Freeform Surfaces Present Opportunities and Challenges
The classic example of a freeform surface in ophthalmic applications is the varifocal lens commonly used in eyeglasses. Due to the normal aging process, the eye’s ability to adapt between near and far slowly decreases. This leads to discomfort, especially at close range. The great advantage of varifocal lenses is that they combine different strengths in one lens. In contrast to single-vision lenses, they allow for a combination of three vision ranges: distance, intermediate, and near vision. Compared with simple rotationally symmetrical lenses, however, the description of these freeform surfaces is very complex and the calculation costly, as they are individually adapted to each spectacle wearer and each eye for optimal results.
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