Re: Fresnel lenses

I started to post this as a response to a comment. It started to get to big and needed it's own entry.

genebreshears pointed out that Fresnel lenses are still being made for various uses. And of course the technological achievements of Augustin Fresnel have no reason to simply fade away. Well, yes, he's right, My mistake. I should have gone on about that a little. Fresnel lenses for lighthouses are no longer produced as the newer electric beacons are cheaper and have a much more powerful light.

Lighthouse Fresnel lenses not only have different sizes, or "orders" but they are also made unique to each lighthouse they are in. Some employ a simple magnified light that beams out in all directions at the same time. Others are a rotating single spot, it's rotation speed creates a flash that is separated by a number of seconds depending on the speed of the rotation. Still others have multiple rotating spots that create the lighthouse flash or "characteristic". Point No Point has a characteristic of three short flashes followed by [I think] a 15 second pause. Add color to a characteristic, like say thered at the West Point lighthouse at Discovery Park and you get an even more complicated lens. Mariners would use the flash to identify the lighthouse they were observing.

The lens at Cape Mears had it's "bulls eye" segments smashed out. It's a first order lens and was "Very Expensive" when it was purchased back in 1890. To restore it they have to research the lens to identify how it's characteristic was created. They also need to research methods for repairing it since they don't make lighthouse lenses anymore. As Gene pointed out, they still make Fresnel lenses, which is probably why they can still attempt to repair the Cape Mears lens at all.

It was going to take a while to repair the lens. The restoration of the lens as well as the upkeep of the lighthouse is all being done by visitor donations.

The restoration may have been completed and Juli and I are going to go back and have a look.