English: The electron is illuminated from below by light depicted as both photons and waves, with wavefronts shown as blue lines. Photons that enter the microscope deviate from the vertical by an angle less than ε/2, and impart momentum to the electron as they scatter off it. The depiction of the wavefronts inside the microscope is unphysical due to diffraction effects that produce a blurred image and hence uncertainty in position.