Laser micro milling is a process whereby cavities and pockets can be created on the surface of a piece of material by laser ablation. Its main benefits over photo-etching are that laser micromachining can achieve very smooth surfaces whereas photo etching can only reveal the grain pattern that is rolled into the stock.
Laser micro milling is also used to put the finishing touches on very fine through slots, slots that cannot be made accurate enough by any other method.