During optical encoding, pulses of a high power laser beam 'burn' microscopic 'pits' on the recording layer. The untouched spaces between such pits are called 'lands.' During the read process, the laser light focuses on the spinning spiral track, and since the pits reflect light less intensely, the read head detects the changes in reflectivity, and those transitions are processed as is to produce a binary data stream. In CD-ROM, the track pitch is 1.6 microns, and the pits are .83 microns wide. In DVD, the track pitch is 0.74 microns, and the pits are 0.4 microns wide. Maximum pit lengths are 10 times pit width.
Pits are spots on the vascular cells in plant cells that contain no secondary cell wall which aids in the passage of water through the cells walls. The pit membrane being impermeable to cavitation bubbles helps to localize cavitation during water stress in the plant. DIAGRAM: Pits Sclerenchyma PHOTO
An area of track separated from the start/finish straight by a wall, where the cars are brought for new tyres and fuel during the race, or for set-up changes in practice, each stopping at their respective pit garages.