Controlled caustic-beam laser cleaning of curved surfaces via freeform mirror shaping

In industrial operations, pipelines that transport liquid organics must be periodically cleaned. Combining laser cleaning with conventional techniques can significantly reduce environmental impact, yet existing approaches rely on galvanometer mirrors to reshape the focal spot into a line. To simplify the optical path, we present a mirror-only scheme that molds the incoming beam directly into a uniformly curved line focus. By extending current transmission-based caustic-beam control to reflection, we design a freeform mirror that converts the Gaussian output of a fiber laser into an energy-uniform curved line segment. This line conforms to both inner and outer pipe surfaces, making it suitable for real-world cleaning tasks. Simulations confirm the high uniformity of the generated curved focus, yielding excellent results.