Beam Shaping of VCSEL Arrays Using Randomized Microlens Arrays with Integrated Collimation
- In active 3D imaging systems, the circular, Gaussian-shaped output of VCSEL arrays must be converted into rectangular patterns aligned with the camera’s field of view. To maximize energy efficiency, the beam edges must be sharply confined to avoid illumination outside the target area. For this purpose, this work presents the design, fabrication, and experimental evaluation of randomized microlens arrays (RMLAs) and the novel collimating RMLAs (cRMLAs), which are tailored specifically to the emission characteristics of VCSEL arrays. The freeform optical elements were fabricated using grayscale two-photon polymerization and verified using confocal microscopy. Far-field beam profiles were recorded with a cost-efficient, camera-based setup and analyzed with respect to efficiency, field-of-view coverage, and intensity distribution. The results show that the cRMLAs offer a significant increase in beam shaping efficiency and spatial resolution. This represents the first monolithic randomized microlens array with integrated collimation. The approach enables compact and energy-efficient beam shaping in future active sensing systems.
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| Document Type: | Article |
|---|---|
| Language: | English |
| Author: | Elias Ellingen, Robert Lange |
| Parent Title (English): | IEEE Photonics Journal |
| Volume: | 17 |
| Issue: | 5 |
| Article Number: | 2201209 |
| Number of pages: | 9 |
| ISSN: | 1943-0647 |
| URN: | urn:nbn:de:hbz:1044-opus-91955 |
| DOI: | https://doi.org/10.1109/JPHOT.2025.3603888 |
| Publisher: | IEEE |
| Publishing Institution: | Hochschule Bonn-Rhein-Sieg |
| Date of first publication: | 2025/08/28 |
| Copyright: | © 2025 The Authors. This work is licensed under a Creative Commons Attribution 4.0 License. |
| Funding: | This work has been partially funded by the German Federal Ministry of Research, Technology and Space, funding code 13FH554KX1, and the Institute for Safety and Security Research at the Bonn-Rhein-Sieg University of Applied Science |
| Tag: | Beam Shaping; VCSEL arrays; collimating optics; freeform optics; microlens arrays; two-photon polymerization |
| Departments, institutes and facilities: | Fachbereich Ingenieurwissenschaften und Kommunikation |
| Institut für Sicherheitsforschung (ISF) | |
| Institut für Technik, Ressourcenschonung und Energieeffizienz (TREE) | |
| Projects: | ROSE3D - FH-Kooperativ 2-2022: Robustes und sicheres 3D Kamera System (DE/BMBF/13FH554KX1) |
| Dewey Decimal Classification (DDC): | 5 Naturwissenschaften und Mathematik / 53 Physik / 535 Licht, Infrarot- und Ultraviolettphänomene |
| Entry in this database: | 2025/09/05 |
| Licence (German): |  Creative Commons - CC BY - Namensnennung 4.0 International |
