3D printed complex microoptics: Fundamentals and first benchmark applications

by : Prof Harald Giessen
4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany

Abstract: We introduce 3d printed complex microoptics [1], spanning a range between a few micrometers up to 5 mm. Our lens system consists of aspherical multiplet lenses which can give high numerical apertures with simultaneously excellent imaginag properties over the entire field of view, even directly on an optical fiber tip. Combining several printed materials with different refractive indices and dispersions and the combination with diffractive elements allows for realization of micro-optical achromats or even apochromats which are aplanatic (no first- and third-order aberrations such as spherical aberration, astigmatism, coma, distortion etc.) and achromatic for 3 wavelengths (red, green, blue). We also demonstrate the direct printing of black resists, which results in aperture stops and blackened hulls. Atomic layer deposition yields antireflection coatings on all optical elements. Confocal surface profiling and wavefront interferometry demonstrate accuracies far better than lambda/20. In combination with high-resolution nanostructuring, also 3D holograms and metasurfaces can be included. We utilize these methods to demonstrate the smallest endoscope in the world, being able to pass through a root canal of a tooth, as well as ultracompact sensors with hologon or hypergon lenses or a set of Scheimpflug lenses with nearly 2pi steradian imaging solid angle. Illumination systems as well as holographic projectors and beam shapers directly on optical fiber tips are demonstrated. Coupling single quantum emitters or single photon detectors to single mode fibers is demonstrated. Furthermore, single-fiber optical trapping of polystyrene beads, live cells, or atomic systems becomes a possibility. We also demonstrate the the endurance of such optics is large enough to incorporate them directly into a hybrid fiber/solid state laser (see figure 1) [2].

[1] T. Gissibl, S. Thiele, A. Herkommer and H. Giessen, “Two-photon direct laser writing of ultracompact multi-lens objectives”, Nature Photonics 10, 554 (2016).

[2] S. Angstenberger, P. Ruchka, M. Hentschel, T. Steinle and H. Giessen, “Hybrid fiber-solid-state laser with 3D-printed intracavity lenses”, Opt. Lett. 24, 6549 (2023).