Regensburg 2019 – wissenschaftliches Programm
O 3.1: Vortrag
Montag, 1. April 2019, 10:30–10:45, H5
Laser Actuation of Micro Cantilevers via Thermo-Mechanical Symmetry Breaking — •Sven Kraft, Boris Hage, Ingo Barke, and Sylvia Speller — Institute of Physics, University of Rostock, 18051 Rostock
Direct actuation of Atomic Force Microscopy (AFM) cantilevers by a laser beam is particularly useful for liquid environments . Various mechanisms are proposed in the literature how laser irradiation leads to mechanical cantilever excitation [2-4]. We present a systematic and comprehensive study of the spatially and frequency resolved excitation efficiency by mapping the oscillation amplitude and phase as a function of the location of an intensity modulated laser. We observe a rich mode structure with surprisingly efficient excitation at the edges, as well as multiple phase reversals in transversal direction of the cantilever, resulting in a checkerboard-like phase pattern. A comparison of coated and uncoated cantilevers, and of illumination from the top and bottom side reveals anisotropic thermal deformation being the dominant mechanism of actuation. This is corroborated by analytical calculations based on solid mechanics which take into account the cross sectional shape of the cantilevers. We also discuss the effect of an internal light intensity structure due to multiple reflection within the cantilever.