1. DNA Diffraction
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2. X-ray diffraction and biomolecular structure
DNA x-ray diffraction
Diffraction by tungsten coil
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3. Light is an electromagnetic wave:
Diffraction
Diffraction results from the interference of an infinite number of waves emitted by a continuous distribution of source points.  According to Huygens' principle every point on a wave front of light can be considered to be a secondary source of spherical wavelets.  These wavelets propagate outward with the characteristic speed of the wave.  The wavelets emitted by all points on the wave front interfere with each other to produce the traveling wave. 
Refraction
Hygens’ Principle:
Every point on a wavefront can be considered a secondary point source. Wavelets emitted by all points on the wavefront interfere with each other to produce the final traveling wave.
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4. Diffraction of plane wave at large slit
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5. Diffraction of plane wave at small slit
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6. Water Waves
MIT Ripple Tank Demo
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7. Superposition Superposition of sinusoidal waves
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8. Single slit diffraction
Alternations regions of high/low intensity:
Constructive/Destructive Interference
path length difference, D:
= (n+1/2) l constructive
= n l destructive
(n = 0, 1, 2, …)
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9. Double slit interference
d sin q = m l constructive interference
d sin q = (m+1/2) l destructive interference
(m=0,1,2,….)
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10. Diffraction grating
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11. Convolution, pictorially
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