The glass original from which copies of CDs, DVDs, or Blu-rays can be created.
Recording the data from a CD, DVD, or Blu-ray onto a photosensitive surface on a glass disc (the master) used for continuous disc production.
A process which applies a thin metallic layer to the surface of the plastic disc after molding. The process takes place under a vacuum.
MID (Maximum Information Diameter)
Must be lower than 116mm. The MID parameter is an important measure because molding and processing result in very high probability of problems at the end of the track. The MID signal indicates the end of the disc. If the MID does not meet specifications, there is a danger that high frequencies in the track following signal will be weakened owing to birefringence, to scratches, or fingerprints left when handling.
A CD containing several tracks that are not the same type.
An optical disc recordable and erasable at will.
Approximately one million bytes.
NWA (Normalized Wobble Amplitude)
Relationship between the wobble signal and the Push Pull. The Orange Book specifies a NWA of between 0,035 and 0,05.
The standard for recordable CDs. It has two parts, one for CD-Rs and one for CD-RWs.
Real-time operating system used by the CD-Is.
PCM (Pulse Code Modulation)
Standard method for coding audio.
Recordable CD specially developed by Kodak to store photos and view them on CD-ROM/XA, Photo - CD or CDI readers. One CD can contain 100 photos.
Areas of the CD burnt by the laser beam in order to create a change in reflectivity.
An area at the end of a track with a minimum length of two seconds.
Area at the beginning of a track.
Preparing data to be recorded onto CD, DVD, or Blu-ray before continuous production.
Area of a disc where data is kept.
Test CD, DVD, or Blu-ray.
Protective layer of lacquer or polymer applied with a nozzle and baked under UV rays to protect the layers of dye and gold (or silver).
The Push Pull (PP) parameter is a measure of how easily the reader is able to follow the spiral. The PPa is the PP value after recording, which is compared to the reflective value of the spiral after recording (IGa). The same applies to the PPb (before recording with IGb). Particularly significant is the normalised Push - Pull ratio (NPPR) given by the following formula :
The NPPR must fall between 0.5 and 1. The Push-Pull is measured at 10 points in the data area of the disc. In CD-Cats system, the PP is measured with a linear polarized light. A measurement system using polarized light can modify results in a linear direction.