Abstract: A disc holder for holding at least one media storage disc during rotation includes a central hub arranged for rotation about a central axis. The hub includes resilient centering arms which are arranged to provide an outwardly directed centering force on an internal bore of a carried disc in order to center the carried disc about the axis of rotation of the hub. The arms are disposed in, and movable in, planes which are substantially perpendicular to the axis of rotation of the hub. The disc holder may be arranged for carrying a stack of axially spaced media storage discs and may include axial gripping structure for holding the stack together. The gripping structure may include a central shaft which is held in position by ball shaped clamps which are spring loaded against inclined surfaces.

Abstract: A disc holder for holding at least one media storage disc during rotation includes a central hub arranged for rotation about a central axis. The hub includes resilient centering arms which are arranged to provide an outwardly directed centering force on an internal bore of a carried disc in order to center the carried disc about the axis of rotation of the hub. The arms are disposed in, and movable in, planes which are substantially perpendicular to the axis of rotation of the hub. The disc holder may be arranged for carrying a stack of axially spaced media storage discs and may include axial gripping structure for holding the stack together. The gripping structure may include a central shaft which is held in position by ball shaped clamps which are spring loaded against inclined surfaces.

Abstract: A disc holder for holding at least one media storage disc during rotation includes a central hub arranged for rotation about a central axis. The hub includes resilient centering arms which are arranged to provide an outwardly directed centering force on an internal bore of a carried disc in order to center the carried disc about the axis of rotation of the hub. The arms are disposed in, and movable in, planes which are substantially perpendicular to the axis of rotation of the hub. The disc holder may be arranged for carrying a stack of axially spaced media storage discs and may include axial gripping structure for holding the stack together. The gripping structure may include a central shaft which is held in position by ball shaped clamps which are spring loaded against inclined surfaces.

Abstract: A device and method for preparing media discs (2) in which servowriting and verification of the media may be carried out simultaneously. A common monolithic platform (1) is provided which supports air bearing systems which allow movement of a media disc rotary carrier (5), a servowriting headstack (3) and certifier headstack (4). Indirect drive may be provided to the rotary carrier (5) via coupling means (62).

Abstract: A collet for carrying a high-speed drill which comprises a collar (2) arranged to enclose a drill shank (1), an outer rim support (8) arranged for attachment to a drill, and a clamping mechanism between the collar and the outer rim support (8). The clamping mechanism is arranged to provide clamping forces between said outer rim support (8) and said collar so that said collar tightly grips a drill shank (1), as a consequence of centrifugal forces and of off center sprag effect forces.

Abstract: An air bearing comprising a static shaft having a circumferential surface in a form which when developed into a substantially flat plane takes the form of a series of shallow sinusoidal waves having at least three wave peaks, wherein one of the peaks carries a groove extending longitudinally parallel to the shaft axis and which bearing further comprises a hollow support member mounted for rotation around the static shaft.

Abstract: Rotating mirrors and methods for producing rotating mirrors with reduced variation in centrifugal distortion are disclosed. Pins (52) having a density different from that of the remainder of the body (51) of a rotating mirror are provided and located to reduce variation in centrifugal distortion when the mirror is rotated at high speed.

Abstract: An inclined mirror is provided in a cylindrical housing which has an open end and a closed end. An optical planar glass plate or window is mounted at the open end of the cylindrical housing. A laser beam enters the housing through the window and is reflected off the inclined mirror. The reflected beam leaves the housing through a side aperture in the housing. The cylindrical housing is rotated to scan the beam through a range of angles. Rotation of this optical system induces astigmatism in the beam due to the deformation of the inclined mirror at high rotational speed. If the window is tilted so that the entering laser beam is no longer normal to the window surface, then the window will induce a degree of astigmatism in the laser beam. The angular position of the window can be adjusted relative to the inclined mirror, thus compensating for the dynamic astigmatism due to rotation.

Abstract: A centrifugal spindle is described comprising a hollow shaft (1) having a collet (2) at one end for gripping a tool shank (12) and a centrifugal loading means (3) housed within the shaft (1). The loading means comprises two coaxial pistons (4,5) spaced from each other and linked by flexible connecting members (6) and intermediate bob weights (7). One piston (4) is secured axially to the hollow shaft (1) while the other piston is secured to the collet so that rotation of the shaft (1) causes the weights (7) to move radially outwards under centrifugal force to draw the piston (5) and collet (2) into the hollow shaft (1) gripping the tool shank (12). The collet may have spring loaded jaws forcing them into the closed position.