Our Motivation

The development of optical systems is characterised by the trend towards ever smaller products in which a multitude of functions are integrated cost-effectively in a compact installation space. One example of this trend are smartphones.

These small handheld devices do not only have several extremely flat cameras for different situations, a display and a proximity sensor, they sometimes even feature an infrared sensor and illumination system for three-dimensional detection of the surroundings. At the same time, we can expect further individualisation of products in the future, including customised individual solutions.

We respond to the trend of individualised, cost- and resource efficient products by simulating and designing additive manufactured optical elements and systems, which enable completely new and customised solutions.

We are countering this trend with additive manufacturing of optical elements and systems, among other things, which makes completely new and customised solutions possible. Unfortunately, additive manufacturing is often accompanied by a limited quality of the resulting products.

We resolve this conflict of objectives between costs, quality and functionality by mapping the possibilities and limitations of current and future additive and conventional manufacturing processes, some of which are developed within the framework of PhoenixD, in our simulation environment. In this way, we can optimise the optical system and its production in a targeted manner.

In the future, process data will be transmitted back to the simulation environment during production in order to identify deviations. Using this knowledge, the optical system in the manufacturing process will be optimised so that errors are compensated for as far as possible.

Our Research

As task group macro-optical systems, we develop novel approaches and concepts for optical components and systems at the interface between required precision, low costs, high customisation and functional integration.

On the one hand, we are looking at ultra-precise optical components and systems such as space interferometers or, together with the task group Micro- and Nanophotonics, lightweight reflectors based on nanoparticles, which have an efficiency of up to 100 %. On the other hand, within the framework of PhoenixD, we deliberately use imperfect technologies and manufacturing processes for the cost-effective production of highly integrated optical systems.

The example of Raman spectroscopy shows that despite restrictions in the use of additive manufacturing technologies (for example inhomogeneities and gas inclusions in the transparent volume), highly functional systems can be designed through the targeted use of the associated design possibilities (high geometric design freedom). The functions of focusing the laser beam, collecting and focusing the Raman backscattering and a mechanical threading are integrated into one optical component. In this way, a system is created that shows a lower sensitivity than conventional solutions according to current results but offers the potential of broad availability, for example, in medical diagnostics, due to significantly reduced costs and system complexity.

Figure 1: Scattering behaviour of an additively manufactured transparent sample using multijet modelling: The photos show patterns on a screen at a perpendicular incidence of radiation (upper row of photos) and an incidence angle of 45 degrees (lower row of photos). In the photos on the left, the surface roughness due to the manufacturing process is included; on the right, the surface is polished.

We are further shaping these approaches by systematically opening up the solution space for designing future Optomechatronic Systems. In cooperation with the Task Group M2, we characterise additively manufactured components to detect geometric deviations as well as surface and volume effects such as scattering and dispersion anisotropically as a function of manufacturing technology and parameters (Figure 1).

The data obtained will be generalised and implemented in our simulation environments so that the design and optimisation of optical systems is extended to include the boundary conditions of additive manufacturing. In this way, ideal macroscopic optical systems can be designed for any manufacturing technology.

Also, the ideal manufacturing process for fulfilling the requirements can be identified. Simultaneously, we are developing analytical procedures to define starting points for the design and optimisation of optical systems, as shown in Figure 2 using the example of a collimation system for radiation sources that can be modelled as Lambert emitters.

Figure 2: Beam collimation efficiency for uncoated lens systems and Lambertian point light sources as a function of different numbers of lenses and acceptance angle. The refractive index of the material is n=1.46.

The next steps are

to consider post-processing and coating technologies of Task Group M3

implementing novel materials, including the possibility of selectively actuating some of their specific optical properties (Task Groups M1 and S2) and

linking with models describing the human visual sense to simulate light-based communicationsystems, for example, in traffic areas.

In parallel, multi-physical simulations are initially being carried out for selected applications, for example, to describe the influence of temperature and mechanical stress on the optical properties of polymer fibres [Suar20]. In addition, the gap between macroscopic and nanoscopic systems and manufacturing technologies must be bridged on the simulation side by pursuing multi-scale simulation approaches and implementing manufacturing technologies such as two-photon polymerisation in the simulation environment in the manner described.

The next ten years' goal is to establish an open-source software platform for optics simulation with the other Task Groups working on simulation questions. So the research results of the Task Groups are bundled and made accessible to a broad scientific public.