Another example is the rainbow pattern we see on the surface of a CD or DVD—in this case, the closely spaced tracks on the disc act as a diffraction grating.
The effect of diffraction from an opaque object can be seen as interference between different parts of the wave beyond the diffraction object.
In 1803, Thomas Young did his famous experiment observing diffraction from two closely spaced slits.
Most diffraction phenomena can be understood in terms of a few simple concepts that are illustrated below.
James Gregory (1638–1675) observed the diffraction patterns caused by a bird feather, which was effectively the first diffraction grating.
The center part of the wave shows limited effects at short distances, but exhibits a stable diffraction pattern at longer distances.
Diffraction refers to various phenomena associated with wave propagation, such as the bending, spreading and interference of waves passing by an object or aperture that disrupts the wave.
The very heart of the explanation of all diffraction phenomena is interference between waves.
The most conceptually simple example of diffraction is single-slit diffraction in which the slit is narrow, that is, significantly smaller than a wavelength of the wave.
Slits significantly wider than a wavelength will also show diffraction that is most noticeable near their edges.