Simplified, high-precision laser-micro-drilling using trepanning optics with micro-structured mirrors

This robust trepanning optics with only one rotating element (grid mirror) offers great flexibility with regard to the realizable drill diameter/ geometry range and also simplifies setup and calibration of the system. Negatively conical and complex geometries of high precision can be produced without post-processing.

Today, geometries inside a component no longer have to follow the cylindrical geometry of a mechanical drill. It has long been possible to produce precisely shaped cavities of complex shapes by removing the material at specific points using laser energy - even at hard-to-reach spots.

In conventional trepanning systems, several elements (wedge plates, or cylindrical lenses) rotate, which makes the installation itself as well as the setup and calibration of such a system complex and time consuming. Therefore, there is high potential for optimization in terms of efficiency and user-friendliness.

The concept of grating-based trepanning optics directs the laser focus in the desired direction solely by rotating a diffraction grating. The gratings can be deigned to be operated in reflection or in transmission. Nevertheless, the working principle is the same. This setup enables the efficient production of holes by a much more robust and cost-effective trepanning system. The concept also offers greater flexibility in terms of the range of hole sizes. Furthermore, it requires components that are easy to manufacture (a diffraction grating with low aspect ratio).
The special advantage lies in the robustness as well as in the simplified setup and operation of the system. It can also be designed in different configurations.

• simple, robust construction - only one rotating component
• simplified setup and operation - easy to align
• low-cost production of the components by means of well-established lithography and etching processes
• highly precise, time and cost efficient

This trepanning concept developed at the Institut für Strahlwerkzeuge (University of Stuttgart) now allows for a significantly simplified design of such a laser drilling system. In combination with custom-designed grating mirrors, also developed by the same team, a new trepanning optics system can be realized. It can produce negatively conical and complex geometries of high precision without post-processing; at the same time, setup and operation become easier.