From Spheric to Aspheric Solid Polymer Lenses: A Review
Figure 12
Micrograph of a multiring microlens and thickness measurements; relationship between size, NA value, and focal length (a) before heat treatment; (b) after first heat treatment; (c) after second heat treatment; (d) after third heat treatment; (e) relationship between multiring Teflon pattern size and NA value; (f) relationship between multiring Teflon pattern size and focal length.
