3D Direct Laser Writing of Highly Absorptive Photoresist for Miniature Optical Apertures

Abstract

The importance of 3D direct laser writing as an enabling technology increased rapidly in recent years. Complex micro‐optics and optical devices with various functionalities are now feasible. Different possibilities to increase the optical performance are demonstrated, for example, multi‐lens objectives, a combination of different photoresists, or diffractive optical elements. It is still challenging to create fitting apertures for these micro optics. In this work, a novel and simple way to create 3D‐printed opaque structures with a highly absorptive photoresist is introduced, which can be used to fabricate microscopic apertures increasing the contrast of 3D‐printed micro optics and enabling new optical designs. Both hybrid printing by combining clear and opaque resists, as well as printing transparent optical elements and their surrounding opaque apertures solely from a single black resist by using different printing thicknesses are demonstrated.

Fabrication of Glass‐Ceramic 3D Micro‐Optics by Combining Laser Lithography and Calcination

“…Up till now the selection for highly absorbing polymerizable materials has been practically non existent, with the notable exception of recently demonstrated Prototype IP‐Black (Nanoscribe GmbH Co. KG) photoresist. [ 167 ] Opaque micro elements had to be created via additional and complex steps as highly absorbing ink incorporation into printed structures [ 168 ] or using non‐transparent film coating techniques. [ 169 ] Efficient absorber materials like SiOC‐based ceramics have been proven to posses high absorption in visible and longer wavelength ranges [ 170 ] and could be used for directly printable aperture elements, needed to achieve imaging systems of the highest quality by reducing aberrations, as vignetting and attenuation of background stray light.…”

Additive Manufacturing of SiOC, SiC, and Si3N4 Ceramic 3D Microstructures

“…Recently, there is a growing demand to combine the production of transparent and opaque 3D structures. [ 37 ] Photopolymerization of opaque resins is very difficult or impossible due to light absorption in the UV–vis–NIR region. We have demonstrated that it is possible to produce black structures without process limitations, since the initial resin is transparent to UV–vis, and opaque structures are obtained only after post‐processing.…”

Two‐Photon Polymerization Lithography for Optics and Photonics: Fundamentals, Materials, Technologies, and Applications

“…Other photo-responsive materials can be used for active optics and optical robots, such as precise medical operations. [735,736] Furthermore, optical opaque photoresists can enhance the imaging contrast of lens, [737] while optically clear yet radiopaque photoresists can enhance the contrast under X-ray computed tomography. [738] Regarding the femtosecond laser beam, there has been much progress in the development of focus modulation methods in TPL for plenty of applications.…”