3D printing arrives at micro optics

January 23, 2017 // By Christoph Hammerschmidt
High design flexibility, fast design iterations and prototypes early in the design cycle, these are the promise of 3D printing for many industrial branches. But when it comes to the resolution and precision requirements typical for the optical industry, 3D printing so far has not been a viable option. With a range of 3D printing solutions, Nanoscribe is GmbH (Karlsruhe, Germany) is now addressing the micro optics industry and related R&D institutions.

According to Nanoscribe, a spin-off of Karlsruher Institut für Technologie (KIT), a broad range of almost arbitrary micro-optical shapes including standard refractive micro-optics, freeform optics, diffractive optical elements or even multiplet lens systems can now be printed in a one step-process by means of Nanoscribe's Photonic Professional GT 3D printers, tailored solutions and materials.

The additive manufacturing approach allows to directly fabricate micro-optical components from polymers with optically smooth surfaces, high shape accuracy and significantly smaller geometrical and design constraints than standard fabrication methods.

The workflow associated with additive manufacturing also drastically cuts the design-iteration phase and ideas can be turned into functional prototypes within just a few days.  Nanoscribe claims to close the gap between 3D printing and micro-optics with its GT 3D tool.

The freedom of design provided by 3D printing also implies that almost any concave or convex or entirely freeform surface shape can be fabricated with this technique. Recently, researchers from the University of Stuttgart (Germany) directly 3D printed doublet lens systems onto CMOS image sensors thereby creating a compact high-performance imaging system. Besides achieving a surprisingly high optical performance, the design iteration process was drastically accelerated - it took less than a day to implement new designs from the idea to the final part.

A structure demonstrating the shape accuracy and optically smooth surfaces achievable by using this technology are hemispherical micro lenses (figure 1). They have a shape accuracy better than 1 µm and a surface roughness better than 10 nm Ra. The array with a size of 1 square centimeter in total and semispheres with a height of 150 µm was written into a solid negative tone resist. Due to an optimized combination of hardware and software components it is possible to achieve a high and consistent precision on the whole area of the writing field. Micro-optical components at wafer level can be fabricated by the same technology.

Array of semisphere micro-optics fabricated with a Photonic Professional GT.


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