Previously, a novel sub-micron shock imprinting technique based on explosive-derived underwater shock waves was developed. In general, an underwater shock wave, whose high-pressure duration is considerably larger than that of laser-induced shock waves, can imprint higher quality sub-micron reliefs from a mold onto a foil surface compared to that achievable through conventional laser shock imprinting. To realize large-area imprinting, the size of the explosives must be increased. However, the detonation of explosives usually starts at one end, and if the dimensions of the explosives are increased, the metal foil may be compressed into a mold by an oblique shock wave. Nevertheless, the imprinting using oblique shock waves has not been examined. Therefore, in this study, a linear explosive was used to generate an oblique underwater shock wave and compress a 10 μm thick Al foil into a plastic mold. The oblique shock wave was evaluated through optical observation using a high-speed video camera and numerical simulation. The recovered reliefs exhibited a molding depth of 62% relative to the mold. The proper placement of the explosives could alleviate the production size limitation. The proposed technique can facilitate the realization of outdoor applications for metasurface materials.
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