Dynamic Beam Shaping Architecture for High-Energy Lasers

Dynamic beam shaping has recently emerged as a new frontier in high-power laser systems for advanced industrial material processing. Through the inclusion of adaptive optics elements, the spatial intensity profile of laser beams becomes a new parameter to improve in real-time the thermal and mechanical interactions with the workpiece. A wide range of applications require high-power or high-energy lasers: the technology employed in cutting, welding, surface treatment, and additive manufacturing sees a continuous evolution in terms of process efficiency, quality, and versatility. However, the potential of static beam shaping methods is strongly limited by the susceptibility to light intensity variation of the input laser beam and real-time process phenomena. In this context, deformable mirrors (DMs) present a promising solution to actively tailor wavefronts and correct aberrations at high-spatial frequency. Despite their proven effectiveness in fields such as astronomy, microscopy, and biomedical imaging, the integration of DMs into high-power laser optical chains is not straightforward. Key difficulties include managing thermal loads, achieving the desired intensity shape, and implementing a robust, real-time control aligned to the stringent industrial requirements. This thesis focuses on the design and implementation of a basic optical chain incorporating a deformable mirror for dynamic beam shaping in high-energy laser systems. The primary objective is to develop an adaptive optics-based solution capable of real-time modulation of beam profiles, enabling tailored energy distribution to optimize laser-material interactions. The research combines theoretical optical design, numerical simulations, and experimental validation to address the complexities of DM integration. Optical simulations based on geometric optics and physical optics propagation are employed to optimize the optical chain, ensuring minimal aberrations on the source beam and efficient modulation at the focus. The deformable mirror’s behaviour is modelled in Zemax OpticStudio and through Python packages as a continuous phase plate, which add aberrations defined as a linear combination of Zernike polynomials. An experimental test bench is constructed to evaluate the DM’s dynamic response and beam shaping capabilities in practical scenarios. The influence of low and high order modes, such as defocus, astigmatism, coma, quadrifoil, pentafoil and spherical aberrations, is evaluated to obtain common intensity profiles (top-hat, ellipse, doughnut). Results demonstrate that the introduction of a DM enables significant enhancements in beam shaping flexibility, allowing quick adjustments of beam profiles, tailored to specific industrial processing needs. The real-time feedback, realized by a CMOS wavefront sensor, enables the active driving of the mirror in a zonal or in a modal way. This method is a starting point for the development of smarter laser manufacturing systems capable of higher precision, reduced processing times, and improved material properties. In conclusion, the designed dynamic beam shaping system represents an intriguing possibility in high-energy laser technology with significant implications for industrial material processing. By harnessing the potential of deformable mirrors within an optimized optical chain, this work aims to improve the efficiency and versatility of the optical chain, supporting the goals of Industry 4.0 and beyond.