Two-photon direct laser writing of ultracompact multi-lens objectives

Abstract

Current lens systems are restricted in size, shape and dimensions by limitations of manufacturing. Multi-lens elements with non-spherical shapes are required for high optical performance and to correct for aberrations when imaging at wide angles and large fields. Here we present a novel concept in optics that overcomes all of the aforementioned difficulties and opens the new field of 3D printed micro-and nano-optics with complex lens designs. We demonstrate the complete process chain, from optical design, manufacturing by femtosecond two-photon direct laser writing and testing to the application of multi-lens objectives with sizes around 100 µm, and validate their high performance and functionality by quantitative measurements of the modulation transfer function and aberrations. The unprecedented flexibility of our method paves the way towards printed optical miniature instruments such as endoscopes, fibre-imaging systems for cell biology, new illumination systems, miniature optical fibre traps, integrated quantum emitters and detectors, and miniature drones and robots with autonomous vision.A dditive manufacturing enables new and unprecedented engineering and production possibilities that are predicted to have an enormous impact in the twenty-first century. The technology allows for the simple three-dimensional (3D) printing of volumetric objects directly from a computer-aided design 1 . So far, additively manufactured objects are mostly fabricated from metals, ceramics and opaque plastics. There are a number of different fabrication methods to manufacture small and high-performance micro-optical systems 2-10 ; however, these technologies suffer from drawbacks such as limited miniaturization, inability to combine multiple elements, restrictions in designing the surfaces 2-4,11 and problems with the alignment 12 .Multiphoton lithography is one of various 3D printing technologies that realize the fabrication of 3D objects 13-15 . Using femtosecond laser pulses and two-photon absorption, this manufacturing method takes 3D printing down to submicrometre feature sizes and therefore pushes the ongoing trend of miniaturization forwards. Direct laser writing with highly transparent photoresists enables 3D printing to enter the realm of manufacturing optical elements at the micro-and nanometre scale [16][17][18][19][20][21][22] . Thus the precise fabrication of complex optical elements on demand becomes possible.We demonstrate that 3D direct laser writing is a suitable tool for fabricating complex multi-lens optical systems that show high optical performances and tremendous compactness. Until now multi-lens optics that have comparable performances are considerably larger 12,23 and at the same time do not show the manifold compound structures and possibilities presented here. Our optical devices consist of several different free-form lens elements with air in between. This work is right at the interface between microand nano-optics and represents a paradigm shift for micro-optics. It takes only a few hours from lens desig...

Combining in-situ lithography with 3D printed solid immersion lenses for single quantum dot spectroscopy

“…In the present paper we demonstrate the possibility to combine deterministic fabrication technology with micrometric-sized hemispheric SILs (h-SILs). The new approach we present for the deterministic fabrication of QD-based structures with enhanced light extraction is based on the combination of state-of-the-art low-temperature lithography15 with optimized femtosecond 3D laser writing242526. This advanced fabrication procedure is demonstrated here only for QD-based sources, but can in principle be transferred to other solid-state quantum emitters.…”

Hybrid Subtractive-Additive-Welding Microfabrication for Lab-on-Chip (LOC) Applications via Single Amplified Femtosecond Laser Source

“…On the other hand, additive manufacturing realized with ultrafast laser is superb in creating and integrating true 3D structures on a wide array of substrates 32 and structures. 10,[33][34][35] What is more, it allows multimaterial fabrication during formation of single structure thus enabling 4D printing. 9,36 However, as it is based on a point-by-point structuring, it lacks the throughput to fabricate the whole LOC system fast enough to be commercially viable.…”

Fiber-integrated Brillouin microspectroscopy: Towards Brillouin endoscopy

“…An alternative solution could be a complex¯ber lens, fabricated by the direct laser writing method on the tip of a multicore optical¯ber that would enable light focusing in a single aberration-free spot. 27 …”