Abstract: An optical recording system having a routing prism and an objective lens bonded together with a slider to form an integrated unit. A slider is attached to the end of an arm of a rotary actuator. Housed within the slider is a prism and an objective lens. The prism directs a laser beam downwards through the objective lens which focuses the laser beam onto the surface of an optical disk.

Abstract: A telecentric rotary actuary in an optical storage system. A laser generates a laser beam which is focused by an objective lens onto an optical disk in order to write data to and read data from the optical disk. In performing a seek, a galvo rotates a mirror in order to reflect the laser beam to different radial displacements in reference to the optical disk. The position of the laser beam is detected, and a rotary actuator, to which the objective lens is attached, follows the movement of the laser beam. A telecentric optical system comprising a relay lens and an image lens is used to minimize an offset between the laser beam and the objective lens. The relay lens focuses the laser beam to a back focal point. The image lens optically conjugates the back focal point to a front focal point corresponding to the objective lens in order to demagnify any offset.

Abstract: In an optical disk drive system, an apparatus and method for determining whether data read from a particular field within a particular sector of an optical disk corresponds to a code which specifies that the sector should not be erased. A crystal clock generates a synthesized clock signal. A front-end detector generates a signal synchronized to the synthesized clock signal which represents data read from the field. The signal is then serially shifted by a serial shift register. A comparator compares the shifted signal with the code specifying that the sector should not be erased. If there is a match, a counter is incremented. When the counter reaches or exceeds a pre-determined number, a signal is sent to the optical disk drive system indicating that the sector contains data which should not be erased.

Abstract: A small amplitude, low frequency, signal is added to the focus servo signal controlling the position of the objective lens of an optical disc storage system after focus acquisition has been achieved, so as to produce a slight defocusing effect of the light spot on the disc. The resulting variations in the read back signal is utilized by a synchronous detection circuit scheme to extract magnitude and polarity information of the focus offset present. That information is fed back to the focus servo signal to null out the focus offset, thereby assuring continual accurate focusing of the laser beam even under conditions of changes in the mechanical alignment of the optics of the storage system and/or the d.c. stability of the electronics of the storage system.