FIG 8 - uploaded by Zander J Mausolff
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Laser light is emitted and passed through a diffraction grating creating 0 th and 1 st diffraction orders. The diffracted light is guided throuhgh a collimating lens and then focused onto the CD. Some optics that guide the reflected light have been omitted in this diagram.
Source publication
The examination of an off the shelf compact disk (CD) illustrates many concepts in optical
physics. The storage capacity of a compact disk was determined by directing light from a HeNe
laser onto a CD and viewing the resulting diffraction pattern. The distance between CD tracks
(track length) was determined to be 1.56µm ±0.032µm. With simple assump...
Context in source publication
Context 1
... that we understand how CDs are encoded we will look briefly at how CDs are read. Laser light goes through a diffraction grating and collimating lens to produce three parallel light rays, which are focused onto the CD as shown in Fig. 8. When these three rays encounter a pit, the center ray traverses 1 2 λ more than the other rays and destructively interferes with the adjacent rays. If these three rays do not encounter a pit they are reflected and captured by a photodiode ...
