In this study, we demonstrated removal processing inside polydimethylsiloxane (PDMS) using a short-pulse laser without a photomask. As a light source, a passive Q-switched Nd:YAG laser was used, with a wavelength of 1064 nm and a pulse width of 500 ps.We fabricated micro cavities with a rectangular shape and complex three-dimensional structure. In addition, the fabricated cavity was cut with a cutter knife and the cross section was observed with scanning electron microscopy in order to investigate the processing characteristics in this experimental system. From the observation of the cavity's cross section, we found that the height was smaller than the design value and the upper wall was bent. We considered that thermal expansion during laser processing was the origin. By simulta-neously slowing down the stage moving speed and repetition rate, the degree of bending was able to be decreased. Although there was bending of the cross section, we fabricated cavities with a rectan-gular shape and a complex three-dimensional structure.
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