Diffraction and Interference. Diffraction Huygen’s Principle Diffraction Lab. Light. Has wave properties. Can diffract. Can constructively or destructively interfere. Wave Fronts. Lines that are perpendicular to the motion of the wave.
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Diffraction and Interference
Has wave properties.
Can constructively or destructively interfere.
As the straight waves passed through a narrow hole, they spread out in a circular pattern.
Giving proof to the fact that every point on a wave front is a new source for a new set of wavelets.
Any bending of a wave around an obstacle or edges of an opening by means other than reflection or refraction.
Why would we ever want waves to bend past an obstruction?
Long AM radio waves can diffract around hills and buildings and can be received better in more places than short waves that don’t diffract as much.
Diffraction is bad when we want to see very small objects with microscopes.
If the size of the small object is the same as the wavelength of light, the image will be blurred by diffraction.
1801, Thomas Young discovered that when light of a single color (monochromatic) was directed through two closely spaced pinholes, fringes of brightness and darkness were produced on a screen.
Iridescence:The phenomenon whereby interference of light waves of mixed frequencies reflected from the top and bottom of thin films produces a spectrum of colors.
Same principles as Single-Color Interference
The shapes of the fringes for both are made by the differences in thickness of the materials.
Except we are using light of mixed frequencies and our fringes are made of different colors.
In a laser, a light wave emitted from one atom stimulates the emission of light from a neighboring atom so that the crests of each wave coincide. Thus a coherent beam.
So you see the 3-D image due to the way the hologram diffracts light and the way this diffracted light constructively and destructively interfere. In this way, holograms are like diffraction gratings.