Abstract: This invention relates to a method of making optical fiber having low polarization dependence and an acousto-optical filter with low PDL. A section of the fiber is heated and then allowed to cool. At least the heating is controlled to reduce stresses in a cladding layer surrounding a core of the interaction length after the interaction length is allowed to cool to reduce polarization dependence of the cladding layer. Preferably, at least time and temperature of heating is controlled.

Abstract: A method for manufacturing a substrate for a magnetic disk comprises the acts of mounting a workpiece on a spindle; rotating the workpiece and scribing the workpiece to form first and second scribe lines on the top surface of the workpiece and first and second scribe lines on the bottom surface of the workpiece; and breaking the workpiece along the first and second scribe lines. The first scribe line on the top and bottom surface of the work piece defines the outer diameter of the substrate. The second scribe line on the top and bottom surface of the workpiece define the inner diameter of the substrate. Because scribe lines are formed on the top and bottom surfaces of the workpiece, the edge of the substrate is less jagged than substrates that are merely scribed on one side of the workpiece and then broken. Because the scribe lines are formed by mounting the workpiece on a spindle and rotating the substrate, the scribing can be done more precisely and quickly than scribe lines formed using an x-y platform.

Abstract: A method for manufacturing a magnetic disk comprises the step of applying a continuous laser beam to both sides of a glass workpiece and etching both sides of the workpiece with an aqueous acidic fluoride-containing etching solution. The portion of the workpiece receiving the laser beam etches at a much faster rate than the portions of the workpiece that were not exposed to the laser beam. The workpiece is then broken along a line or curve formed by the above-mentioned steps. The resulting structure is a substrate used to form a magnetic disk. The disk is completed by depositing an underlayer, a magnetic layer and a protective overcoat on the substrate.

Abstract: A method for marking the defective side of a magnetic disk comprises the step of applying a set of laser pulses to the defective side to form a mark that is visible to the naked eye. Thus, disk drive manufacturers can readily see whether one side of the disk is defective, and if so, which side of the disk is defective. Thus, the disk drive manufacturer can assemble a disk drive so as to use the functional side of the disk. The laser marks are formed on the disk without generating particulate contamination.

Abstract: This invention relates to a method of making optical fiber having low polarization dependence and an acousto-optical filter with low PDL. A section of the fiber is heated and then allowed to cool. At least the heating is controlled to reduce stresses in a cladding layer surrounding a core of the interaction length after the interaction length is allowed to cool to reduce polarization dependence of the cladding layer. Preferably, at least time and temperature of heating is controlled.

Abstract: A method for texturing a substrate comprises rotating the substrate while applying laser pulses thereto. Of importance, the rotational velocity of the substrate is varied during texturing to change the spacing of the resulting laser bumps in accordance with a periodic function. This helps reduce or eliminate vibration in a read-write head after the substrate is formed into a magnetic disk, and the magnetic disk is in use.

Abstract: A method in accordance with our invention for providing texture bumps on a substrate comprises the step of forming elliptical ridge-shaped bumps on the substrate. In one embodiment, substrate is used in the manufacture of a magnetic disk used in a disk drive. The elliptical bumps cause less vibration of the read-write head than circular bumps. The elliptical bumps also provide reduced friction between the disk and a read-write head during use.