Sir
And there was me thinking US special ops put their sunglasses _on_ before entering a building with a view to destroying everything inside.
Still, these do sound pretty cool, where do I sign up?
The latest gizmo to be adopted by top-secret special forces troops fighting the Wars on Stuff is liquid crystal ballistic sunglasses which can change colour automatically much faster than traditional "photochromic" offerings - or at the touch of a button. The US Office of Naval Research says it designed the new Fast-Tint …
It is not the speed at which the coating darkens (it is nearly instant for some) it is the speed at which it after that returns to transparent. A welding mask must go dark straight away. If it takes it 60s to become fully transparent again - who cares?
For example - you cannot use glasses with a reactolite coating for driving or at least you should not. It is simply too slow lightening up. Moving from blazing Mediteranean sunshine into a tunnel while wearing reactolite is quite fun, especially if the tunnel is not straight. 5-10s driving of half blind are more than to kiss a wall or a pillar at 80mph.
0.5s to lighten up however is a very respectable change time. Definitely enough for driving. I would not mind specs like this once they become available for Joe Average Consumer.
Reactolite coatings aren't fast enough.
LCD masks have been in common use for years. The first one I found on Google was http://www.ashleysdirect.co.uk/solar-powered-lcd-welding-helmet-ce-approved.html - 37 quid. A bit of shopping around will probably find something cheaper - I just wanted a URL to show that these are commonplace items...
It speaks volumes that it's taken so long to get popular consumer technology into Special Forces kit.
Vic.
@Anton,
Unless there's been some big changes in the last few years the tech of the automatic welding mask is a solar powered LCD.
They instantly darken when the arc is struck, and (almost) instantly lighten when the arc is removed. I suspect the (very short) delay in lightening may be artifical to prevent getting a visual zap when the arc fluctuates during the welding process.
No special coatings, no 60 second lighten up times. See http://www.ashleysdirect.co.uk/solar-powered-lcd-welding-helmet-ce-approved.html for a typical example.
Actually I have done some welding once upon a time. Just not with an automatic mask.
Such exotic items were not available 20 years ago in the Wild East :) In those days the masks there were all with an "always-on" simple tinted glass.
Thanks for enlightening me anyway. We live to learn.
That however does not change what I said regarding glasses. I have yet to see a set of bog standard specs that are LCD changed being sold in my local D&A. If there were I would have bought some :)
Providing they don't negatively affect the thickness of the lense, they'd definitely be on my buy list.
With my prescription, the reactolite style lenses are way too thick and heavy to be comfortable or stylish (about 3 times thicker and heavier than the lenses I normally get). Something about the reactolite lenses that limits the refractive index of the lens material that can be used.
Kind of like sticking your head in the sand? I'm guessing you meant translucent...
I'd be more impressed with a faster reaction time; 0.5 seconds is much slower than the blink reflex, so they'll still be dazzled fast changes in brightness. No good having the glasses tinting *after* being exposed to bright light; It'll be even more difficult to see.
> I'm guessing you meant translucent...
No, he meant opaque.
The trick[1] is to read the paragraph following that one; it mentions the Joo Janta 200 Super-Chromatic Peril Sensitive Sunglasses. Googling for that might mean you understand what everyone else is talking about.
Vic.
[1] ...aside from banging the rocks together, that is...
He came up with the idea of Peril sensitive sunglasses.
"Joo Janta 200 Super-Chromatic Peril Sensitive Sunglasses have been specially designed to help people develop a relaxed attitude to danger. At the first hint of trouble, they turn totally black and thus prevent you from seeing anything that might alarm you."
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"Transition time is less than 0.5 seconds,"
That's far too slow to protect your eyes from a nuclear blast.
Harold Edgerton had the technology for that back in the 1940's, he used it to make a very fast shutter (<1µS) for a camera to photograph nuclear tests milliseconds after detonation.
Awesome pictures, e.g. http://simplethinking.com/home/rapatronic_2.shtml