Recently, researchers have demonstrated 3D printing of micron-scale optics with unprecedented performance and reproducibility. In The Optical Society’s journal for high impact research, Optica, researchers report direct fabrication of optical elements just slightly thicker than the diameter of a human hair. They used a technique known as femtosecond laser writing to accomplish this difficult feat and showed that the performance of the optical elements closely matched simulations.
Femtosecond laser writing uses a laser that emits very short pulses of light to selectively harden a light-sensitive material. The material hardens only in the small 3D area where the laser light is focused, and any unhardened material can then be washed away, revealing the 3D structure that has been created.
These home-made systems are sensitive to environmental conditions and variances in laser power and thus can’t reliably create high quality micro-optics. To overcome these problems, the researchers used a commercially available two-photon 3D laser lithography system designed to write nanometer-sized structures. The system, made by Nanoscribe GmbH, is engineered for stability, reliability and quality.
The researchers used the 3D laser writing system to create optical elements known as phase masks. The direct laser writing approach can be used to create optical elements in numerous ways. The researchers found that creating phase masks ring-by-ring beginning at the center or layer-by-layer starting from the bottom, both produced high quality structures.