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Nashua;51.0;http://forecast.weather.gov/images/wtf/small/ovc.png;2014-10-23 12:29:22
Saturday, August 3, 2013

A one-ton lens isn't easy, or cheap, to display

Fresnel lenses are very cool. They are, basically, glass with concentric circles carved into the surface, which focuses light with less thickness of glass than a normal lens. They don't make a sharp enough image for cameras, but they're good enough for lighthouses, which used them for a century or more until new optics came along.

In Maine, an 1800-pound Fresnel lensthat was used from 1874 to 1994 at Two Light in Cape Elizabeth is going to be displayed at the Maine Maritime Museum in Bath thanks to some last-minute scrambling. It almost ended up in a warehouse, due to the cost of maintenance. Here's the story.

These things are well worth seeing - if you're ever in Bath, check it out.