Free-Form Micro-Optical Arrays: CAD Tools, Quality Control, and Metrology for Lighting Solutions

Artificial lighting solutions have a large impact on our society, and can be found in many applications of everyday life, ranging from office to automotive lighting. To improve the development of lighting solutions, two important characteristics of light are considered in this work: the spatial distribution and the spectrum of light. For changing the spatial distribution, optical components are required to redirect the light emitted from the light source. Especially, free-form micro-optical components are gaining increasing interest in research and industry because they offer many advantages. The second characteristic, the spectrum of light, is of particular interest with respect to its circadian effect on humans, therefore to improve the non-visual effect of lighting solutions.
First, the improvement of lighting solutions with respect to the spatial distribution is investigated. For this, free-form optics is a very promising because the greater degree of freedom in form can overcome limitations, allowing better optical performance of optical devices. In particular, FMOA combine the advantages of free-form optics and array character, enabling large-area replication and miniaturization of devices. However, These innovative optical components present many challenges in design, fabrication, and quality control.
Solutions were developed for FMOA designs as well as for fabricated FMOA prototypes to overcome such challenges:
For the challenges that are faced with the complexity of form of FMOA designs, CAD tools were developed to analyze FMOA designs for manufacturability. Their objective is to detect critical parts at an early stage and thus shorten production cycles. Further CAD tools have been developed to modify CAD designs, making them compatible with manufacturing process steps.
For the challenges of fabricated FMOA prototypes, a new approach has been developed for improved quality control of FMOAs, based on the conversion of experimentally measured surface topography into virtual 3D models using NURBS surface representation. This makes it possible to link the optical functionality to the surface form, since it is far from trivial to obtain this information during experimental characterization. The generated 3D CAD model enables a computational analysis with optical simulation software programs.
Second, the improvement of lighting solutions with respect to the spectrum is investigated. Given the increasing interest in improving lighting solutions for human needs, a theoretical analysis was conducted to investigate the circadian effect of spectral tuning of a multi-channel LED light source. The results explore the improvement of optical solutions from the user perspective and add an additional aspect relevant to lighting applications.