Optical disc (CD/DVD)
part · 1982 · Digital age
Data is read by a laser.
Principles and materials it uses
- Laser diode — uses. Read by a laser.
- Reflection of light — uses. Reflection from the pits.
- Wave interference — uses. The pits cancel the reflected beam by interference — that is how zeros and ones are read.
- Plastic — is made of. The disc is polycarbonate.
- Aluminium — is made of. The reflective layer is aluminium.
What it is a kind of
- Compact disc — includes. An optical disc.
- DVD — includes. An optical disc.
Things built in a similar way
- Diffraction grating — works like. The tracks of a CD split light into a rainbow.