Reducing beam tracking complexity using a phase ramp and Fresnel lens when steering beams using spatial light modulators.

Steering multiple laser beams using spatial light modulators (SLMs) creates unwanted diffraction and reflections that are not modulated by the SLM, which can make beam tracking difficult. A novel, to the best of our knowledge, and simple beam steering methodology is proposed, which aims at reducing the influence of this clutter while maintaining tracking performance. The beam(s) are deliberately defocused before steering with a superposition of a phase ramp and Fresnel lens (PRFL) phase screen on the SLM.

Intercomparison of flux-, gradient-, and variance-based optical turbulence ( 2) parameterizations.

For free-space optical communication or ground-based optical astronomy, ample data of optical turbulence strength ( 2) are imperative but typically scarce. Turbulence conditions are strongly site dependent, so their accurate quantification requires in situ measurements or numerical weather simulations. If 2 is not measured directly (e.

Π-ML: a dimensional analysis-based machine learning parameterization of optical turbulence in the atmospheric surface layer.

Turbulent fluctuations of the atmospheric refraction index, so-called optical turbulence, can significantly distort propagating laser beams. Therefore, modeling the strength of these fluctuations ( 2) is highly relevant for the successful development and deployment of future free-space optical communication links. In this Letter, we propose a physics-informed machine learning (ML) methodology, Π-ML, based on dimensional analysis and gradient boosting to estimate 2.

Actuation profiles to form Zernike shapes with a thermal active mirror.

In EUV lithography, the absorption of EUV light causes wavefront distortion that deteriorates the imaging process. An adaptive optics system has been developed ["Adaptive optics to counteract thermal aberrations," Ph.D.