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| Joined: | Thu Mar 26th, 2009 |
| Location: | Colorado USA |
| Posts: | 10254 |
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Double domed is definitely the )) with both sides convex at the same radius (or very close to the same radius).
Think of it in terms of a standard window...the fact that the window (flat for example) is the same thickness from center to edge, all light rays that pass through the window bend the same because they are going through the same thickness of glass. The more deviation in thickness you get between the two sides as you go from center to edge of the crystal (such as a flat inner surface and curved outer surface), the more "distortion" you are going to get.
The double domed design lends to act more like a flat window pane in this sense than a magnifying lens.
Sorry if I have beat this to death...truly not my intent...;) ....but I agree with Oscar that it seems like many WIS get thrown by the terminology.