Bonn 2025 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 74: Photonics II
Q 74.2: Talk
Friday, March 14, 2025, 14:45–15:00, HS Botanik
Speeding up the calculations of computer-generated holograms for complex 3D beam-shaping — •Tim-Dominik Gómez1, Daniel Flamm2, Pavel Ruchka1, and Harald Giessen1 — 14th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — 2Trumpf GmbH & Co KG, Ditzingen, Germany
Beams with spatially varying, non-Gaussian profiles are essential across diverse research fields, particularly in applications like imaging and material processing. These can be shaped with the help of diffractive or holographic optical elements, such as spatial light modulators or metasurfaces, which in many cases results in the restriction to phase-only optical elements. The resulting calculation of an appropriate phase mask for a specific 3D beam-shape necessitates the use of iterative Fourier transform algorithms (IFTA). For free-space propagation the number of 2D Fast Fourier transforms involved scale with the number of layers observed and is thus computationally intensive. For valid window sizes > 1024 pixel, even current-gen CPUs require more than a second for the computation of around 100 of these 2D FFTs.
In this work, we therefore simulate free-space propagation through upwards of 500 layers on a current-generation NVIDIA 4090 GPU utilizing the angular spectrum method. We then implement, as well as compare a variety of IFTAs, identifying valid approaches and parameters. Further, we optimize memory allocation and parallelization for these approaches and aim to enable real-time processing for the control of the optical traps in Rydberg quantum computers.
Keywords: holography; CGH; beam-shaping; metasurface; SLM