A Unified Interactive Python Platform for Teaching Wave Optics: From Fraunhofer Diffraction to Resolution Limits

Abstract Diffraction is a fundamental phenomenon in wave optics, yet its abstract mathematical formulation-particularly the transition from single-slit diffraction to circular aperture diffraction and Babinet's principle-often poses significant conceptual challenges for undergraduate students. Traditional lecture-based instruction, relying heavily on analytical derivations and static diagrams, frequently fails to provide students with an intuitive grasp of how aperture geometry determines diffraction patterns and how the Rayleigh criterion sets the fundamental limit of optical resolution. To address these challenges, we develop an integrated Python-based interactive teaching toolkit comprising three complementary simulation modules: a multi-shape diffraction simulator supporting single-slit, circular, square, and rectangular apertures; a filament diameter measurement tool based on Babinet's principle with built-in uncertainty propagation; and a Rayleigh criterion explorer that visualizes the continuous transition from unresolved to resolved two-point images. Built with PyQt5 and Matplotlib, and underpinned by NumPy and SciPy, the toolkit allows students to adjust key physical parameters-wavelength, aperture size, screen distance, and object separation-in real time and observe corresponding changes in diffraction patterns, intensity profiles, and resolution status. A real-time Fresnel-number diagnostic alerts users when the far-field approximation becomes invalid, fostering critical reflection on the domain of applicability of theoretical models. The simulations render abstract concepts such as Fraunhofer diffraction, Airy disk formation, Babinet's principle, and the Rayleigh criterion more tangible, while also promoting active learning and quantitative experimental reasoning. We present this toolkit as a low-cost, platform-independent resource for integrating computational physics into the undergraduate optics curriculum.