Hannover Messe 2023: KIT presents inkjet-printed optical components

19 Apr 2023

Researchers explain how components can be manufactured energy-efficiently.

In many photonics-based devices and systems, optical filters ensure that light is reflected or transmitted according to specific wavelengths.

Now, researchers at the Karlsruhe Institute of Technology, Germany, (KIT) have developed new materials and a new process technology to produce such filters with the inkjet printer. They are showing the cost-effective and energy-saving manufacturing process this week, through April 21, at Hannover Messe 2023 (Future Hub, Hall 2, Stand B45).

“Optical mirrors and filters are needed wherever light is used,” said Professor Uli Lemmer, head of the Light Technology Institute at KIT. “Until now, however, they have been manufactured in complex vacuum systems that consume a lot of energy and material and have a comparatively low throughput.”

Cutting costs

With their innovative process developed as part of the 3D Matter Made to Order cluster of excellence of KIT and Heidelberg University and as part of a project of the Baden-Württemberg Foundation, Lemmer and his team want to reduce manufacturing costs and adapt the properties of the product flexibly to the respective application adjust.

That is why the researchers are producing the inkjet optical filters (IJPOFs) in the inkjet printer. They employ two different inks specially developed for this process. The first is printed drop by drop until the layer has the desired thickness. The material is then cured using UV light. The next layer is then made from the second ink using the same process.

“One of the challenges here is to determine the printing and drying parameters precisely, but above all to vary the layer thicknesses precisely,” said Lemmer. “Because the layer thickness determines the properties of the filter.”

The process developed at the LTI is suited to custom-made products, which are usually associated with high costs because there have not yet been any efficient production options for them. The researchers see a high demand for the filters from the laser printer, among other things, in spectroscopic processes in medicine, measuring devices for the chemical industry or telescopes with a high degree of reflection that have to cover a large area.

Spin-off planned

The LTI scientists use the innovative inkjet printing process not only to produce optical filters, but also for dielectric mirrors. These high-tech mirrors, also known as Bragg mirrors, are used in camera systems, microscopes or sensor systems, among other things, and direct the light with the right wavelength to exactly where it is needed.

With the new printing process, the KTI researchers can print such mirrors from nanoinks on different surfaces. The filters have an ultra-high reflectivity of 99 percent and tailor-made optical properties. Together with his doctoral students, Lemmer wants to lead the innovative technology for the production of a new generation of optical filters and mirrors to commercial success with a spin-off.