3D-inkjet-printing is just beginning to take off in the optical field. Advantages of this technique include its fast and cost-efficient fabrication without tooling costs. However, there are still obstacles preventing 3D inkjet-printing from a broad usage in optics, e.g., insufficient form fidelity. In this article, we present the formulation of a digital twin by the enhancement of an optical model by integrating geometrical measurement data. This approach strengthens the high-precision 3D printing process to fulfil optical precision requirements. A process flow between the design of freeform components, fabrication by inkjet printing, the geometrical measurement of the fabricated optical surface, and the feedback of the measurement data into the simulation model was developed, and its interfaces were defined. The evaluation of the measurements allowed for the adaptation of the printing process to compensate for process errors and tolerances. Furthermore, the performance of the manufactured component was simulated and compared with the nominal performance, and the enhanced model could be used for sensitivity analysis. The method was applied to a highly complex helical surface that allowed for the adjustment of the optical power by rotation. We show that sensitivity analysis could be used to define acceptable tolerance budgets of the process.

Microinjection molding is a mass production method to fabricate affordable optical components. However, the intense nature of this process often results in part deformation and uneven refractive index distribution. These two factors limit the precision of replicated optics. In order to understand the influences of injection molding on freeform optical devices, in this study, finite element method (FEM) was employed to investigate the miniature microinjection-molded Alvarez lenses. In addition, an innovative metrology setup was proposed to evaluate the optical wavefront patterns in the molded lenses using an interferometer-based wavefront measurement system. This measurement setup utilized an optical matching liquid to reduce or eliminate the lenses’ surface power such that the wavefront pattern with large deviation from the freeform lenses can be measured by a regular wavefront setup. The FEM simulation results were also used to explain the differences between the nominal and experimentally measured wavefront patterns of the microinjection-molded Alvarez lenses. In summary, the proposed method combining simulation and wavefront measurements is shown to be an effective approach for studying injection molding of freeform optics.

Aerosol jet printing is an alternative to inkjet printing, the currently most established fabrication technique for printed electronics, with the benefits of small feature sizes, more homogeneous thickness of the printed layers, and the possibility to print on 3D structures. Printers are available on the market, in which the aerosol is generated outside of the print heads, with the disadvantage that only continuous operation is possible due to the long distance between atomization unit and print head. We report on the development and validation of a new integrated principle, with the atomization of the ink directly inside the print head. This enables a compact design, printing in all spatial directions and jet-on-demand operation. Based on fluid dynamic simulations, an optimized integrated print head design was developed, and fabricated. First tests have been performed in a preliminary laboratory test setup. The successful focusing of the aerosol to approximately 1/7 of the spread of the non-focused aerosol spray was validated in experiments, thus confirming the operating principle of the new aerosol-on-demand print head. Copyright © 2021 American Association for Aerosol Research

We present design and manufacture of a 3D printed varifocal freeform optics. The optical refraction power can be tuned continuously by mutual rotation of two helically shaped lens bodies of azimuthally varying curvatures. Since no additional space for axial or lateral lens movement is required, rotation optics allow for a highly compact design of varifocal optics. Manufacturing of the optics was conducted by means of a high-resolution additive manufacturing process. Results of tactile surface measurements are presented as well as imaging through the lens.

This paper describes the application of a modeling approach for precise optical performance prediction of free-form optics-based subsystems on a demonstration model of an eye implant. The simulation model is enhanced by surface data measured on the free-form lens parts. The manufacturing of the free-form lens parts is realized by two different manufacturing processes: ultraprecision diamond machining and microinjection molding. Evaluation of both processes is conducted by a simulation of the optical performance on the basis of their surface measurement comparisons with the nominal geometry. The simulation results indicate that improvements from the process optimization of microinjection molding were obtained for the best manufacturing accuracy.

The densely innervated human cornea is the only superficial tissue of the human body in which nerve fibres are accessible in vivo by corneal confocal microscopy (CCM). Morphological parameters of the corneal sub-basal nerve plexus (SNP) derived from CCM images can potentially serve as a sensitive biomarker for early diagnosis of various neurodegenerative diseases. The evaluation of a single image with a typical field of view of 0.16 mm² is insufficient for robust morphometric assessment. Mosaicking approaches have therefore been proposed to examine the SNP on a larger scale. Here we present a highly automated technique that significantly facilitates the generation of mosaic images of the SNP and is suitable for clinical tests.