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1
A diffraction grating consists of a large number of
equally spaced narrow slits or lines. A transmission
grating has slits, while a reflection grating has lines that
reflect light.
The more lines or slits there
are, the narrower the peaks.
Physics 208N004 Lecture #35
– 15 April 2011
Chapter 37: 2, 3 Photon Properties
357 Diffraction Grating & Ch 35 Summary
The maxima of the diffraction pattern are defined by
357 Diffraction Grating
Example 358: Diffraction grating: lines.
Determine the angular positions of the first and second
order maxima for light of wavelength 400 nm and 700 nm
incident on a grating containing 10,000 lines/cm.
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357 Diffraction Grating
Example 359: Spectra overlap.
White light containing wavelengths from 400 nm to 750
nm strikes a grating containing 4000 lines/cm. Show
that the blue at
λ
= 450 nm of the thirdorder spectrum
overlaps the red at 700 nm of the second order.
Conceptual Example 3510: Compact disk.
When you look at the surface of a music CD, you see the
colors of a rainbow. (a) Estimate the distance between
the curved lines (to be read by the laser). (b) Estimate
the distance between lines, noting that a CD contains at
most 80 min of music, that it rotates at speeds from 200
to 500 rev/min, and that 2/3 of its 6cm radius contains
the lines.
•
Light bends around obstacles and openings in its
path, yielding diffraction patterns.
•
Light passing through a narrow slit will produce a
central bright maximum of width
•
Minima occur at
Summary of Chapter 35
•
Diffraction limits the resolution of images.
•
Diffraction grating has many parallel slits or lines;
peaks of constructive interference are given by
•
Polarized light has its electric field vectors in a
single plane.
3
•
The intensity of planepolarized light is reduced after it
passes through another polarizer:
•
Light can also be polarized by reflection; it is
completely polarized when the reflection angle is the
polarization angle:
Summary of Chapter 35
2
0
cos
.
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This note was uploaded on 09/18/2011 for the course PY 208M 87878 taught by Professor George during the Spring '09 term at N.C. State.
 Spring '09
 GEORGE

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