Abstract: An apparatus and method for efficient defect management in a magneto-optical data storage system store a map of current and predicted defective physical addresses of a recording disk, and then skips defective data wedges to more completely utilize the non-defective recording surface area available for a given track. The invention also stores groups of physical addresses that share defects to decrease the number of entries in the map of defective physical addresses, and also to increase the effective defect management capacity of existing hardware and software.

Abstract: A micro-motor position controller utilizes a ratiometric position sensor that operates independent of any reference voltage sources. A first capacitor and a second capacitor in a micro-motor are connected in series and form one section of a capacitive bridge. The other section of the bridge is ground. A first sinusoidal voltage is created at the top of the capacitive bridge and a second sinusoidal voltage that is 180 degrees out of phase from the first sinusoidal voltage is created at the bottom of the bridge. The motor is moved and the capacitance values of the first and second capacitors are changed until, ultimately, there is no voltage present on the armature of the motor. The voltage level present at the armature is measured relative to AC ground, and is used as an error signal to control the position of the motor.

Abstract: A system and method for encoding read-only information comprises a storage medium, a plurality of position marks disposed on the storage medium, and a light beam directed towards the position marks to produce a reflection of the light beam from the position marks. The position marks are configured such that the reflection of the light beam is not responsive to a plane of polarization of the light beam. In one embodiment, the position marks comprise rows of substantially circular pits. The dimensions of the substantially circular pits depend on a wavelength of the light beam and a numerical aperture of a lens that directs the light beam towards the position marks.

Abstract: Fabrication of an MO disc, the formation of a master pattern of servo and track information, and the subsequent transfer of that pattern to a series of pits and grooves on a substrate. On top of that substrate, at least one sacrificial layer is provided atop a relatively hard layer. The recording stack may be provided with both silicon nitride and silicon dioxide top layers, with the silicon dioxide layer acting as a sacrificial layer to ensure that the hard layer, of silicon nitride, remains at the end of the process. A layer of aluminum or aluminum alloy may be deposited, with the aluminum plugs filling the grooves and pits (created by the embossed servo information) to a level higher than any of the adjacent layers of silicon dioxide, silicon nitride, or similar dielectric layer.

Abstract: A method of writing servo information for hard disc drives, and disc drives built according to the method are disclosed. The method includes writing position reference information on a reference disc surface prior to mounting a disc assembly into a hard disc drive. Once the disc assembly is mounted in the disc drive, servo information is written onto the disc surfaces based upon the pre-written position reference information. Subsequently, the position reference information can be erased or written over by user data.

Abstract: A disc drive with an information portion previously written on a rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing a reference mark to the rotatable disc surface in substantial time alignment and phase and frequency coherent with the information portion previously written to the rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing the reference mark, a pulse detector circuit for creating logic level signals from the reference mark, a pattern generator for generating reference mark write signals from the logic level signals, a memory buffer for storing radial position correction tables and values for writing the reference mark, and a self-servo control and sequencing circuit synchronizing timing signals for writing the reference mark to rotatable disc surface of disc drive.

Abstract: A data storage system including a source of heat, a substrate, a storage layer, a lubricant layer, a flying head, and a dielectric layer is disclosed. The dielectric layer is disposed between the lubricant layer and the storage layer. The flying head is disposed above the lubricant layer. The dielectric layer has a heat capacity that is sufficient to generate a temperature gradient between the storage layer and the lubricant layer so as to reduce lubricant evaporation onto the flying head.

Abstract: A system and method are provided for processing signals in a magneto-optical computer memory device to detect mispositioning of a head with respect to a track centerline. A light beam is scanned over a first and a second set of radially offset optically-detectable position marks formed in the rotating medium surface. A detector receives the reflected light beam and responsively generates a position signal having a plurality of pulses corresponding to the position marks. The position signal is then passed through a differentiator circuit. The differentiated position signal may then be applied to low pass filter and resonator circuits, and is subsequently conveyed to a finite time integrator for rectification and detection of the areas of the pulses associated with the first and second set of position marks. Mispositioning of the head is detected by comparing the pulse areas of the first and second set of position marks.

Abstract: A system and method for encoding servo sector information in a nonvolatile data storage and retrieval system using rotating recording disks. Servo sectors are angularly-spaced approximately radial regions reserved for position reference and tracking adjustment information. Servo timing marks including means for detecting defects on the recording surface, encoded track address and sector address data, and position error signal blocks are permanently fabricated into a number of servo sectors. The present invention helps the storage system controller locate, certify, and follow any particular track and sector while maximizing the amount of disk surface area available for data storage and retrieval.

Abstract: A system and method to compensate for data defects within a magneto-optical computer memory device comprises a data channel coupled to the memory device for receiving and processing data signals, and a detector channel coupled to the data channel for detecting the data defects and then generating corresponding defect-skipping pulses. The data channel responsively uses the defect-skipping pulses to compensate for the data defects and thus maintain reliability of the data signals.

Abstract: A system and method is disclosed for correcting gain and offset errors in a signal amplifier for a position sensitive detector. The present invention eliminates the need to perform division for normalization by holding constant a signal proportional to the sum of the two signals generated by the position sensitive detector. First the two signals generated by the position sensitive detector are pulse-width modulated with a common variable duty cycle clock, and then the resulting modulated signals are low-pass filtered to extract the DC component. The duty cycle is varied so that the sum of the two DC components is held constant. In the preferred embodiment, the means for varying the duty cycle are closed-loop feedback and open-loop feed forward. The closed-loop feedback gives long term accuracy and the open-loop feed forward gives rapid settling time.

Abstract: The present invention proposes a new servo track writing technique called Extended Copying with Head Offset (“ECHO”). The read and write elements of the read/write head are offset from each other. A servo writer writes a guide pattern on the magnetic media disc. ZAP correction factors are added to the guide pattern. The head disc assembly is then connected to an electrical control system for self-propagating servo writing. The actuator arm is displaced until the read head is aligned over the guide pattern. A new servo track is written by the write element. ZAP correction factors are added to the newly written servo track. The actuator arm is displaced until the read element is aligned with the newly written servo track. A new servo track is written. ZAP correction factors are added to the newly written servo track. The process is repeated until a desired number of servo tracks are written.

Abstract: A magnetic medium comprises a magnetic disc having a read surface that has a plurality of tracks, at least some having servo sectors. The servo sectors comprise a plurality of magnetic irregularities, such as pits or regions of reduced magnetic coercivity, arranged in a servo pattern along the servo sector at a servo frequency. A magnetic pattern is recorded in the disc along the servo sector at a high carrier frequency. A process for manufacturing the servo pattern and for recovering servo data from the servo pattern are also described.

Abstract: Marks with curved edges are used in data patterns and sensed with proximity recording. Circular, elliptical, and oval marks are examples of marks with curved edges that can be used in the present invention. The marks with curved edges are used to define data patterns (e.g. position error signal patterns) as a function of radius. If the marks with curved edges have been recorded longitudinally, an amplitude of a read back signal, such as a peak amplitude, is determined in order to generate a position error signal. If the marks with curved edges have been recorded vertically, an area under the curve of the read back signal is determined in order to generate a position error signal.

Abstract: A method and system for monitoring in real-time changes in operating conditions such as temperature of a magnetic super resolution magneto-optical system which produce variations in aperture size in the media readout layer. The magnitude of a magneto-optical (MO) amplitude signal in a reflected laser beam is monitored, normalized by dividing by the laser power, compared to the amplitudes in a table of stored values, and used to derive a laser power feedback signal for controlling the power of the laser to maintain a predetermined aperture size. The MO amplitude signal is derived from patterns representing calibration tones prerecorded onto portions of the data tracks of the MSR media.

Abstract: A system and method for generating position error signals within a magneto-optical computer memory device whose track pitch is close to the full width half maximum width of the laser spot, the narrow track being typical of data stored on magnetic super resolution media. The magneto-optical computer memory device comprises a storage media for storing information, position marks embossed on the storage media, a head device coupled to the storage media for sensing the position marks to generate position error signals, and a correction device coupled to the head device to access the position error signals and responsively position the head device to correctly sense the stored information.

Abstract: Fabrication of an MO disc, the formation of a master pattern of servo and track information, and the subsequent transfer of that pattern to a series of pits and grooves on a substrate. On top of that substrate, at least one sacrificial layer is provided atop a relatively hard layer. The recording stack may be provided with both silicon nitride and silicon dioxide top layers, with the silicon dioxide layer acting as a sacrificial layer to ensure that the hard layer, of silicon nitride, remains at the end of the process. A layer of aluminum or aluminum alloy may be deposited, with the aluminum plugs filling the grooves and pits (created by the embossed servo information) to a level higher than any of the adjacent layers of silicon dioxide, silicon nitride, or similar dielectric layer.

Abstract: A system and method for efficient coupling between optical elements comprises a memory containing an alignment module configured to align a light beam with an optical element to maximize coupling efficiency, and a processor coupled to the memory to control the alignment module. A position sensitive device indirectly senses a position of the light beam on the optical element and sends the position to the processor. The alignment module directly measures coupling efficiency where the light beam contacts the optical element. The alignment module identifies a direction of increasing coupling efficiency and aligns the light beam with the optical element along that direction until maximum coupling efficiency is achieved.

Abstract: Curvilinear servo sector patterns are produced on a master media by determining a series of offsets between a radially aligned reference and the desired curvilinear servo sector and expressing each offset as a delay that can be expressed in settings for controlling a master writer. Incorporation of the delay into the master writer allows a curvilinear servo sector pattern to be produced using data mapping that is ordinarily used for the radially aligned servo sector pattern. Thus, curvilinear servo sector patterns with a desired resolution are produced without increasing computational overhead or memory requirements, or decreasing throughput. The delay can be converted into control settings such as sector delay, clock cycle delay and residual fractional delay settings that each represent a portion of the delay.

Abstract: A system and method for directly measuring the alignment error in a fiber-optic coupler is disclosed. In one embodiment, an optical switch utilizes a beam deflection mirror. When the beam deflection mirror directs an incident light beam to a particular fiber, the incident light beam may enter the fiber at a location offset from the center of the fiber. When the incident beam is reflected at the opposite end of the fiber, the beam returns and exits the fiber exactly at the center of the fiber. The difference between the entry and exit points results in a return beam path different than the incident beam path. This different return beam path may be used to impinge upon a quadrant detector, whose anode currents may then contain a direct measurement of the distance between the entry and exit points on the fiber.