What is the diffraction When light passes through a narrow slit it spreads out more than what could be 天津大学精仪学院 accounted for by geometric construction This is an example of diffraction Diffraction can be defined as any departure from the predictions of geometric optics 天津大学作 242 When light passes through a narrow slit, it spreads out more than what could be accounted for by geometric construction. This is an example of diffraction. Diffraction can be defined as any departure from the predictions of geometric optics. What is the Diffraction?