For polymer 3D printing technologies, there exists a gap between large build volumes, low resolution and small build volumes, high resolution. On the one hand side, classical stereolithographic techniques can be used to build volumes in the range of several cm³ and an accuracy of 10 μm, on the other hand it is possible to cure structures with the size of several nanometers with two-photon polymerization.
Combining both advantages – large building volume and high resolution – in one printing technology would offer a huge variety of applications e.g. printing optical components and adding a functionalization of the surface by a 3D printed micro structure in the same process.
In this presentation, we demonstrate curing of subpixel structures with a standard DLP-projector with an imaged pixel size of around 40 μm. To use this in a printing process, the behavior of the resins under UV radiation must be known and predictable because different parameters are needed depending on the size and shape of the cured area.
Therefore, a parameter study was done to evaluate the dependency of the cured thickness on the shape, the area and the energy of the irradiated pattern. These parameters were used to simulate the cured thickness for a certain irradiance pattern applied by the projector. Based on these simulations a subpixeling technique was applied in order to cure small structures and test simple applications.
The development of additive manufacturing methods has enlarged rapidly in recent years. Thereby the work mainly focuses on the realization of mechanical components. But the additive manufacturing technology offers a high potential in the field of optics as well. Due to new design possibilities, completely new solutions are possible. Thus elements with virtually any geometry can be realized, which is often difficult with conventional fabrication methods.
Depending on the material and thus the manufacturing method used, either transparent optics or reflective optics can be developed with the aid of additive manufacturing. Ultimately, the application or the specification decides on the approach. For example, transmissive 3D printed parts exhibit the disadvantage of a significant reduced transmission. Conversely, reflective 3d printed optics often require a greater amount of rework in order to achieve a sufficient optical quality of the surface. Nonetheless there is a high potential in additively manufactured optical components.
Here, we compare metal optics (manufactured using a selective laser melting machine) with polymer optics (realized either by stereolithography or by multijet modling). In addition to the basic properties, the post-processing of the 3D printed optics is discussed. This includes, for example, cleaning and polishing of the surface using lasers or a robot based fluidjet process for metallic optics. In the case of the polymer optics a dip-coating process was developed in order to improve the surface quality.
Our aim is to integrate the additive manufactured optics into optical systems. Therefore we will present different examples in order to point out new possibilities and new solutions enabled by 3D printing of the parts. In this context, the development of 3D printed reflective and transmissive adaptive optics will be discussed as well.
Finally we will give an insight into our current developments. On the one hand the development of a robot based additive manufacturing platform will be discussed. The aim of this platform is to realize optimized 3D printed optical components, which is not possible with standard additive manufacturing machines. On the other hand, the functionalization of 3D printed optics will be discussed. Thereby functionalization can take place on the surface or in the volume of the 3D printed part. Based on the stereolithography method, a monolithic optical component was 3D-printed, showing light emission at different defined wavelengths due to UV excited quantum dots inside the 3D-printed optics.
In recent years, additive manufacturing methods became more and more prominent. Thereby, these techniques are mainly used in order to realize mechanical components. But the additive manufacturing technology offers a high potential in the field of optics as well. Owing to new design possibilities, completely new solutions are possible. We report on the realization of complex freeform optics using standard 3D printers. We briefly point out the characteristics of 3D printing and its influence on the optical properties. Additionally we address the needed rework of 3D printed optical components. Therefore we apply two different methods - a robot-based fluid jet polishing and a coating method. The advantage of a 3D printed optic lies in its shape complexity. Thus different complex shaped optical elements are discussed. They are used for either metrology tasks or illumination tasks.