We demonstrate the fabrication of optical elements on the millimeter scale by stitching-free 3D printing via two-photon polymerization, using a commercial microfabrication system (Nanoscribe GmbH). Previous limitations are overcome by the use of a large writing field objective as well as a novel high transparency resist. The printed optical components are free of stitching defects due to a single step exposure and exhibit an unpreceded glass-like appearance due to the low absorption of the resist material throughout the entire visible wavelength range. We print aspherical focusing lenses, characterize and optimize their shape fidelity, and find their optical performance close to the simulated optimum. For comparison with commercially available glass lenses we also fabricate spherical half-ball lenses of different sizes. The imaging quality of the lenses is very similar, underpinning the powerfulness of our fabrication strategy.

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Modern optical measurement technologies such as structured light microscopy or fringe-projection profilometry rely fundamentally on structured illumination of the specimen or probe. Miniaturizing the applied illumination concept enables the availability of these methodologies even in spatial domains that have remained inaccessible so far. Here we introduce a design methodology to realize complex illumination patterns with high diffraction efficiencies in a strongly miniaturized and functional integrated approach. This is achieved by combining the advantages of refractive freeform wavefront tailoring and diffractive beam shaping. This novel concept overcomes classical stray light issues known from conventional diffractive beam shaping and remains valid for micro-optical systems, i.e., beyond the geometric optical regime. Moreover, the design process is in particular optimized to reduce the aspect ratio of the obtained surface features. This strongly improves the manufacturability and as-built performance of the designed optical element, and the feasibility of the approach is demonstrated by the design and realization of monolithic beam shaping units on the tips of optical fibers via two-photon direct laser writing. This provides the means to realize complex illumination patterns in an integrated and mechanically flexible approach.

Simultaneous realization of ultra-large field of view (FOV), large lateral image size, and a small form factor is one of the challenges in imaging lens design and fabrication. All combined this yields an extensive flow of information while conserving ease of integration where space is limited. Here, we present concepts, correction methods and realizations towards freeform multi-aperture wide-angle cameras fabricated by femtosecond direct laser writing (fsDLW). The 3D printing process gives us the design freedom to create 180° × 360° cameras with a flat form factor in the micrometer range by splitting the FOV into several apertures. Highly tilted and decentered non-rotational lens shapes as well as catadioptric elements are used in the optical design to map the FOV onto a flat surface in a Scheimpflug manner. We present methods to measure and correct freeform surfaces with up to 180° surface normals by confocal measurements, and iterative fabrication via fsDLW. Finally, approaches for digital distortion correction and image stitching are demonstrated and two realizations of freeform multi-aperture wide-angle cameras are presented.