WO1997043079A1 - Shaped-beam laser texturing of magnetic media - Google Patents
Shaped-beam laser texturing of magnetic media Download PDFInfo
- Publication number
- WO1997043079A1 WO1997043079A1 PCT/US1997/008328 US9708328W WO9743079A1 WO 1997043079 A1 WO1997043079 A1 WO 1997043079A1 US 9708328 W US9708328 W US 9708328W WO 9743079 A1 WO9743079 A1 WO 9743079A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- texturing
- storage medium
- features
- magnetizable
- substrate
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/74—Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
- G11B5/82—Disk carriers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/0648—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising lenses
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/0652—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising prisms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/0665—Shaping the laser beam, e.g. by masks or multi-focusing by beam condensation on the workpiece, e.g. for focusing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/073—Shaping the laser spot
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/74—Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
Definitions
- the present invention relates to laser texturing of magnetic data storage media and more particularly to processes for controlling the shapes and orientations of texturing features formed in such texturing processes, as well as the resulting storage media.
- the laser beam also can be used to form a bump or nodule at each of the multiple locations.
- a dome or bump is surrounded by a ring.
- the individual topographical features are circular or axisymmetric, more particularly symmetrical about a vertical central axis in the case of features formed on a horizontal surface. While textures based on these features exhibit considerable improvement over mechanically formed textures, the ongoing quest for lower transducing head flying heights and shorter times for accessing data lead to more stringent tribological requirements.
- an object of the present invention to provide magnetic data storage media with transducer contact regions textured for improved wear and reduced dynamic friction. Another object is to provide a process for using a laser to texture the surfaces of magnetic data storage media, with more control over the shape and orientation and texturing features formed by the laser to impart a desired roughness. A further object is to provide a laser texturing process that affords more consistency in forming asymmetrical features such as rims and nodules on textured magnetic media.
- Yet another object is to provide magnetic media in which the orientation of non-circular, non-axisymmetric topographical features is determined with reference to the direction of transducing head accelerations and decelerations, to increase the performance benefits derived from the asymmetries.
- a process for surface texturing a magnetic data storage medium including the following steps: a. directing a coherent energy beam from a source thereof toward a magnetic data storage medium; b. locating beam shaping optics between the source and the storage medium, thereby shaping the beam to provide a shaped beam segment along which sections taken through the beam perpendicular to beam propagation have a selected non-circular sectional shape; and c. causing the coherent energy beam to impinge upon a selected surface of the storage medium at a plurality of locations thereon, altering the topography of the selected surface at each of the locations by forming a non-circular texturing feature, while orienting the features with major axes thereof substantially aligned in a predetermined direction.
- features formed according to this process are of the same general types as previously mentioned forms, including nodules, bumps and rims, having a smooth, rounded or rotund character that leads to reduced friction and increased wear.
- features formed by the present process are non- circular or non-axisymmetric in the sense of being substantially elongated in a direction parallel to the major plane of the data storage medium.
- the nodules or bumps are oblong or oval
- the rims are elliptical rather than circular.
- each feature has a major or "long" axis in the direction of elongation and a minor or short axis that is perpendicular to the major axis.
- the aspect ratio i.e. the major axis/minor axis ratio, can be in the range of about l.1 to about 10, and more preferably is in the range of about 2-6.
- elongated features provide several advantages. As the flying head approaches the texturing features, air flow resistance is reduced, due to the streamlined shape of the texturing features. Also, the more gradual increases in feature height result in the head experiencing less turbulence, allowing it to fly closer to the disk surface, and with the air bearing providing more stable support.
- One of these, specific to rim-like features is a reduced tendency to entrap material.
- the elongated, elliptical rims exhibit a height gradient in the direction of the major axis, from a maximum height along medial regions intersected by the minor axis, to minimal heights at opposite end regions intersected by the major axis.
- each nodule, rim or other feature has a height profile that varies, from a maximum height gradient or steepest profile in the vertical plane containing the minor axis, to a minimum height gradient or most gradual profile in the plane containing the major axis.
- Other planes yield intermediate gradients and profiles, with the maximum or minor-axis profile most like that of a similarly sized but axisymmetric feature.
- the beam shaping optics can take a variety of forms, the most simple being a single wedged prism, with a pair of cylindrical lenses being more suitable.
- the most preferred version of beam shaping optics comprises a pair of complementary wedged prisms.
- the wedged prisms are preferred due to their plane surface refraction of the coherent energy beam, which preserves beam collimation and propagation factor M 2 while minimizing aberrations and distortions. This enables a smaller focal spot size, suitable for forming smaller texturing features, while also enhancing control over the shape of the features.
- using beam shaping optics to provide a specially shaped, non-circular (in section) laser beam affords effective control over the shape and orientation of elongated texturing features, and affords a high degree of flexibility in terms of selecting aspect ratios. This is in contrast to tilting the laser beam, a possibility mentioned in the foregoing Ranjan patents and Meyer international publication, for which an aspect ratio as low as 2 would require a severe tilt of 60 degrees from the preferred orientation perpendicular to the treated surface.
- the improved control and flexibility afforded by optically shaping the laser beam allow a customizing of texturing heretofore unavailable, not only in selecting the degree of elongation, but in the consistency with which features conform to the desired asymmetry.
- Figure 1 is a plan view of a magnetic data storage disk and a data transducing head supported for generally radial movement relative to the disk;
- Figure 2 is an enlarged partial sectional view of the magnetic disk in Figure 1;
- Figure 3 is an elevational view of a texturing device for forming texturing features on the disk
- Figures 4A-4D illustrate energy distributions and profiles of a cylindrical laser beam and a shaped laser beam, respectively;
- Figure 5 is a perspective view of one of the texturing features, namely an elliptical rim
- Figure 6 is a top view showing an elliptical rim
- Figure 7 is a sectional view taken along the vertical plane containing a minor axis of the rim
- Figure 8 is a sectional view taken along the vertical plane containing a major axis of the rim
- Figure 9 is a perspective view showing an oblong nodule
- Figure 10 is a top view of the elliptical nodule
- Figure 11 is a sectional view taken along the vertical plane containing a minor axis of the nodule
- Figure 12 is a sectional view taken along the vertical plane containing a major plane of the nodule
- Figure 13 is an enlarged partial top view of the disk showing a pattern of topographical features formed on the disk;
- Figure 14 is a chart illustrating comparative dynamic friction due to axi ⁇ ymmetric texturing features versus non-axisymmetric texturing features
- Figure 15 illustrates an alternative pattern of texturing features
- Figure 16 illustrates an alternative texturing device
- Figure 17 illustrates a further alternative laser texturing device
- Figure 18 illustrates a further alternative asymmetric texturing feature
- Figure 19 illustrates yet another alternative asymmetric texturing feature
- Figure 20 illustrates a side profile of the feature in Figure 19.
- FIG. 1 and 2 a medium for recording and reading magnetic data, in particular magnetic disk 16 rotatable about a vertical axis and having a substantially planar and horizontal upper surface 18.
- a rotary actuator (not shown) carries a transducing head support arm 20 in cantilevered fashion.
- a magnetic data transducing head 22 is mounted to the free end of the support arm, through a suspension
- the rotary actuator and the support arm pivot to move head 22 in an arcuate path, generally radially with respect to the disk.
- a disk drive spindle 26 used to rotate the disk.
- upper surface 18 is divided into three annular regions or zones: a radially inward region 30 used for clamping the disk to the spindle; a dedicated transducing head contact zone 32; and a data storage zone 34 that serves as the area for recording and reading the magnetic data.
- head 22 When disk 16 is at rest, or rotating at a speed substantially below the normal operating range, head 22 contacts upper surface 18. When the disk rotates within the normal operating range, an air bearing or cushion is formed by air flowing between head 22 and upper surface 18 in the direction of disk rotation. The air bearing supports the head in parallel, spaced apart relation to the upper surface. Typically the distance between a planar bottom surface 36 of head 22 and upper surface 18, known as the head “flying height", is about 10 microinches (254 nm) or less. The flying height should be as low as practicable for maximum data storage density.
- rotation of the disk and pivoting of the support arm are controlled in concert to selectively position transducing head 22 near desired locations within data zone 34.
- the disk is decelerated and support arm 20 is moved radially inward toward contact zone 32.
- the disk 16 decelerates sufficiently to allow head 22 to engage the upper surface, the head is positioned over the contact zone.
- head contact with other regions of the disk surface is avoided.
- the disk is accelerated from stop, initially with head 22 engaged with disk 16 within the contact zone.
- Support arm 20 is not pivoted until the head is supported by an air bearing, free of the contact zone.
- Magnetic disk 16 is formed first by polishing, grinding or otherwise mechanically finishing an aluminum substrate disk 38 to provide a substantially flat upper surface.
- a nickel-phosphorous alloy is plated onto the upper surface of the substrate disk, to provide a non-magnetizable layer 40 with a uniform thickness within the range of about 2-12 microns.
- the upper surface of the Ni-P alloy layer i.e. a substrate surface 42, is polished to a roughness of generally less than about 0.1 microinch (2.54 nm) .
- a saturated cloth, paper or pad coated or flooded with cerium oxide, silicon carbide or another suitable grit, is used for this purpose.
- a liquid slurry containing grit also may be used.
- substrate disks can be obtained with Ni-P alloy layers already applied, then polished as described. After mechanical polishing, substrate disk 38 is laser textured at least within contact zone 32 to provide a desired surface roughness.
- Laser texturing involves melting the substrate disk at and near surface 42 at multiple locations, forming at each location a texturing feature, as will be described in greater detail below. The texture is influenced by the general pattern of texturing features, as well as the size and shape of the features individually.
- Fabrication of disk 16 after texturing involves the application of several layers.
- Chrome is sputter deposited onto substrate surface 42, preferably to a thickness in the range of about 10-100 nm, to form an underlayer 44.
- the underlayer is well suited for subsequent deposition of a magnetic thin film, in that the crystalline structure of underlayer 44 can control the epitaxy of the crystalline magnetic film.
- the magnetic thin film provides a recording layer 46 for storing the magnetic data.
- the thin film material preferably is a cobalt/tantalum/chromium alloy or a cobalt/platinum/chromium alloy, and is sputter deposited to a thickness in the range of about 10-50 nm.
- a protective layer 48 typically carbon, is sputter deposited onto the recording layer to a thickness of about 5-30 nm.
- Underlayer 44, recording layer 46 and cover layer 48 are substantially uniform in thickness. Consequently, upper surface 18 substantially replicates the texture of substrate surface 42.
- Laser texturing preferably is accomplished with a laser texturing device 50.
- device 50 includes a spindle 52 for rotatably supporting substrate disk 38.
- a carriage 54 supports a laser module 56 for reciprocal movement radially with respect to the disk.
- the laser module includes a naodymium: yetrium lithium fluoride (Nd:YLF) diode laser 58, and beam expanding collimating optics 60 for collimating the diode laser output to produce a beam 62 in the form of a circular cylinder having a diameter of about 1-10 mm.
- the preferred diameter varies with the application and the other optional components involved.
- the beam has a Gaussian energy distribution as indicated in Figure 4A. Sections of the beam perpendicular to propagation, i.e. horizontal sections as viewed in Figure 3, exhibit circular profiles as shown in Figure 4B.
- the laser module also includes several optical components for selectively shaping beam 62, to expand the beam in a first direction while leaving the beam substantially unchanged in another direction perpendicular to the first. These components include a pair of wedged prisms 64 and 66 spaced from one another along the beam path. The prisms are supported by adjustment components, schematically illustrated at 68 and 70 respectively, that permit azimuth angle adjustment of each prism about an axis perpendicular to the plane of the drawing.
- the beam having been twice refracted and twice enlarged in the same direction, emerges from prism 66 as a shaped beam segment 82.
- Sections of shaped beam segment 82 perpendicular to propagation have elliptical profiles as indicated in Figure 4C.
- the circular profile in Figure 4B illustrates the circular or axisymmetric nature of beam 62 upstream of the beam shaping optics.
- the beam diameter is constant, regardless of the angle at which it is taken.
- non-circular, non- axisymmetric shaped beam segment 82 exhibits the elliptical profile of Figure 4C, with axes ranging from a minor axis "a” taken in the horizontal direction and normal to the plane of Figure 3, to a major or long axis "b” taken in the horizontal direction parallel to the plane of Figure 3.
- the energy distribution in beam segment 82 remains Gaussian, but like the beam itself is broadened in the direction parallel to the major axis, as shown in Figure 4D.
- Prisms 64 and 66 can be considered complementary in the sense that (1) they have the same size, shape and refractive index and thus refract incident coherent energy by the same amount or same angle; and (2) they are positioned to refract energy in opposite directions, so that shaped beam segment 82 is parallel to beam 62 upstream of the shaping components.
- This feature while not essential is advantageous because it most effectively preserves the beam collimation and propagation factor M 2 .
- the propagation factor M 2 describes the purity of the TEM 00 mode. For a perfect Gaussian beam, M 2 is equal to
- Azimuth angles of prisms 64 and 66 can be adjusted through components 68 and 70 to change the angles of incidence ⁇ , and thus change the aspect ratio b/a of the shaped beam segment. Through this adjustment to the prisms it has been found practicable to increase the aspect ratio from 1 (circular profile) up to about 6.
- the aspect ratio of shaped beam segment 82, due to the wedged prisms can be determined by the equation:
- b _ cps[arcsin(sin g/n) ] a b cos ⁇ where ot is the angle of incidence and n is the index of refraction (both prisms) .
- a focusing lens 84 converges the beam and defines a focal spot or area 86 of beam impingement onto substrate surface 42.
- Focal spot 86 has the elliptical shape and aspect ratio of the beam section shown in Figure 4C.
- focal spot 86 is controlled by prisms 64 and 66 and more specifically their azimuth angles, while the size of the focal spot is controlled by focusing lens 84 in conjunction with the prisms, and of course in part by collimating optics 60.
- focusing lens 84 in conjunction with the prisms, and of course in part by collimating optics 60.
- the focusing of laser energy onto the metallic surface of the substrate disk causes highly localized melting at the surface. Although the material resolidifies rapidly, there is sufficient material flow to form either a rim or a nodule, with higher energy levels tending to result in rims rather than nodules.
- Figure 5 shows in perspective a texturing feature formed using device 50, namely a rim 88.
- Figures 6-8 illustrate the rim profile from the top and from two vertical sections through the rim perpendicular to one another.
- rim 88 is elongated or elliptical, having an aspect ratio b/a of greater than one. This aspect ratio is not necessarily proportional to the aspect ratio of the beam and focal spot. However, there is a correspondence, in that within practical limits, the aspect ratio of rim 88 tends to increase with increases in the beam and focal spot aspect ratio.
- rim lengths are within the range of about 6 to about 50 microns (more preferably 10-20 microns) , with rim widths (minor axis a) in the range of about 3-10 microns (more preferably 4-8 microns) .
- the rim aspect ratio should be at least about 1.1, and at most about 10. More preferably, the aspect ratio ranges from about 2 to about 6.
- rim 88 and its adjacent portion of substrate disk 38 are shown in section along the vertical plane containing minor axis a.
- the profile in that plane is substantially the same as the profile resulting from a vertical plane taken through a circular or axisymmetric rim of the same height.
- a top edge 90 of the rim is curved, illustrating a key difference from circular rims in that the rim height is non-uniform.
- the sectional view in Figure 8 is along the vertical plane containing major axis b.
- opposite portions of the rim are farther apart from one another, and the rim sections themselves have more gradual height gradients.
- Rim top edge 90 is highest along medial regions 92 of the rim, i.e. regions intersected by the minor axis.
- the rim top edge slopes downward in both directions toward opposite ends 94 and 96 of the rim, i.e. regions intersected by the major axis, where the height is at its minimum.
- all features have more gradual inclines.
- a nodule or bump 98 formed by device 50 is shown in perspective in Figure 9, with corresponding top, end sectional and side sectional views in Figures 10-12.
- the sectional views are based on vertical planes through the a and b axes with the profile in Figure 11 comparable to a profile of a circular bump having the same height, and the profile view in Figure 12 showing a substantially more gradual incline from a maximum height at the center of bump 98.
- Maximum heights for features like rim 88 are typically in the range of 5-30 nm, and maximum nodule or bump heights also typically are in the range of 5-30 nm. More preferably, the maximum heights range from 10-20 nm.
- device 50 is used to provide a desired pattern or distribution of the texturing features throughout contact zone 32.
- One suitable pattern is a spiral, formed by rotating substrate disk 38 on a vertical axis at an angular speed ⁇ ( Figure 3) while at the same time moving the laser module radially with respect to the disk.
- the laser is pulsed to form individual texturing features, either rims or nodules, for example at a frequency in the range of 10,000-100,000 pulses per second.
- the substrate disk is rotated to provide a suitable linear velocity, for example about one meter per second.
- the disk moves continually during texturing, but for purposes of individual feature formation can be considered stationary due to the extremely short duration of each pulse, e.g. about 70 ns.
- rims 88 can be seen in Figure 13, showing a segment of contact zone 32.
- Each rim 88 is aligned with its minor axis "a” in the radial direction (with respect to the substrate disk) , and with its major axis "b" in the circumferential direction.
- This alignment or orientation is specifically chosen with reference to the movement of head 22 and disk 16 relative to one another, particularly during accelerations and decelerations of the head. (although accelerations and decelerations actually are due to disk rotation, they are commonly discussed in terms of circular travel of the transducing head relative to the disk.)
- the orientation of rims 88 with their major axes in the circumferential direction has been found highly favorable, because it positions the most gradual rim height gradients in the direction of head travel. This reduces turbulence, reduces stiction and dynamic friction, and permits the head to have a lower flying height above the disk.
- the chart in Figure 14 shows the reduced dynamic friction.
- a plot 100 based on disk 16 shows a dynamic friction coefficient of approximately 0.6.
- a comparative plot 102 based on circular or axisymmetric texturing features, exhibits a substantially higher dynamic friction above 0.8 over most of the 20,000 ccs (controlled start stop) cycle range.
- Figure 15 shows an alternative pattern in which the location between consecutive features 104 is substantially reduced. Adjacent rims are connected to one another at their ends, thus to form a substantially continuous spiral track.
- texturing features can be formed in concentric rings rather than spiral, or even distributed somewhat randomly throughout the contact zone, so long as they are aligned with their major axes in the circumferential direction.
- Another improvement is the reduction in noise or acoustic energy at transducing head takeoff and landing.
- the acoustic energy has been found to be about 100 mV.
- the acoustic energy is substantially higher, e.g. about 200 mV.
- magnetic disks with landing zones laser textured with elliptical features in end-to-end contact as shown in Figure 15 exhibit acoustic energy of abut 70 mV at takeoff and landing, a substantial reduction compared to previous laser texturing, and a favorable comparison to mechanical texturing. This significant reduction most likely is due to the more gradual texturing feature height gradients in the direction of head travel, and is likely to allow lower transducing head flying heights over the contact.
- Figure 16 illustrates and alternative device 105 for forming the texturing features, including a spindle 106 rotatably supporting a substrate 108, a carriage 110 and a laser module 112 moved by the carriage radially of the spindle and substrate.
- Laser module 112 includes a laser 114 and collimating optics, a single wedged prism 116 for shaping the laser beam 118, and a focusing lens 120. While wedged prism 116 is suitable for expanding the beam in one direction while leaving its direction constant in the other, there is less flexibility in terms of adjusting aspect ratios, since each angular adjustment of prism 116 (e.g. to change the angle of refraction) also changes the direction of the shaped beam exiting the prism.
- Figure 17 illustrates a further alternative laser texturing device 122, similar to device 50 with the exception that the beam shaping optics include cylindrical lenses 124 and 126 in lieu of the wedged prisms.
- Downstream lens 126 has a larger radius of curvature than the upstream lens.
- the two lenses are centered on a common axis, so that a shaped beam segment 128 not only is parallel to incident beam 130, but also coaxial. While this can be considered an advantage, in most respects device 50 is preferred, due to the need for and difficulty in achieving perfect alignment of the cylindrical lenses in terms of their centers, distance from one another and orientation.
- lenses 124 and 126 are subject to spherical aberration coma, astigmatism, field curvature, and distortion.
- Figure 18 illustrates an alternative rim-like feature 132 formed for example using device 50.
- the feature height at the opposite ends of the ellipse can be made negligible, in effect forming two opposite end gaps 134 and 136, or in other words forming two elongate generally crescent-like ridge sections confronting one another, as indicated at 138 and 140 in Figure 18.
- features 132 provide the same advantages as rims 88 discussed above, with a further advantage in that features 132 are open and considerably less prone to debris entrapment. The reduced tendency to entrap material is likely to enhance wear characteristics.
- Figure 19 illustrates a further alternative texturing feature 142 in the form of an irregular rim.
- feature 142 has a further asymmetry, in that the maximum height regions 144 are offset from the minor axis rather than centered.
- Figure 20 illustrates the rim side profile 146. Beneath the profile, an arrow 148 indicates the circumferential direction of disk rotation, i.e. the opposite to the direction of transducing head "travel". The side profile exhibits a relatively steep slope 150 and a more gradual slope 152. As before, the major axis of the feature coincides with the circumferential direction. When the disk rotates in the direction shown, the head first encounters the more gradual slope 152.
- the benefits achieved by elongating and properly aligning the texturing features are increased by forming an irregular elongated feature, oriented with reference to head and disk movement as shown.
- magnetic data storage disks can be textured, particularly throughout dedicated head contact areas, for more controlled accelerations and decelerations of the head, reduced dynamic friction, and improved resistance to wear.
- These advantages arise due to a process that affords more control over the shape and orientation of elongated, elliptical or otherwise non-axisymmetric texturing features.
- a high degree of consistency is achieved in forming and aligning asymmetrical features.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/849,001 US6225595B1 (en) | 1996-05-13 | 1997-05-13 | Shaped-beam laser texturing of magnetic media |
JP9541145A JPH11509483A (en) | 1996-05-13 | 1997-05-13 | Texturing of magnetic media with shaped beam laser |
DE19780476T DE19780476T1 (en) | 1996-05-13 | 1997-05-13 | Shape beam laser texturing of magnetic media |
GB9800584A GB2317359B (en) | 1996-05-13 | 1997-05-13 | Shaped-beam laser texturing of magnetic media |
HK98110974A HK1010166A1 (en) | 1996-05-13 | 1998-09-25 | Shaped-beam laser texturing of magnetic media |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US1726796P | 1996-05-13 | 1996-05-13 | |
US4234197P | 1997-03-17 | 1997-03-17 | |
US60/042,341 | 1997-03-17 | ||
US60/017,267 | 1997-03-17 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997043079A1 true WO1997043079A1 (en) | 1997-11-20 |
Family
ID=26689663
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1997/008328 WO1997043079A1 (en) | 1996-05-13 | 1997-05-13 | Shaped-beam laser texturing of magnetic media |
Country Status (7)
Country | Link |
---|---|
US (2) | US6225595B1 (en) |
JP (1) | JPH11509483A (en) |
KR (1) | KR19990028932A (en) |
DE (1) | DE19780476T1 (en) |
GB (1) | GB2317359B (en) |
HK (1) | HK1010166A1 (en) |
WO (1) | WO1997043079A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1999028905A1 (en) * | 1997-12-03 | 1999-06-10 | Quantum Corporation | Randomly laser-textured magnetic recording media |
SG84510A1 (en) * | 1998-03-14 | 2001-11-20 | Inst Data Storage | An apparatus and method for laser texturing a magnetic recording disk and a disk produced thereby |
EP1237034A2 (en) * | 2001-02-23 | 2002-09-04 | 3D Systems, Inc. | Optical system with electronic spot size control and focus control optics |
US6663938B1 (en) | 1997-12-12 | 2003-12-16 | Seagate Technology Llc | Media contact zone with bell-shaped texturing features |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6639177B2 (en) * | 2001-03-29 | 2003-10-28 | Gsi Lumonics Corporation | Method and system for processing one or more microstructures of a multi-material device |
US20030044647A1 (en) * | 2001-09-05 | 2003-03-06 | Iraj Kavosh | Laser textured magnetic disk |
US6951995B2 (en) | 2002-03-27 | 2005-10-04 | Gsi Lumonics Corp. | Method and system for high-speed, precise micromachining an array of devices |
JP4143607B2 (en) * | 2002-12-03 | 2008-09-03 | 富士通株式会社 | Laser irradiation apparatus for bending and laser irradiation method |
US20040265646A1 (en) * | 2003-06-27 | 2004-12-30 | Hitachi Global Storage Technologies Netherlands B.V. | Laser textured magnetic disk |
US20060256688A1 (en) * | 2005-05-11 | 2006-11-16 | Van Brocklin Andrew L | Methods and apparatus for shaping mark recorded on media with electromagnetic radiation beam |
US7576765B2 (en) * | 2005-05-11 | 2009-08-18 | Hewlett-Packard Development Company, L.P. | Methods and apparatus for detecting and optimizing laser mark quality on recording media |
US7729216B2 (en) * | 2005-07-05 | 2010-06-01 | Hewlett-Packard Development Company, L.P. | Methods and apparatus for marking media with collimated electromagnetic radiation beam |
BRPI0613034A8 (en) * | 2005-07-14 | 2018-01-02 | Lipothera Inc | injectable formulation for fat tissue accumulation, injectable formulation and method for treating fat accumulation, and method for reducing fat tissue. |
EP1921616A1 (en) * | 2006-11-09 | 2008-05-14 | Thomson Holding Germany GmbH & Co. OHG | Beam shifting element for an optical storage system |
JP5294916B2 (en) * | 2009-02-17 | 2013-09-18 | パナソニック株式会社 | Laser soldering equipment |
US8742288B2 (en) * | 2011-06-15 | 2014-06-03 | Asm Technology Singapore Pte Ltd | Laser apparatus for singulation, and a method of singulation |
KR20160093593A (en) * | 2013-12-05 | 2016-08-08 | 일렉트로 싸이언티픽 인더스트리이즈 인코포레이티드 | Method and apparatus for internally marking a substrate having a rough surface |
EP3708289A1 (en) * | 2019-03-11 | 2020-09-16 | FRONIUS INTERNATIONAL GmbH | Beamforming and deflection lens for a laser processing device and method for machining a workpiece by means of a laser beam |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3941973A (en) * | 1974-06-26 | 1976-03-02 | Raytheon Company | Laser material removal apparatus |
US4069080A (en) * | 1976-06-11 | 1978-01-17 | W. R. Grace & Co. | Method and apparatus of bonding superposed sheets of polymeric material in a linear weld |
US5062021A (en) * | 1990-03-12 | 1991-10-29 | Magnetic Peripherals Inc. | Selectively textured magnetic recording media |
US5388020A (en) * | 1991-10-23 | 1995-02-07 | Hitachi, Ltd. | Magnetic disk having improved surface configuration and magnetic disk unit including same |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1463493A (en) * | 1973-02-22 | 1977-02-02 | Bisgaard H F | Process controls |
US4948233A (en) * | 1984-02-20 | 1990-08-14 | Asahi Kogaku Kogyo Kabushiki Kaisha | Beam shaping optical system |
US5118577A (en) | 1988-03-10 | 1992-06-02 | Magnetic Peripherals Inc. | Plasma treatment for ceramic materials |
US4863809A (en) | 1988-03-10 | 1989-09-05 | Magnetic Peripherals, Inc. | Surface treatment for sliders and carbon coated magnetic media |
US5108781A (en) | 1990-03-12 | 1992-04-28 | Magnetic Peripherals Inc. | Process for manufacturing selectively textured magnetic recording media |
KR960005459A (en) * | 1994-07-04 | 1996-02-23 | 미우라 아끼라 | Magnetic recording medium, manufacturing method thereof, and recording and reading method |
US5528922A (en) * | 1994-12-27 | 1996-06-25 | International Business Machines Corporation | Method of making disk bumps with laser pulses for calibrating PZT sliders |
US5815346A (en) * | 1995-06-12 | 1998-09-29 | Maxtor Corporation | Textured slider surface |
US5759419A (en) * | 1995-10-05 | 1998-06-02 | Mitsubishi Chemical Corporation | Method of manufacturing a magnetic recording medium and a semiconductor laser texturing apparatus |
US5976714A (en) * | 1995-10-23 | 1999-11-02 | Mitsubishi Chemical Corporation | Magnetic recording medium and method of producing the same |
-
1997
- 1997-05-13 DE DE19780476T patent/DE19780476T1/en not_active Withdrawn
- 1997-05-13 JP JP9541145A patent/JPH11509483A/en not_active Ceased
- 1997-05-13 WO PCT/US1997/008328 patent/WO1997043079A1/en not_active Application Discontinuation
- 1997-05-13 KR KR1019980700234A patent/KR19990028932A/en not_active Application Discontinuation
- 1997-05-13 US US08/849,001 patent/US6225595B1/en not_active Expired - Lifetime
- 1997-05-13 GB GB9800584A patent/GB2317359B/en not_active Expired - Fee Related
-
1998
- 1998-09-25 HK HK98110974A patent/HK1010166A1/en not_active IP Right Cessation
-
2001
- 2001-03-06 US US09/799,840 patent/US6483666B2/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3941973A (en) * | 1974-06-26 | 1976-03-02 | Raytheon Company | Laser material removal apparatus |
US4069080A (en) * | 1976-06-11 | 1978-01-17 | W. R. Grace & Co. | Method and apparatus of bonding superposed sheets of polymeric material in a linear weld |
US5062021A (en) * | 1990-03-12 | 1991-10-29 | Magnetic Peripherals Inc. | Selectively textured magnetic recording media |
US5388020A (en) * | 1991-10-23 | 1995-02-07 | Hitachi, Ltd. | Magnetic disk having improved surface configuration and magnetic disk unit including same |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1999028905A1 (en) * | 1997-12-03 | 1999-06-10 | Quantum Corporation | Randomly laser-textured magnetic recording media |
US6663938B1 (en) | 1997-12-12 | 2003-12-16 | Seagate Technology Llc | Media contact zone with bell-shaped texturing features |
SG84510A1 (en) * | 1998-03-14 | 2001-11-20 | Inst Data Storage | An apparatus and method for laser texturing a magnetic recording disk and a disk produced thereby |
EP1237034A2 (en) * | 2001-02-23 | 2002-09-04 | 3D Systems, Inc. | Optical system with electronic spot size control and focus control optics |
EP1237034A3 (en) * | 2001-02-23 | 2002-10-16 | 3D Systems, Inc. | Optical system with electronic spot size control and focus control optics |
Also Published As
Publication number | Publication date |
---|---|
US6225595B1 (en) | 2001-05-01 |
HK1010166A1 (en) | 1999-06-17 |
DE19780476T1 (en) | 1998-10-15 |
GB2317359B (en) | 1999-06-09 |
US20010028535A1 (en) | 2001-10-11 |
KR19990028932A (en) | 1999-04-15 |
US6483666B2 (en) | 2002-11-19 |
GB9800584D0 (en) | 1998-03-11 |
JPH11509483A (en) | 1999-08-24 |
GB2317359A (en) | 1998-03-25 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6225595B1 (en) | Shaped-beam laser texturing of magnetic media | |
US5875084A (en) | Magnetic recording disk having protrusions centered in respective depressions | |
US5108781A (en) | Process for manufacturing selectively textured magnetic recording media | |
EP0447025B1 (en) | Magnetic recording media and processes for manufacture thereof | |
KR100426716B1 (en) | Low resonance texturing of magnetic media | |
US6048255A (en) | Pulsed laser surface treatments for magnetic recording media | |
KR100553482B1 (en) | Magnetic media with randomly positioned texturing features | |
US6187413B1 (en) | Media landing zone with recess for texturing features | |
JP3199266B2 (en) | Laser surface treatment of magnetic recording media | |
US6381098B1 (en) | Laser textured transducing head slider | |
US5834731A (en) | Laser texturing apparatus with bernoulli holder | |
US5897798A (en) | Laser texturing apparatus employing a rotating mirror | |
US6205002B1 (en) | Disk drive with textured slider contact region | |
US5968608A (en) | Laser texturing of magnetic recording medium using multiple lens focusing | |
US6165583A (en) | Surface modification of magnetic recording substrates to control subsequent laser texturing | |
US5945197A (en) | Laser texturing of magnetic recording medium using multiple lens focusing | |
JP2001357516A (en) | Method for assembling substrate surface of glass substrate | |
EP0962916A1 (en) | Laser texturing of magnetic recording medium using multiple lens focusing | |
GB2357183A (en) | Low resonance texturing of magnetic media | |
JPH09167342A (en) | Formation of projection of magnetic recording medium and magnetic recording medium | |
KR20000010874A (en) | Laser texturing of magnetic recording medium using multiple lens focusing | |
KR20000016322A (en) | Textured magnetic recording medium having a transition zone |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): DE GB JP KR SG US |
|
ENP | Entry into the national phase |
Ref document number: 1997 541145 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1019980700234 Country of ref document: KR |
|
RET | De translation (de og part 6b) |
Ref document number: 19780476 Country of ref document: DE Date of ref document: 19981015 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 19780476 Country of ref document: DE |
|
WWP | Wipo information: published in national office |
Ref document number: 1019980700234 Country of ref document: KR |
|
WWE | Wipo information: entry into national phase |
Ref document number: 08849001 Country of ref document: US |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1019980700234 Country of ref document: KR |