New insights on the knife edge technique of laser beam characterization

Precise characterization of laser beam parameters is essential for applications in optical metrology, material processing, and nonlinear optics. This work presents a systematic experimental study of the knife-edge technique (KET) for Gaussian beam profiling, with particular focus on the sensitivity of the method to misalignment and mechanical imperfections. Two approaches for beam waist estimation are compared: a nonlinear fit to the theoretical error function and the conventional 10 to 90% width approximation. The nonlinear fitting approach provides more consistent and robust results, with lower dispersion and better tolerance to minor alignment deviations. Additionally, alignment stability metrics based on the evolution of the beam center position were implemented to quantify the influence of mechanical artifacts and misalignment. The results confirm that the KET, combined with proper data analysis, allows reliable reconstruction of beam parameters even under non-ideal experimental conditions.