A lens is a specially shaped pieces of glass or transparent plastic, that is used to focus light. A convex lens is made from a transparent material that bulges outwards in the middle on both sides.

In a ray diagram, a concave lens is drawn as a vertical line with inward facing arrows to indicate the shape of the lens.

Using 3D-printed fused silica templates, we show that concave as well as convex lens structures can be obtained at high precision by remelting the glass without trading-off on material quality.

To test the new method, the researchers first created a simple plano-convex lens and showed that it had an imaging resolution comparable to a commercial glass lens with the same physical dimensions.