material exist with similar reaction to radio waves and what such a material is called?
Materials called radiochromics normally react
to radioactive radiation not radio waves.
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epileptics-need-not-apply. Why not? (Score:5, Interesting)
Re:epileptics-need-not-apply. Why not? (Score:5, Funny)
Re:epileptics-need-not-apply. Why not? (Score:5, Funny)
Not to mention waking up in the morning and turning round to face the hideously ugly person you picked up at the bar the previous night.....
Your sister isn't that ugly.
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that's my brother
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You just have to learn to sleep with your beer-googles on.
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People should realize that not everyone who is epileptic is photosensitive. Many people seem to have the incorrect impression that flashing lights and such will trigger off a seizure with anyone that has epilepsy. This is a myth.
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This is a myth.
More of a meme I think, at least in the context we are seeing it here. I developed a seizure disorder when I was at college. A friend started to act like I had AIDS. Making a big deal out of something which was for me simple and easy to keep under control.
Another friend of mine has some degree of photo-sensitivity. The biggest problem she described to me was the intense flashing sunlight caused by driving past trees with a low sun angle. One moment the sun is right on your face, then it is dark again. Gla
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Peril sensitive?
flicker probably not an issue (Score:2, Informative)
(not sure why i posted this on their website. i blame the booze).
Did a bit of math and figured out that at 60mph you would need a complete obstruction every 2.5 feet to induce a state change (on-off), 5 feet for a full flicker (on-off-on).
This compound cycles on-off 33.333 (repeating, of course) times/sec. Halve that for a full on-off-on cycle. The human eye can do fine with a video frame rate of 30/sec, but can detect up to 72 frames/sec.
It is possible the flicker may induce optical illusions, but not like
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FTA- "And the compound is so stable that the reactions can be repeated thousands of times."
Without doing the math(s), driving along a tree-lined road ought to kill 'em in a few hundred metres.
Re:flicker probably not an issue (Score:5, Interesting)
as you might or might not know, the windshield filters the uv rays. phototropic glasses cannot function in a car.
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did not know that.
also, i never said anything about a car :)
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Convertible?
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Nobody said anything about four wheels.
Re:flicker probably not an issue (Score:4, Insightful)
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Apparently, I have hallucinated the suntan or sunburn that I get on long car trips. Thanks for the info, though!
Commonly known as a trucker's tan.
On your next trip, I'd suggest wearing a wife beater [wikipedia.org], and maybe some shorts with black socks. I'll guarantee your new tan lines will confuse rednecks, truckers and your fellow nerds. Freaking out the wife and kids is a bonus.
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Well, glas doesn't filter UV completely, but almost. That is the reason for using special quartz glas for UV optics and applications.
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Re:flicker probably not an issue (Score:4, Informative)
This is not true. Sunburns are caused by UV rays.
http://en.wikipedia.org/wiki/Sunburn#Cause [wikipedia.org]
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I've got a fun experiment we can try to test your hypothesis. We take you and stick you in a tanning booth for, oh, say six hours, and see if you get a really awesome tan (your hypothesis) or you come out crispy fried (my hypothesis).
Ready?
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My solution was to drive with my head hanging out the window. You have to keep your mouth shut because of the bugs-of-teeth issue, so conversation with passengers is near on impossible.
Seriously, I couldn't live without them these days. If the time from dark to light was reduced it would be fantastic.
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yes, photochromic is the english word for it, sorry, i used the german term for it by mistake.
Re:flicker probably not an issue (Score:4, Informative)
It filters UV-B and UV-C pretty well, but not UV-A. Phototropic glasses are usually less effective in a car, but not completely useless.
Depending on the wavelength it changes at, these sunglasses could either work great or piss poor. Should be interesting.
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It filters some, not all. Ever notice you can still get a sunburn in a car, it just takes longer.
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Sure they do. I used to have a pair, of the slow change ones, of course. Whenever I left them on the dashboard they'd be good and dark when I put them on. Also hot.
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I'm going to regret it but where the hell did you get the up to 72fps number and if that's true why can almost anyone see the difference between a 75hz refresh rate and an 85hz refresh rate on a CRT.
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But is the reverse reaction temperature sensitive? (Score:3, Interesting)
In hot conditions the temperature sensitive dark=>light process is favoured over the uv sensitive light=>dark process and they stay clear. I don't want glasses that change colour quickly, I want glasses that change stay dark on the beach.
The only use I have for my current "light sensitive" glasses is if I ever go to the Arctic in summer.
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Re:But is the reverse reaction temperature sensiti (Score:4, Informative)
I've been wearing glasses with photogrey lenses since I was about 8, so 35 years or so. I've never noticed a problem with them failing to darken in hot weather.
Larry
If only it would turn completely dark (Score:1)
Peril-Sensitive Sunglasses (Score:1, Funny)
So with a little work, we can finally have the Peril-sensitive sunglasses of Zaphod's fame.
Sign me up for a set.
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Re:Peril-Sensitive Sunglasses (Score:5, Funny)
useless for sunglasses (Score:1)
Blue, non-polarized, non car = whatever (Score:4, Insightful)
Although it sounds interesting, I doubt most people are going to want to look at the world through blue-colored glasses. What would be far more useful would be glasses that the *user* can decide when they turn dark and by how much. 80% of the time I wear sunglasses is in the car, and Transitions and other UV activated glasses are useless for that purpose because they won't change dark.
I also find that polarized sunglasses are *far* more valuable than just plain darkening glasses. Yet, there is no way to have changing, polarized lenses (right now). So.... give me glasses that can change from 100% clear to full polarized (50% dark at least), on-demand, instantly, and I will then get very excited :)
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Unfortunately, if your light source is unpolarized to start, then
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It probably wouldn't be that big a pain in the ass, but most people want sunglasses that they think look good, not sunglasses that can be switched between clear and dark on demand, so it better not cost a lot extra (lots of sunglasses charge for the logo, so those would be easy to compete with on price, but you would be doing so at the cost of quite a bit of margin).
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Although this won't help inside a car (as the windshield blocks UV), Transitions lenses can be polarized. As an alternative, they also offer Drivewear [drivewearlens.com] lenses that are polarized and respond to both visible light (less darking) and UV light (more darking). These are also available from Oakley [oakley.com].
What's new? (Score:5, Interesting)
Re:What's new? (Score:4, Informative)
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Not positive but I assume the "solar cell" is to detect the light from the arc, might not be that difficult to substitude a much smaller photo-electric cell and a hearing aid batter for the much larger versions used in welding helmets. Welding helmets are personal proctective gear where failure can lead to significant injury so they are over-engineered for saftey.
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Yikes...it doesn't go dark until it detects the UV from the welding arc? That would mean there's a short period of time where your eyes are getting a nice blast of UV. Anybody know how short it is?
I think I'll just stick with the manual flip-down glass, thanks.
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Why so dismissive? What if the amount of UV is comparable to flying across the USA five times a year? Maybe it's even less. Dismissing it when you don't have enough information makes you look irrational and reactionary. Or maybe the flippant last line was just a weak joke.
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I'm not one to trust a safety device without knowing how it does its job better than what it's supposed to replace. If that makes me look irrational and reactionary, then I'll just be an irrational and reactionary luddite with a flip-down welding visor.
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That would mean there's a short period of time where your eyes are getting a nice blast of UV. Anybody know how short it is?
A classic "when did you stop beating your wife" class of question.
The glass doesn't transmit UV at all, at any time. The only common substance that is clear and transmits UV is Quartz (or fused silica which is more or less the same substance). Because it requires a much higher temperature to work than plain ole glass, its not used much, other than in UV spectrophotometers, UV sterilization lamps, eprom eraser bulbs, etc.
However, I would not be surprised to if the Chinese "accidentally" sent us a batch of
Only ultraviolet? So they are almost useless (Score:2)
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They are activated by ultraviolet light...
Since they turn dark blue, I'll let you figure out what type of light they filter out.
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UV filtering glass filters some, not all of the UV. Take a nice long car trip with the sun shining on you through those UV filtered windows, you'll still get tanned or burned given enough time.
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Thinking Too Small (Score:1)
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Mikko Alatalo of course