Abstract: An apparatus that can measure a space between a first surface and a second surface such as the air bearing between a slider and a disk. The apparatus may include a light source that can reflect a light beam from the slider and the disk. By way of example, the light beam can be reflected off of an Al2O3 cap of a slider. A birefringent element such as a Savart plate may split the reflected light beam into an ordinary beam and an extraordinary beam. The ordinary and extraordinary beams may combine to form an interference pattern that is detected by a photodetector. A controller receives data from the photodetector. The apparatus may have a mechanism which can vary a phase between the ordinary and extraordinary beams so that the controller can calculate a phase value &phgr;. The controller then computes the space from the phase value &phgr;. The variation in phase between the beams may be created by tilting the birefringent element, or moving the reflected light beam directed into the birefringent element.

Abstract: An apparatus that can measure a space between a first surface and a second surface. The apparatus may include a light source that can reflect a light beam from the first and second surfaces. A birefringent element may split the reflected light beam into an ordinary beam and an extraordinary beam. The ordinary and extraordinary beams are detected by a photodetector. The apparatus may include a controller that is coupled to the photodetector and which can compute the space from a phase value that is determined from data collected when the mechanism varies the phase between the ordinary and extraordinary beams, and a ratio between a first modulation amplitude detected from light reflected from the first and second surfaces and a second modulation amplitude detected from light reflected from the first surface when the second surface is not adjacent to the first surface. The ratio can also be used to compute the reflectance and index of refraction of the second surface.

Abstract: A loader that loads a head onto a disk. The head is typically mounted to a flexure arm which has a rail. The rail may have a top edge. The loader has a finger which can engage the flexure arm at a location that does not make contact with the top edge of the rail. With the present invention the finger can remain adjacent to the flexure arm even after the head is loaded onto the disk. There is no requirement to retract the finger after loading the head.

Abstract: An optical inspection station for inspecting a substrate. The substrate may include a first surface and a second surface. Light is reflected from both the first and second surfaces of the substrate. The light reflected from the first surface is detected by a light detector. A controller may determine a surface characteristic of the first surface from the detected light. The system may include a spatial filter that filters the light reflected from the second surface. The spatial filter eliminates the optical noise that may be created by the light reflected from the second surface.

Abstract: A method and apparatus for loading and unloading a slider onto the surface of a substrate. The present invention includes a suspension assembly that supports a slider having an air bearing surface. The suspension assembly is coupled to a guide rod that is biased toward a first, second and third bearing. The guide rod remains in continuous contact with at least two bearings. Movement of the slider toward or away from the substrate surface is accomplished by changing the position of one or more of the bearings. In this manner, a set of pivot points acting upon the guide rod is varied as the slider is rotated toward or away from the disk surface such that the axis of rotation of the slider varies as the slider is rotated toward or away from the substrate surface. The loader is also configured to minimize the lateral movement of the slider along the surface of the substrate as the slider is loaded or unloaded from the substrate surface.

Abstract: A self-acting air bearing for a pressurized spindle air bearing includes a bearing that is located within a cavity of a housing. The bearing and cavity may be shaped as a segment of a sphere. The spindle may be connected to a pressurized air source which creates an air bearing within a gap that separates the bearing from the housing. The bearing is attached to a shaft that is rotated by a motor. Rotation of the bearing creates a flow of air within the gap. The cavity and/or bearing may have a slot which cooperates with the air flow to increase the pressure of the air bearing.

Abstract: An apparatus and method for aligning an end effector that is attached to a robotic arm of a disk certification system. The end effector includes a disk paddle that is pivotally connected to an end effector housing. The end effector housing has a center opening that can receive a gripper subassembly. The disk paddle grabs a disk which has a center opening. The disk paddle is aligned by placing the end effector onto an alignment plate so that a center alignment pin of the plate is inserted into the center opening of the housing, and an outer alignment pin is inserted into the center opening of the disk. The end effector has an adjustment screw that can be adjusted to vary the position of the disk paddle so that the outer alignment pin is accurately positioned within the disk center opening. After alignment the end effector can be attached to the robotic arm.

Abstract: A positioner which can move an object such as a magnetic recording head. The positioner includes a housing with an inner opening. The housing is located within a coordinate system that includes an x axis, a y axis and a z axis. An electrical/mechanical transducer is coupled to the inner opening of the housing by at least two flexure joint inserts. Expansion or contraction of the transducer creates a movement of the housing along the x or y axis. The flexure joint inserts allow the transducer to be adjusted within the inner opening during assembly to minimize the out of plane movement of the housing along the z axis.

Abstract: The present invention is a clock head assembly that provides reference clock signals during servo writing of a magnetic disk in a hard drive. The clock head assembly includes a clock head that is pivotably mounted to a housing. The housing encloses a disk mounted to a spindle. The spindle is attached to the spindle motor of a hard disk drive through an opening in the housing. The spindle motor of the disk drive rotates the spindle and disk of the clock head assembly. The clock head is coupled to a cam that is manually actuated by a lever to move the clock head arm assembly between a loaded position and an unloaded position. During servo writing, the clock head is loaded onto the disk so that reference clock signals may be read from the disk and provided to a servo controller which utilizes the clock signals to write servo information onto the disk within the hard disk drive. Upon completion of servo writing, the clock head assembly is detached from the hard disk drive.

Abstract: An apparatus and method for aligning an end effector that is attached to a robotic arm of a disk certification system. The end effector includes a disk paddle that is pivotally connected to an end effector housing. The end effector housing has a center opening that can receive a gripper subassembly. The disk paddle grabs a disk which has a center opening. The disk paddle is aligned by placing the end effector onto an alignment plate so that a center alignment pin of the plate is inserted into the center opening of the housing, and an outer alignment pin is inserted into the center opening of the disk. The end effector has an adjustment screw that can be adjusted to vary the position of the disk paddle so that the outer alignment pin is accurately positioned within the disk center opening. After alignment the end effector can be attached to the robotic arm.

Abstract: A simple yet versatile noncontact optical inspection instrument and method are described for the inspection of magnetic disk surfaces for surface defects. This instrument is capable of inspecting the disk surface at any point in the disk manufacturing process. Surface defects such as bumps, pits and scratches can be measured. Surface contaminants such as particles and stains can also be measured. The instrument is also capable of discriminating between surface defects and surface contaminants. The instrument is comprised of two identical optical sensors which are located on opposite sides of the disk. A carriage supports and translates these sensors along the disk radius while a spindle rotates the disk. Both surfaces of the disk are therefore simultaneously scanned in a spiral fashion. The sensor's illumination optics produce a monochromatic focused spot of light which is normally incident upon the disk surface.

Abstract: A method of determining the distortion of an isolated pulse. Write data signals are recorded onto a magnetic storage media. Each write data signal includes a single transition that is relatively unaffected by adjacent transitions. Readback signals, each of which corresponds to a write data signal, are read from the magnetic storage media. The shape of the write data signals are measured. The difference between the shape of each write data signal and the shape of an ideal isolated pulse is measured.

Abstract: A rugged spindle for a disk certifier that test the disks of a hard disk drive. The spindle contains a first bearing and a second bearing that are coupled together by a shaft. The first bearing is coupled to a chuck that captures a disk. The second bearing is coupled to the spindle shaft of an electric motor which rotates the disk. The bearings each contain an outer graphite sheath that is separated from a hardened housing by an air bearing. The connecting shaft is bonded to the first and second bearings by an adhesive that is injected through longitudinal passages of the shaft. The bonding adhesive flows along the interface of the connecting shaft and bearings until the adhesive fills an indicator slot of the shaft. Air bearings are created during the bonding process of the second bearing to insure an accurate relationship between the two bearings and the housing.

Abstract: The present invention relates to an apparatus and method for amplifying a signal from a MR element of a hard disk drive magnetic recording head having a DC component and an AC component. The apparatus includes an amplifier circuit that amplifies the signal. An offset corrector circuit is coupled to the amplifier circuit and generates an offset signal representative of a complement of the dc component of the signal. A circuit is coupled to the amplifier circuit and the offset corrector circuit that combines the signal and the offset signal to provide an output signal representative of the AC component of the signal.

Abstract: A disk certifier which analyzes a read signal generated from a disk of a hard disk drive. The read signal typically has a sinusoidal waveform with modulated peak amplitudes. The waveform is generally defined by the equation A.multidot.sin(wt).multidot.(1-m(t)), where the term m(t) is the amplitude modulation of the signal. The peak signal is provided to a phase lock loop circuit which generates a multiplier peak signal generally of the form sin(wt). The certifier includes a multiplier which multiplies the read signal by the multiplier read signal to provide a multiplied read signal described by the equation A/2.multidot.(1-cos 2(wt)).multidot.(1-m(t)). The multiplied read signal is filtered by a low pass filter which has a cut-off frequency Wc below w. The low pass filter provides a filtered multiplied read signal which is described by the equation A.multidot.(1-g(t)), wherein the term g(t) is the portion of m(t) with frequencies below Wc.

Abstract: The present invention relates to a method and apparatus for the measurement of defects in magnetic recording disks using a logarithmic amplifier. A magnetic head senses a magnetic field of a magnetic disk and creates a read signal having a varying amplitude. The test apparatus has a squarer which receives and squares the read signal. A logarithmic amplifier coupled to the squarer converts the squared signal to a logarithmic signal. The logarithmic signal is filtered by a first filter. A second filter coupled to the logarithmic amplifier provides an average of the peaks of the logarithmic signal. A digital-to-analog converter coupled to the second filter scales the output of the second filter. The test apparatus further comprises a comparator having a first input and a second input, where the first input is coupled to the first filter, and the second input is coupled to the digital-to-analog converter.

Abstract: A test apparatus for testing a plurality of magnetic recording heads. The apparatus includes a tool which supports a bar that contains a number of individual magnetic recording heads. Alternatively, the tester may contain a tool which supports a plurality of individual sliders. The tool locates the heads within a magnetic field emanating from a coil wound magnet. The magnet has a length and permeability that provides a uniform magnetic field for each slider in the entire bar. The test apparatus includes a probe card that has a plurality of probe needles which make simultaneous contact with the bonding pads of each head. The needles are coupled to a test circuit that applies a constant current to the magnetic recording heads and measure a change in voltage as a function of a varying magnetic field. The tester can sequentially test the heads without spatially moving the bar, thereby minimizing the test cycle time of testing the heads. Alternatively, the tester may test two or more of the heads simultaneously.

Abstract: A non-contact optical method and apparatus for use in inspecting and measuring defects on a disk. The apparatus generates an interference pattern from a reference beam reflected from a surface of a transparent slider with a second beam reflected from a surface of a test disk. The resulting interference pattern is processed by a set of photodetectors and processing electronics to quantify and map the location and magnitude of asperities on the disk.

Abstract: A calibration medium that is used to calibrate a flying height tester which measures the gap of an air bearing formed between a magnetic recording head and a substrate. The medium contains a first ridge and a second ridge that extend from an underlying substrate. The ridges may be coated with a reflective material. A flying height tester can be calibrated by measuring light reflected from each ridge. The ridges have varying thicknesses so that the calibration medium will produce multiple data points.

Abstract: An efficient method and apparatus for taking the data needed for a glide test; the data includes measuring flying height of a slider over a regular rotating disk and measuring piezoelectric contact with the disk. An optical system provides a beam of light. To measure the flying height, part of the beam of light is reflected from a surface of the transparent slider. Another portion of the beam is reflected from the surface of a rotating disk. The two beams are transferred through an optical system and imaged onto a CCD camera which converts the separation of intensity maxima or intensity minima into information regarding the air gap separating the slider and the disk. A piezoelectric sensor on the slider measures slider contact with the disk. A processor combines data from the piezoelectric sensor with data from the CCD camera to measure disk asperities.