09-08-2012, 11:07 AM
CD-R, CD-RW, CD BURNER
[attachment=30699]
INTRODUCTION
CD is the type of “Optical Media” for transferring data. CD-R is short for “CD-Recordable” not “CD-ROM”. Recordable CDs are WORM (Write Once, Read Multiple). A related technology called CD-Rewritable (CD-RW) allows you to erase discs and reuse them.
A) The Bumps
CDs store music and other files in digital form that is; the information on the disc is represented by a series of 1s and 0s. In conventional CDs, these 1s and 0s are represented by millions of tiny bumps and flat areas on the disc's reflective surface.
To read this information, the CD player passes a laser beam over the track. When the laser passes over a flat area in the track, the beam is reflected directly to an optical sensor on the laser assembly.
B) The Path
The bumps are arranged in a spiral path, starting at the center of the disc. The CD player spins the disc while the laser assembly moves outward from the center of the CD.
The CD player spins the disc while moving the laser assembly outward from the middle.
Reading CDs
The CD fabrication machine uses a high-powered laser to etch the bump pattern into photo resist material coated onto a glass plate.
Conventional CDs have remained a "read only" storage medium for the average consumer, like LPs or conventional DVDs. To audiophiles accustomed to recordable cassettes, as well as computer users who were fed up with the limited memory capacity of floppy disks, this limitation seemed like a major drawback of CD technology.
Writing CDs
CD-recordable discs, or CD-Rs, don't have any bumps or flat areas at all. Instead, they have a smooth reflective metal layer, which rests on top of a layer of photosensitive dye.
When the disc is blank, the dye is translucent: Light can shine through and reflect off the metal surface.
By selectively darkening particular points along the CD track, and leaving other areas of dye translucent, you can create a digital pattern.
Burning CDs
A) Laser Assembly
CD burners darken microscopic areas of CD-R discs to record a digital pattern of reflective and non-reflective areas that can be read by a standard CD player.
The CD burner has a moving laser assembly, just like an ordinary CD player. But in addition to the standard "read laser," it has a "write laser." The write laser is more powerful than the read laser, so it interacts with the disc differently
B) Write Laser
The write laser moves in exactly the same way as the read laser: It moves outward while the disc spins.
The bottom plastic layer has grooves pre-pressed into it, to guide the laser along the correct path.
At 1x speed, the CD spins at about the same rate as it does when the player is reading it. This means it would take you about 60 minutes to record 60 minutes of music. At 2x speed, it would take you about half an hour to record 60 minutes, and so on.
[attachment=30699]
INTRODUCTION
CD is the type of “Optical Media” for transferring data. CD-R is short for “CD-Recordable” not “CD-ROM”. Recordable CDs are WORM (Write Once, Read Multiple). A related technology called CD-Rewritable (CD-RW) allows you to erase discs and reuse them.
A) The Bumps
CDs store music and other files in digital form that is; the information on the disc is represented by a series of 1s and 0s. In conventional CDs, these 1s and 0s are represented by millions of tiny bumps and flat areas on the disc's reflective surface.
To read this information, the CD player passes a laser beam over the track. When the laser passes over a flat area in the track, the beam is reflected directly to an optical sensor on the laser assembly.
B) The Path
The bumps are arranged in a spiral path, starting at the center of the disc. The CD player spins the disc while the laser assembly moves outward from the center of the CD.
The CD player spins the disc while moving the laser assembly outward from the middle.
Reading CDs
The CD fabrication machine uses a high-powered laser to etch the bump pattern into photo resist material coated onto a glass plate.
Conventional CDs have remained a "read only" storage medium for the average consumer, like LPs or conventional DVDs. To audiophiles accustomed to recordable cassettes, as well as computer users who were fed up with the limited memory capacity of floppy disks, this limitation seemed like a major drawback of CD technology.
Writing CDs
CD-recordable discs, or CD-Rs, don't have any bumps or flat areas at all. Instead, they have a smooth reflective metal layer, which rests on top of a layer of photosensitive dye.
When the disc is blank, the dye is translucent: Light can shine through and reflect off the metal surface.
By selectively darkening particular points along the CD track, and leaving other areas of dye translucent, you can create a digital pattern.
Burning CDs
A) Laser Assembly
CD burners darken microscopic areas of CD-R discs to record a digital pattern of reflective and non-reflective areas that can be read by a standard CD player.
The CD burner has a moving laser assembly, just like an ordinary CD player. But in addition to the standard "read laser," it has a "write laser." The write laser is more powerful than the read laser, so it interacts with the disc differently
B) Write Laser
The write laser moves in exactly the same way as the read laser: It moves outward while the disc spins.
The bottom plastic layer has grooves pre-pressed into it, to guide the laser along the correct path.
At 1x speed, the CD spins at about the same rate as it does when the player is reading it. This means it would take you about 60 minutes to record 60 minutes of music. At 2x speed, it would take you about half an hour to record 60 minutes, and so on.