Laser Cutting of Thin Gold Foils

摘要

The AIDA detector (Advanced Impact Detector Assembly) is a device for the in-situ measurement of the kinetic energy of micrometer-sized particles in space. Structured gold foils of 50 μm in thickness are used here as absorber arrays, cut by laser ablation. A total detection area of about 33 cm~2 is divided into 256 squared elements, lateral length 3.6 mm, in a 16×16 array. The connecting ligaments are of approx. 20 μm in width. During processing, the pulsed UV laser and the custom built positioning system are synchronized by the encoder signal of the high precision stages to provide for geometrical accuracy. A challenge is the fixture and handling of the gold foils to avoid mechanical and thermal deformation of the very sensitive structures and to minimize adhering debris. A novel procedure is presented to solve these tasks by using capillary forces on the fixed surface and a protecting film on the free surface of the foil by means of a single fluid. The cutting process is controlled in-situ. As a result, the microstructured foil is clean, distortion low, and the foil can be fixed on a silicon-based thermopile array.