PHY 2020 Lecture Notes - Lecture 47: Geometrical Optics, Diffraction, The Slits
Document Summary
According to geometric optics, when an opaque object is placed between a point light source and a screen, the shadow of the object forms a perfectly sharp line. However, the wave nature of light causes interference patterns, which blur the edge of the shadow. Geometric optics predicts that this situation should produce a sharp boundary between illumination and solid shadow. This photograph was made by placing a razor blade halfway between a pinhole, illuminated by monochromatic light, and a photographic film. The film recorded the shadow cast by the blade. Note the fringe pattern around the blade outline, which is caused by diffraction. Photograph of a razor blade illuminated by monochromatic light from a point source (a pinhole). Note: there is no fundamental distinction between interference and diffraction, but both are the consequence of superposition and huygen"s principle. Predicted outcome: geometric optics predicts that this setup will produce a single bright band the same size as the slit.
