The technology is surprisingly expensive, still. But the biggest problem is that photochromic glass is guaranteed to last at most two year on eyewear, which on cars would probably mean a few months, and even less if the car is not garaged.
Another problem is that it has a slow reaction time, especially when turning back transparent. This means that if you drive outside during the day and then enter a tunnel, the windows will stay dark.
A better alternative is electrochromatic windows, whose darkness can be controlled at will. These are even more expensive, and so far it appears they only sell commercially for Ferraris - http://www.saint-gobain-sekurit.com/en/index.asp?nav1=PR&nav2=VPD&id=372
Lenses made from polycarbonate, the same type of plastic used for the space shuttle windshield, are about 50 times stronger than other lens materials.
It doesn't, it is made of glass and plastic film to it from coming apart.
No, most of the time you can get the same quality of auto glass from an original equipment manufacturer (OEM). The windshield is made to the same dimensions and specs as where the dealer would get it from. For more info search OEM on Google.
http://en.wikipedia.org/wiki/Photochromic_lenshotochromic lenses are lenses that darken on exposure to UV radiation. Once the UV is removed (for example by walking indoors), the lenses will gradually return to their clear state. Photochromic lenses may be made of either glass or plastic. The glass version of this type of lenses was first developed by Corning in the 1960s. More recently, plastic versions of these lenses have been commercialized. The first of these was the Photolite lens sold in the early 1980s by American Optical Corporation. The first commercially successful plastic photochromic lens was introduced by Transitions Optical in 1991.[1] The glass version of these lenses achieve their photochromic properties through the embedding of microcrystalline silver halides (usually silver chloride), or molecules in a glass substrate. Plastic photochromic lenses rely on organic photochromic molecules (for example oxazines and naphthopyrans) to achieve the reversible darkening effect. The reason these lenses darken in sunlight but not indoors under artificial light, is that room light does not contain the UV (short wavelength light) found in sunlight. Automobile windows also block UV so these lenses would darken less in a car. Lenses that darken in response to visible (rather than UV) light would avoid these issues, but they are not feasible for most applications. In order to respond to visible light, it is necessary to absorb it, thus the glass could not be made to be clear in its low-light state.
It depends on how large the crack is. If the crack is bigger than the area of a quarter, the windshield needs to be replaced. The repair or the replacement can be made at almost any auto-body shop, it seems.
The best glue for this is made by 'Loctite' and is called Auto mirror adhesive. Sold at many auto parts stores
Hard contact lenses are made of a plastic polymer called polymethyl methacrylate.
Aurolab lenses are made of high-quality acrylic material. These IOLs are used in cataract surgeries.
The Canon T70 camera uses Canon FD lenses. These are manual-focus lenses, but have auto exposure when used with the T70. Most FD lenses made by Canon are very high quality. They can almost always be found at modest prices through a well-known internet personal marketplace website.
It was made of stuff.
Vehicular windshields are made of laminated auto glass. There is a polymer layer between the glass sheets that provides a "flexible strength" to the glass to keep it from breaking into large, sharp pieces. The advantages of this type of glass in a windshield are pretty obvious. Links can be found below to check facts and learn more.
The raw material of lenses is plastic polymer in most cases. There are some lenses which are made from glass materials as well.