A novel method for laser micro drilling of holes with a higher geometrical accuracy

Laser percussion drilling of micro-holes has established itself as a prominent micro-machining technique rivalling both conventional and non-conventional micro-drilling processes. Despite its broader use, the laser percussion drilling process has some limitations, particularly the achievable micro-holes' accuracy. The research reports a novel method to address this shortcoming by improving the holes' dimensional and geometrical accuracy. Especially, the proposed two-side method for laser percussion drilling of micro holes utilizes a penetrating laser beam that is refocused at the hole exit by employing a reflective concave mirror lens. In this way, an additional ablation occurs at the hole exit to improve the hole accuracy. Especially, the exit size of the holes increases and simultaneously their cylindricity is improved while the tapering angle is reduced. Notably, these improvements are achieved without affecting the processing efficiency whereas the proposed laser drilling setup is relatively simple to implement.