New Material For Fast-Change Sunglasses, Data Storage

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.

Comments

Slow Memory

[im_thatoneguy]

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

[erayd]

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

[Fred_A]

Especially if you need to keep the UV source on to keep the data stored...

Re:Slow Memory

[EdZ]

And you need to keep refreshing RAM too. With a refresh every 30ms, this could be used for medium-term storage in an optical computer.

Re:Slow Memory

[Qzukk]

Probably not, but I bet you could put a few big ones behind an LCD mask.

Re:Slow Memory

[BitZtream]

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.

Something missing?

[OpenSourced]

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?

[Jah-Wren Ryel]

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.

So when I turn out the lights...

[macraig]

... I'm simultaneously deleting my entire terabyte of porn!? Noooooo!

The eye adapts slowly

[oneirophrenos]

It's all good and well, but the eye doesn't adapt to changes in lighting as fast as this material does. What if the lens (and the eye) were subjected to a bright light from the angle of, say, 70 degrees? This wouldn't be blinding, because it would not hit the area of high acuity vision on the retina, but would nevertheless cause the lens to dim. So we would have a situation where the light hitting the retina would be significantly reduced, but the eye would still be adapted to conditions of relative brightness. We would effectively be blind (think of going to dark indoors on a bright sunny day).

Re:The eye adapts slowly

[Al Al Cool J]

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).

Re:The eye adapts slowly

[0123456]

"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 to darken.

Re:The eye adapts slowly

[swillden]

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.

Re:The eye adapts slowly

[blincoln]

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 wavelengths. My camera isn't sensitive to wavelengths shorter than UV-A or I'd test it myself.

Obligatory Douglas Adams reference...

[LordAlced]

But does it turn dark in the presence of danger?

epileptics-need-not-apply. Why not?

[MichaelSmith]

I can imagine situations where the ability to quickly remove a visual stimulus would actually help a person with photosensitive epilepsy.

Re:epileptics-need-not-apply. Why not?

[maroberts]

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.....

Re:epileptics-need-not-apply. Why not?

[value_added]

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.

Re:epileptics-need-not-apply. Why not?

[Trouvist]

Yes, she is.

Re:epileptics-need-not-apply. Why not?

[maroberts]

I don't have a sister. Wait a minute, whose bed is this? There's someone behind me... Damn, my glasses have gone dark, can't see a thing.

Re:epileptics-need-not-apply. Why not?

[failedlogic]

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.

flicker probably not an issue

[boog3r]

(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 likely considering the optimal cycle time produces the highest flicker rate. Any UV transition slower will produce less flickers/sec, while a faster transition will create an increasingly static tint (chemical can't transition quickly enough).

Now sitting under a 60Hz black light, that may be kind of trippy.

Re:flicker probably not an issue

[dunkelfalke]

as you might or might not know, the windshield filters the uv rays. phototropic glasses cannot function in a car.

Re:flicker probably not an issue

[DNS-and-BIND]

Apparently, I have hallucinated the suntan or sunburn that I get on long car trips. Thanks for the info, though!

Re:flicker probably not an issue

[dintlu]

This is not true. Sunburns are caused by UV rays.

http://en.wikipedia.org/wiki/Sunburn#Cause

Re:flicker probably not an issue

[Bigjeff5]

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.

But is the reverse reaction temperature sensitive?

[misterjjones]

The biggest problem with current photochromics in sunglasses is not the speed, but the fact that they darken beautifully in strong sunlight, but only when it's cold.

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.

Blue, non-polarized, non car = whatever

[markdavis]

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 :)

Re:Blue, non-polarized, non car = whatever

[miggyb]

Isn't that exactly how LCDs work? When no charge is applied to a liquid crystal, it lets light through, but when there's an electrical charge, it becomes dark. All you'd really need is a pair of glasses with a battery, photodetector, and two monochromatic LCD cells the size of the actual lens. I don't think it'd be that much of a pain in the ass to have to recharge your glasses at night.

Re:Blue, non-polarized, non car = whatever

[fahrbot-bot]

Yet, there is no way to have changing, polarized lenses (right now).

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 lenses that are polarized and respond to both visible light (less darking) and UV light (more darking). These are also available from Oakley.

Re:But is the reverse reaction temperature sensiti

[tresstatus]

I believe you are totally missing the point for the light sensitive glasses. they are never meant to be sunglasses. they are meant to protect your eyes from UV rays so that you don't damage your eyes. they also only barely darken anything you are looking at, with it being most noticeable on white things, like clouds or sheets of paper. what they really excel at is taking the edge off when you are looking at an object that is extremely bright........ EXCEPT FOR THE SUN. you aren't supposed to stare at the sun while you wear these.

I wear glasses that have the newest version of the transitions lenses. they turn much faster in heat than they do in cold... just the opposite of the older version. even still, when i wear them, i can't tell that they've changed to dark until I take them off and look at them.

my advice is that if you want your prescription glasses to work on the beach, you have 3 options: buy prescription sunglasses, buy a style of sunglasses that comes with a built-in clip-on (usually magnetic), or get contacts and wear regular sunglasses.

Re:Peril-Sensitive Sunglasses

[PixetaledPikachu]

perl-sensitive sunglasses? sweet!

What's new?

[ChrisMaple]

I've used a welder's face shield that changes to dark in the presence of UV from welding faster than I can perceive. It changes back to clear when welding stops. Am I missing something that makes this new?

Re:What's new?

[pereric]

Maybe that it doesn't need external power or control. IIRC, the auto-dim welding helmets I know of need an external power source (small solar panel + battery I presume), and dims by applying a current to the glass. I was also going to ask if this could be used for a simpler welding mask, but 30 ms is perhaps too slow for protecting against the lots of UV arc welding produces.

Re:Peril-Sensitive Sunglasses

[Anonymous Coward]

Those would be useful too, and actually a lot more feasible with current technology. Just add a camera, a microprocessor running OCR, and a perl parser -- and turn the glasses opaque the moment the parser finds legal perl code. This could save millions of young programmers from brain damage. The only problem is to create software that can distinguish between perl code and random OCR errors.

Re:Peril-Sensitive Sunglasses

[1u3hr]

I'd prefer ones that filtered out COBOL or FORTRAN myself.

Re:Only ultraviolet? So they are almost useless

[rockNme2349]

They are activated by ultraviolet light...

Since they turn dark blue, I'll let you figure out what type of light they filter out.

Re:But is the reverse reaction temperature sensiti

[An ominous Cow art]

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

Photosensitive Welding goggles work well

[billstewart]

I've taken a couple of welding courses over at Techshop, 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" technology is just flip-up green lenses.) Unfortunately, the automatic ones cost about $200, as opposed to non-adjustable welding helmets that are usually under $100 or torch-welding goggles that are priced like sunglasses.

If this technology is dark enough for welding, ,and not too expensive it's fast enough to be effective.