"Water droplets forms spherical surface due to the surface tension, and changing the size of droplets can vary the radius. In this paper, the availability of a droplet as a lens was investigated by applying for laser processing. Silica glass was used as a workpiece. Defocused ArF excimer laser beam was irradiated to the glass with / without droplets respectively. As a result, the laser beam could be focused by the droplets and caused cracks inside of the glass not at the surface. Changing the size of the droplets and the wettability of the glass enables to control focal length. Aspheric droplets formed by varying the wettability of the glass surface spatially, can control the laser beam intensity distribution. Many small droplets on the glass surface condensed by cooling enables to reduce the threshold of the laser fluence to process and enhance the processing speed."
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