1. CD and DVD Technology using laser light to reproduce music and movies

2. CD and DVD Technology Background Information Light waves are at the center of DVD and CD technologies. Two important concepts associated with light are useful. Wavelength Frequency

3. CD and DVD Technology Lambda ( ) is the usual Greek letter used to represent wavelength. Background Information The wavelength of any wave is the distance between two identical consecutive locations on that wave. The value for the wavelength is usually measured from one center location to the next or from one peak to the next. Wavelengh is a distance measurement and is reported in length units. 4.5

4. CD and DVD Technology Lambda ( ) Background Information The wavelength of any wave is the distance between two identical consecutive locations on that wave. The wavelengh of light waves we can see are very short. These lengths are measured in the nanometer length range. 1 meter = 1 X 10 9 nanometers (If you walk 1 meter you have also walked 1 billion nanometers.)

5. CD and DVD Technology Lambda ( ) Background Information The wavelength of any wave is the distance between two identical consecutive locations on that wave. (If you walk 1 meter you have also walked 1 billion nanometers.) The wavelength of this yellow-orange light wave is 6 X 10 -7 meters 6 X 10 2 nm 6 X 10 -7 m 1 X 10 9 nm 1 m = 1 meter = 1 X 10 9 nanometers6 X 10 2 nm = 600 nanometers

6. CD and DVD Technology Lambda ( ) Background Information The frequency of any wave is the number of wave cycles (number of wavelengths) that pass a given point in a second of time. 4.5 Assuming it took 1 second for the wave to move past this vertical marker, the frequency of this wave is 4.5 cycles seconds or 4.5 Hertz

7. CD and DVD Technology Lambda ( ) Background Information The connection between the frequency of a wave and the wavelength of the same wave is the speed the wave is moving in the forward direction. 4.5

8. CD and DVD Technology Lambda ( ) Background Information The connection between the frequency of a wave and the wavelength of the same wave is the speed the wave is moving in the forward direction. 4.5 c = speed of light (m. s -1 or m/s) f = frequency (1/s or s -1 ) = wavelength (m) For a light wave

9. CD and DVD Technology An application for a light emitting diode (LED) Signal Source for CD and DVD Technology Signal Source for CD

10. CD and DVD Technology A single wavelength (monochromatic) light wave is used in a CD player to “read” the music “off” of the CD. Signal Source for CD If the LED red light in your CD player has a frequency 3.84 x 10 15 Hz, what is the wavelength of this red light emitting diode? Engineers have to know the wavelength value of this monochromatic light before a CD play can be manufactured. Before the operation of a CD is discussed, it will be helpful to calculate the wavelength of the red light used in CD players.

11. CD and DVD Technology f = 3.84 x 10 15 Hz Hz = 1/s (s -1 ) c = 3.00 x 10 8 m/s 1 x 10 9 nm = 1 m Known(s): Unknown(s): Equation(s): in meters in nanometers If the LED red light in your CD player has a frequency 3.84 x 10 15 Hz, what is the wavelength of this red light emitting diode? Signal Source for CD

12. CD and DVD Technology f = 3.84 x 10 15 Hz Hz = 1/s (s -1 ) c = 3.00 x 10 8 m/s 1 x 10 9 nm = 1 m Known(s): Unknown(s): Equation(s): in meters in nanometers If the LED red light in your CD player has a frequency 3.84 x 10 15 Hz, what is the wavelength of this red light emitting diode? Signal Source for CD Solution: 3.00 x 10 8 m/s 3.84 x 10 15 s -1 =

13. CD and DVD Technology A cd player uses a red laser with a wavelength of 781 nm. If the LED red light in your CD player has a frequency 3.84 x 10 15 Hz, what is the wavelength of this red light emitting diode? Signal Source for CD Solution: (red) = 7.81 x 10 2 nm or 781 nm = 7.81 x 10 –7 m 3.00 x 10 8 m/s 3.84 x 10 15 s -1 =

14. CD and DVD Technology What is a Compact Disc What is a Compact Disc (CD)?

15. CD and DVD Technology A CD is a piece of clear polycarbonate plastic impressed with microscopic bumps in a grove which acts as a single, continuous, spiral track of data. After the polycarbonate has been formed, a thin, reflective layer of aluminum is sputtered onto the disc. Next, a thin, protective layer of acrylic is sprayed over the aluminum. The CD label is then printed onto the acrylic. What is a Compact Disc

16. CD and DVD Technology A CD player uses a laser to read the data from the bumps on the CD. The laser beam passes through the polycarbonate layer of the CD and reflects off of the aluminum layer onto an optical sensor. How a CD Works The bump reflects light differently than the rest of the aluminum layer and the optical sensor detects these changes.

17. CD and DVD Technology How does a CD Work These changes in light signal the electronics in the drive to read the data off of the bumps and interpret it into either the sound you hear coming from your speakers or the image you see on your computer screen.

18. CD and DVD Technology What is a DVD Disc Application - Digital Video Disc Technological advances have allowed engineers to make the data storage bumps on a DVD smaller and closer together than those on a CD. By itself, this advancement in precision increases the storage capacity of a DVD to 4.5 times that of a CD. The storage capacity of a DVD can be even greater because a DVD can have up to four layers of data storage bumps, two on each side of the disc.

19. CD and DVD Technology The DVD Player A DVD player reads data from a DVD the same way that a CD player reads data from a CD. The wavelength of the laser in a DVD player is 450 nm, a CD player uses a laser with a wavelength of 780 nm. Since the data storage bumps are smaller and closer together, a DVD player must use a laser with a smaller wavelength than the one used in a CD player. Digital Video Disc application

20. CD and DVD Technology You just learned that the laser in a DVD player has a wavelength of 450 nm. What is the frequency of this laser in Hz? Signal Source for DVD DVD Laser Frequency?

21. CD and DVD Technology Signal Source for DVD Known(s): Unknown(s): Equation(s): f in Hertz Hz = 1/s (s -1 ) = 4.50 x 10 -7 m c = 3.00 x 10 8 m/s DVD Laser Frequency?

22. CD and DVD Technology Signal Source for DVD Known(s): Unknown(s): Equation(s): f in Hertz Hz = 1/s (s -1 ) = 4.50 x 10 -7 m c = 3.00 x 10 8 m/s Solution: 3.00 x 10 8 m/s 4.50 x 10 -7 m f = DVD Laser Frequency?

23. CD and DVD Technology DVD Laser Frequency? Signal Source for DVD Solution: 3.00 x 10 8 m/s 4.50 x 10 -7 m f = The blue laser in a DVD player operates at a frequency of 6.67 x 10 14 Hz. f = 6.67 x 10 14 Hz (blue)

24. CD and DVD Technology