Hybrid optical (freeform) components—functionalization of nonplanar optical surfaces by direct picosecond laser ablation

Abstract

The performance of optical systems is typically improved by increasing the number of conventionally fabricated optical components (spheres, aspheres, and gratings). This approach is automatically connected to a system enlargement, as well as potentially higher assembly and maintenance costs. Hybrid optical freeform components can help to overcome this trade-off. They merge several optical functions within fewer but more complex optical surfaces, e.g., elements comprising shallow refractive/reflective and high-frequency diffractive structures. However, providing the flexibility and precision essential for their realization is one of the major challenges in the field of optical component fabrication. In this article we present tailored integrated machining techniques suitable for rapid prototyping as well as the fabrication of molding tools for low-cost mass replication of hybrid optical freeform components. To produce the different feature sizes with optical surface quality, we successively combine mechanical machining modes (ultraprecision micromilling and fly cutting) with precisely aligned direct picosecond laser ablation in an integrated fabrication approach. The fabrication accuracy and surface quality achieved by our integrated fabrication approach are demonstrated with profilometric measurements and experimental investigations of the optical performance.

Integration of an opto-chemical detector based on group III-nitride nanowire heterostructures

“…To this end additional excitation beam shaping and splitting functionality [13] can be implemented by applying advanced laser ablation of shallow profile portions and high frequency diffractive structures on micro machined surfaces [14].…”

One-step generation of hybrid micro-optics with high-frequency diffractive structures on infrared materials by ultra-precision side milling

“…The major advantage of the proposed UPSM in fabricating hybrid infrared optics is that the primary reflective/refractive surface and the secondary diffractive nanostructures of the hybrid micro-optics can be simultaneously generated, without complicated machining processes. In comparison, for previous methods, multi-step processes that combines ultraprecision machining technologies and non-mechanical methods were normally required to obtain the hybrid IR micro-optics with desired shapes [6,8]. However, this multi-step processes not only introduce unnecessary machining errors, but also is relatively high-cost and low-efficient.…”

“…This difficult-to-machine nature of IR materials can be more significant in the fabrication of hybrid optics with complicated hierarchical micro/nanostructures. Generally, complex machining technologies that combines multi-step machining processes are required to generate hybrid structures on IR materials, which is very low-efficient and difficult to control form accuracy [6][7][8].…”

Theoretical and experimental investigation on the novel end-fly-cutting-servo diamond machining of hierarchical micro-nanostructures

“…The result suggests that the secondary nanostructures of the FFS-NP are of the functions of 3D diffraction gratings, which may be very useful for the correction of optical aberration and special imaginations of optical systems [28,29]. From the viewpoint of optics design, the surface can be regarded as an element comprising refractive/reflective freeform and high-frequency diffractive structures, constructing the hybrid micro-optics for function integration of the optical component [5,30]. (d) Compared with FTS/STS, the EFCS system made the generation of secondary nanostructures free from the dependence on mechatronic system dynamics.…”