Abstract: An optical test apparatus comprises: a) a motor rotating a spindle which in turn rotates a workpiece such as a magnetic disk substrate; b) an upper test head comprising a laser for providing an upper laser beam to the upper surface of the workpiece, an upper lens for receiving light reflected from the upper surface, and an upper detector for generating a signal indicative of the received light; and c) a lower test head comprising a lower laser providing a laser beam to the lower surface of the workpiece, a lower lens for receiving light reflected from the lower surface and a lower detector for generating a signal indicative of the received light. The path of the lower laser beam is displaced from a radial direction of the workpiece so that the lower lens can be placed closer to the laser spot than if it was not displaced.

Abstract: A head for use in a drive includes a heating element capable of generating heat sufficient to cause the head to have a shape that is similar or identical to the shape that the head has when performing an operation (e.g. writing) on a recording medium in the drive. The heating element is activated when the operation is not being performed. Hence, a head generates the same amount (or similar amount) of heat and is therefore at the same temperature (also called “operating temperature”), regardless of whether or not an operation (such as writing) is being performed. Therefore, the head maintains a fixed shape or has a shape that varies minimally, within a predetermined range around the fixed shape, that in turn results in maintaining fly height (distance between the head and the recording medium). The heating element may be implemented to use loss mechanisms inherent in a write transducer, e.g. by providing a center tap to the write transducer.

Abstract: A method and apparatus for inspecting substrates in which a laser beam traces a path along the substrate surface. The laser beam is circularly polarized, e.g. by a quarter wave retarder. This permits inspecting the substrate with less sensitivity to scratch direction than if the laser beam were not circularly polarized.

Abstract: An optical test head comprises one or more detectors for providing output signals indicative of the condition of a workpiece surface. Data from these detectors are stored in one or more memories only when the data from the detectors satisfy one or more conditions (e.g. the data exceed than a particular threshold). The data are then passed from the one or more memories to an electrical circuit for processing. In addition, location information is stored in one or more memories and passed on to the electrical circuit when the data from the detectors satisfy the one or more conditions.

Abstract: An optical test head comprises one or more optical input paths by which a beam of light is communicated from a light source to a workpiece and one or more optical output paths by which light reflected off of the workpiece is communicated to a detector. The input optical path and the output optical path can include one or more mirrors and one or more lenses. At least one of the optical paths includes a layer for trapping and/or absorbing stray light. One or more of the lenses includes an anti-reflective coating for reducing noise caused by unwanted light reflection off of the lenses. The optical paths include one or more masks reducing stray light. The one or more masks can have an adjustable aperture (e.g. an iris).

Abstract: An optical test head comprises a block of material with a plurality of optical paths extending therethrough. At least one of the optical paths is an input optical path for receiving laser light and holding a lens for focusing the laser light on a workpiece that is proximate the head. At least another of the optical paths is an output path for receiving light that is reflected off of the workpiece and providing that light to a detector. (In one embodiment, several detectors are provided to direct specularly reflected light, narrow angle scattered light, wide angle scattered light and back scattered light to associated detectors.) Other optical elements can be affixed within or to the block of material. The test head can be used without requiring the individual optical elements to be aligned or adjusted.

Abstract: An optical test apparatus comprises a first: a) a motor that rotates a spindle which in turn rotates a workpiece such as a magnetic disk substrate; b) an upper test head comprising a laser for providing an upper laser beam to the upper surface of the workpiece, an upper lens for receiving light reflected from the upper surface, and an upper detector for generating an electrical signal indicative of the received light; and c) a lower test head comprising a lower laser providing a laser beam to the lower surface of the workpiece, a lower lens for receiving light reflected from the lower surface and a lower detector for generating an electrical signal indicative of the received light. The path of the lower laser beam is displaced from a radial direction of the workpiece in a manner that permits the lower lens to be placed closer to the laser spot than if the lower laser beam was not displaced.

Abstract: Apparatus for simultaneously optically inspecting top and bottom surfaces of a workpiece comprise upper and lower test heads, each head comprising at least one laser for providing a laser beam that scans its associated workpiece surface and at least one detector for detecting reflected laser light. The directions of the laser beams are selected so as to reduce or prevent cross-talk interference between the upper and lower test heads.

Abstract: An optical test head comprises a laser source for providing a laser beam. The laser beam passes through a cylindrical lens for modifying the shape of the beam and a spherical lens for concentrating the beam onto a workpiece (typically a magnetic disk platter). The cylindrical lens both a) elongates the laser beam along the radial direction of the platter (by reducing the effective numerical aperture in the radial direction); and b) causes the beam to be out of focus in the radial direction (although the beam is typically in focus in the circumferential direction). The size of the beam in the radial direction is substantially insensitive to the position of the cylindrical lens.

Abstract: A manufacturing cell for inspecting workpieces such as magnetic disk substrates comprises an input conveyor for providing workpieces to be tested, one or more testers for inspecting the workpieces, and three or more output receptacles for receiving tested workpieces. One or more robotic arms move the workpieces from the input conveyor to the tester and from the tester to one of the output receptacles depending upon the results of the test performed by the tester. The output receptacles include a pass receptacle, a reject receptacle, and at least an additional receptacle for workpieces that are to be re-worked or studied further. If the additional receptacle is full, workpieces that would otherwise be provided to the additional bin are placed in the reject receptacle. The reject receptacle is very large, so that it is rarely filled to capacity, and it is rarely necessary to shut down the manufacturing cell to replace the reject receptacle.

Abstract: A head for use in a drive includes a heating element capable of generating heat sufficient to cause the head to have a shape that is similar or identical to the shape that the head has when performing an operation (e.g. writing) on a recording medium in the drive. The heating element is activated when the operation is not being performed. Hence, a head generates the same amount (or similar amount) of heat and is therefore at the same temperature (also called “operating temperature”), regardless of whether or not an operation (such as writing) is being performed. Therefore, the head maintains a fixed shape or has a shape that varies minimally, within a predetermined range around the fixed shape, that in turn results in maintaining fly height (distance between the head and the recording medium). The heating element may be implemented to use loss mechanisms inherent in a write transducer, e.g. by providing a center tap to the write transducer.

Abstract: Apparatus for detecting defects in a substrate comprises a laser for providing a laser beam, and a bi-cell photodiode comprising two cells. Circuitry coupled to the bi-cell photodiode provides a signal equal to (L−R)/(L+R), where L and R equal the signal strengths of the signals provided by the left and right photodiode cells, respectively. The photodiode is biased so that it exhibits reduced capacitance, and can provide increased output signal bandwidth.

Abstract: Substrate inspection apparatus in accordance with the invention comprises optics for reflecting a laser beam off of a substrate and a detector for detecting the reflected laser beam. If a defect is present at the point where the laser reflects off the substrate, the laser will be deflected at an angle. Circuitry coupled to the detector generates a first signal that provides a measure of the extent to which the laser beam is deflected. (This signal is a measure of the slope of the defect walls.) An integrator receives that signal, and generates a second signal that is the integral of the first signal. The second signal is a measure of the height of the defect. The first and second signals provide a measure of the types of defects present on the substrate, and are used to determine whether the substrate is acceptable or should be rejected. In accordance with a second embodiment of the invention, laser beams are reflected off both the top and bottom surfaces of the substrate and detected by detectors.

Abstract: A method for texturing a glass ceramic substrate comprising the steps of applying a laser pulse to the substrate such that a portion of said substrate is heated to a temperature higher than the glass transition temperature of the glass phase of said substrate but lower than the melting point of the crystal phase of said substrate.

Abstract: Formation of laser texture features simultaneously on the target surfaces of each side of magnetic recording disk is facilitated by optical and mechanical components permitting excellent balance of optical power between each target surface, excellent matching of the radial position of laser texture features between each target surface, and excellent focusing of laser beams on each target surface. Polarization of the source laser beam may be used to controllably balance and direct a single source beam into individual beam paths for each target surface. Handling, automation complexity, and manufacturing time is thereby reduced.

Abstract: Reflection of a generated radiation beam (e.g., laser) from a disk substrate during radiation-induced texturing such that the reflection interferes with the generated radiation beam is eliminated as follows: the beam path of the laser beam is passed through focusing optics to focus the beam to a spot on the substrate surface; the beam path is offset from the center of the focusing optics so that the focusing optics bend the beam path, and further so that the beam is angled from normal to the surface of the disk, for example by between 2 and 5 degrees; and that portion of the beam reflected by the disk surface is blocked by appropriate means prior to its impinging upon the source of the generated radiation beam.