Tailored micro-optical freeform holograms for integrated complex beam shaping

Abstract

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.

Fiber-based 3D nano-printed holography with individually phase-engineered remote points

“…Within this context, 3D nano-printing is an outstanding method being particularly suitable for structuring fiber end-surfaces. Due to the flexibility of this method, a variety of functionalities can be incorporated into fibers, examples of which include sophisticated refractive 32 and diffractive 33 lenses and micro-optical components 34 , 35 , with first attempts for the realization of advanced CGHs that solely modulate the intensity being recently demonstrated 36 . Overall, the combination of fibers and nano-printed holograms represents a very promising approach, especially from the application side.…”

Cryptographic Strain‐Dependent Light Pattern Generators

“…[20][21][22] In the field of optics and optoelectronics, additive manufacturing has been already employed to produce aspheric lenses, micro-optics, waveguides, photonic crystals, light-emitting diodes (LEDs), detectors and sensors. [19,23,24] Though 3D printing of macroscopic objects with optical quality and submicrometric resolution is still challenging, [25] a number of approaches have been proposed for improving the achievable accuracy, as well as the rate of printing and the size of the printed objects [26][27][28] Importantly, some applications might exploit light patterns generated from surfaces with lower quality, taking advantage of the design flexibility and customization offered by 3D printing technologies. A relevant example is given by cryptographic labels, [29,30] where the capability to recognize the generated light patterns by naked eye or by a low-cost scanner, without the need of bulky optics and complex optical systems, is highly desirable.…”

3D-printed miniature spectrometer for the visible range with a 100 × 100 μm² footprint

“…A similar development has occurred with diffractive optics, which have evolved from simple gratings 6 to stacked diffractive microlens systems 7 . Along with imaging optics, photonic crystals 8 , waveguides 9,10 , and collimators 11 , complex beam shapers [12][13][14] have been demonstrated. This rapid development reflects the significant potential of 3D printing technology in micro-optics.…”