http://www.usa.canon.com/cusa/semiconductor/products/encoder_optolectronic_components/air_bearing/air_bearing_spindle_motor?pageKeyCode=writeReviewPage
Air Bearing Spindle Motor

Overview
Rotation Precision Exceeding Sub-Microns, High Rigidity, High Endurance, Canon's Air Bearings Have Them All.
Canon's air bearings, developed originally as a key component in super-high precision manufacturing technology, have a special structure that gives them superior characteristics such as high rigidity incomparable with any other, high precision, and high endurance.
The rotation precision of an air
bearing is designed to be 0.05µm maximum, much more
precise than ball bearings. Another factor that is
crucial in achieving high precision is that the reproducibility
be 0.01µm maximum and that this value can be maintained.
Canon’s air bearings use porous chokes
in their bearings, so even under normal factory supply-air
pressure (490 kpa), they are sufficiently rigid for
common use. Compared with bearings with orifice chokes
and selfformed chokes, the rigidity per unit area
is higher, the flow consumption is about ten times
(one digit) smaller, and the damping capacity is also
higher than that of bearings with other types of chokes.
