Fluidic Shaping of Optical Components*

Current methods for fabricating lenses or mirrors rely on mechanical processing - such as grinding, machining, and polishing. The complexity of these fabrication processes prohibits rapid prototyping of optical components, and puts a very high price tag on large lenses and on complex optical elements (known as freeform optics).

We present a simple method, based on free-energy minimization of liquid volumes, which allows to quickly shape curable liquids into a wide range of optical components, without the need for any mechanical processing.

The method is performed by injecting a curable liquid into a bounding frame submerged within an immiscible immersion liquid with equal (or nearly equal) density at which surface tension dominates. After the desired shape is obtained, the liquid can be cured to produce a solid object with nanometric surface quality.

We provide a complete theoretical framework for the minimum energy state of the interface of the liquids, resulting from the balance between hydrostatic, gravitational, and surface tension forces, and subjected to geometrical constraints. We describe the wide range of freeform surfaces that can be produced, and demonstrate the rapid fabrication of such elements, as well as measurements of the components’ shape and surface roughness.