Laser drilling of micro-holes with controllable taper using 355 nm nanosecond laser

It is a great technical challenge to fabricate micro-holes in hard materials, such as tungsten and diamond, especially for controllable taper angle and low heat affected zone. In this paper, a simple method employing a 355 nm nanosecond laser, as well as a dual-path circular scanning strategy are presented to overcome these challenges. This method can adjust the angle between the laser beam and the rotation axis by altering the angle of the tilt stage, thereby enabling the controlled machining of micro-holes with tapers ranging from negative to positive. Additionally, comparative experiments with traditional circular scanning strategies have demonstrated that the dual-path circular scanning strategy effectively improves the roundness, drilling efficiency, and sidewall quality of micro-holes by expanding the ablation area. Using this method and strategy, micro-holes with tapers ranging from −14.9° to 23.8° were successfully fabricated in 300 μm-thick tungsten. Furthermore, they were employed to prepare a series of high-quality micro-holes on a typical nonmetallic high-hardness material, diamond.