Problem 8 In a compact disc (CD), digital information is stored as a sequence of raised surfaces called "pits" and recessed surfaces called "lands." Both pits and lands are highly reflec- tive and are embedded in a thick plastic material with index of refraction n = 1.55 (Fig. 34–34). As a 780-nm wave- length (in air) laser scans across the pit-land sequence, the transition between a neighboring pit and land is sensed by monitoring the intensity of reflected laser light from the CD. At the moment when half the width of the laser beam is reflected from the pit and the other half from the land, we want the two reflected halves of the beam to be 180° out of phase with each other. What should be the (minimum) height difference t between a pit and land? [When this light enters a detector, cancellation of the two out-of-phase halves of the beam produces a minimum detector output.] Reflecting "pit" Reflecting "land" Plastic AndY rdgil nwon ani ai dignolov often o is ni tm n = 1.55 pbirdi ods ai jailW murtosqa o oulev 15 FIGURE 34-34 Problem 65. yamic and biM Laserabgqu2 beam

Problem 8 In a compact disc (CD), digital information is stored as a sequence of raised surfaces called "pits" and recessed surfaces called "lands." Both pits and lands are highly reflec- tive and are embedded in a thick plastic material with index of refraction n = 1.55 (Fig. 34–34). As a 780-nm wave- length (in air) laser scans across the pit-land sequence, the transition between a neighboring pit and land is sensed by monitoring the intensity of reflected laser light from the CD. At the moment when half the width of the laser beam is reflected from the pit and the other half from the land, we want the two reflected halves of the beam to be 180° out of phase with each other. What should be the (minimum) height difference t between a pit and land? [When this light enters a detector, cancellation of the two out-of-phase halves of the beam produces a minimum detector output.] Reflecting "pit" Reflecting "land" Plastic AndY rdgil nwon ani ai dignolov often o is ni tm n = 1.55 pbirdi ods ai jailW murtosqa o oulev 15 FIGURE 34-34 Problem 65. yamic and biM Laserabgqu2 beam

University Physics Volume 3

17th Edition

ISBN:9781938168185

Author:William Moebs, Jeff Sanny

Publisher:William Moebs, Jeff Sanny

Chapter3: Interference

Section: Chapter Questions

Problem 93CP: Figure 3.14 shows two 7.50-cm-long glass slides illuminated by pure 589-nm wavelength light incident...

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