Which colour laser beam is used in CD and DVD?

Initially, CD lasers with a wavelength of 780 nm, which is within infrared range, were used. For DVDs, the wavelength was reduced to 650 nm (red color), and the wavelength for Blu-ray Disc was reduced to 405 nm (violet color).

What color is the laser that reads a CD?

The laser (red) flashes up onto the shiny (under) side of the CD, bouncing off the pattern of pits (bumps) and lands (flat areas) on the disc. The lands reflect the laser light straight back, while the pits scatter the light.

What laser do CDs and DVDs use?

LaserDisc

A LaserDisc (left), with a DVD for size comparison
Read mechanism 780 nm wavelength semiconductor laser (early players used HeNe gas lasers)
Write mechanism Laser on dye; same write mechanism as recordable CD/DVDs
Standard LaserVision
Developed by Philips, MCA Inc., Pioneer Corporation

What laser does a CD use?

A CD is read by focusing a 780 nm wavelength (near infrared) semiconductor laser through the bottom of the polycarbonate layer. The change in height between pits and lands results in a difference in the way the light is reflected.

Why do laptops no longer have CD drives?

Size is of course the most obvious reason that they’ve essentially disappeared. A CD/DVD drive takes up a lot of physical space. The disc alone requires at least 12cm x 12cm or 4.7″ x 4.7″ of physical space. As laptops are made to be portable devices, space is extremely valuable real estate.

IMPORTANT:  Does cache matter on a hard drive?

Can a DVD drive read a CD?

DVDs had greater capacity and performance. DVD-ROM drives can read CD-DA, CD-ROM, and CD-R/RW discs, but they also read DVD-Video, DVD-ROM, and (sometimes) DVD-Audio discs.

What is the difference between CD R and CD-RW?

A Compact Disc Recordable (CD-R) is a Write Once Read Multiple (WORM) disc. These discs can only record data once and then the data becomes permanent on the disc. … A Compact Disc Re-Writable (CD-RW) is an erasable disc that can be reused. The data on a CD-RW disc can be erased and recorded over numerous times.

How long do CDs last?

The relative stability of optical disc formats

Optical disc formats Average longevity
CD (read-only, such as an audio CD) 50 to 100 years
CD-RW (erasable CD) 20 to 50 years
BD-RE (erasable Blu-ray) 20 to 50 years
DVD+R (silver alloy metal layer) 20 to 50 years

Where can I burn a CD?

Where Can I Burn a CD? 4 Places That Burn CDs for You Listed

  • FedEx.
  • Staples.
  • Office Depot/OfficeMax.
  • Local Businesses.
  • Public Libraries.

How are DVDs better than CDs?

The nearly six times extra storage of the DVD is the main differentiator between the two. CDs had their short heyday before the DVD hit the market, and since most music albums can fit easily onto a CD, it became the norm for storing tunes.

Information storage methods