Observation of radiation pressure induced deformation of high-reflective reflector

Abstract

In this paper, radiation pressure induced deformation of a series of thin aluminum reflectors is analyzed theoretically and experimentally. Theory of quantum mechanics and material mechanics are applied in 2D simulations and exhibits good coordination with experiment results. The original laser source used in the experiment is Gauss-distributed and has been shaped and expanded, resulting in the flattened light to avoid over heating or even ablation of the irradiated reflector, which can also bring a major deformation. The aluminum reflectors are fabricated by a high precision machine tool into a thickness of 100, 200, 300 μm with a surface roughness of 8 nm in Ra, and then coated with high-reflective coatings and mounted on a thick 3D printing base made of polylactic acid (PLA). In the experimental process, a vacuum chamber is employed to distinguish the effect of thermal convection. The results show that radiation pressure induced deformation has an obvious negative correlation with the reflector thickness. The time-deformation curve of the reflector reaches 2.4 μm peak negative displacement at most the moment laser beam is acting when under vacuum circumstance, and soon raises up to over 12 μm positive displacement if the reflector is continuously irradiated. Subsequent analysis shows that such negative displacement is induced by radiation pressure and the positive displacement is caused by thermal expansion of the PLA base.