Three-dimensional holographic parallel focusing with feedback control for femtosecond laser processing

We demonstrate feedback control of three-dimensional (3D) parallel focusing for automatic compensation of imperfections in an optical system and long-term stability of parallel focusing. These are realized by a computer generated hologram (CGH) displayed on a spatial light modulator (SLM), and an iterative calculation based on the observation of the 3D focusing intensities with an image sensor on a programmable linear stage. We demonstrate our parallel laser processing method using 40 parallel beams focused at four different planes, with a maximum uniformity of 0.96, applied to single-shot 3D fabrication in transparent glass.

Automated summary

Feedback control and computer-generated holograms enable automatic compensation for imperfections and long-term stability in parallel focusing. Demonstrating success in single-shot 3D fabrication in transparent glass proves the effectiveness of this parallel laser processing method.