Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks, a spacer, a hub, and a clamp. Each of the magnetic disks includes a through-hole in a center section thereof. The spacer is disposed among the magnetic disks, and includes a through-hole in a center section thereof. The hub is inserted into the through-holes of the magnetic disks and the spacers. The clamp presses and holds the magnetic disks and the spacer. At surfaces where the magnetic disks and the spacer or the clamp contact, a flat surface height of an upper surface of at least one magnetic disk that contacts an outer circumference of the spacer or the clamp is lower than a flat surface height of the upper surface of at least one magnetic disk of the magnetic disks that contacts an inner circumference of the spacer or the clamp.

Abstract: An aluminum alloy disc blank for a magnetic disc made of an aluminum alloy containing Fe: 0.005 to 1.800 mass % with the balance being Al and inevitable impurities, wherein a flatness change of the aluminum alloy disc blank for a magnetic disc when the aluminum alloy disc blank for a magnetic disc is held in the atmosphere at 50° C. or lower for 336 hours is 2.0 ?m or less.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks 30, spacers 80, a hub 90, a clamp 70, and a fastening member 72. Each of the magnetic disks 30 includes a through-hole in a center section thereof. Each of the spacers 80 includes a through-hole in a center section thereof, and is disposed among the magnetic disks 30. The hub 90 is inserted into the through-holes of the magnetic disks 30 and the spacers 80. The clamp 70 presses and holds the magnetic disks 30 and the spacers 80. The fastening member 72 fastens the clamp 70 to the hub 90. The clamp 70 is fastened to the hub by the fastening member 72 with a torque of from 5 cN·m to 45 cN·m.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks, a spacer, a hub, and a clamp. Each of the magnetic disks includes a through-hole in a center section thereof. The spacer is disposed among the magnetic disks, and includes a through-hole in a center section thereof. The hub is inserted into the through-holes of the magnetic disks and the spacers. The clamp presses and holds the magnetic disks and the spacer. At surfaces where the magnetic disks and the spacer or the clamp contact, a flat surface height of an upper surface of at least one magnetic disk that contacts an outer circumference of the spacer or the clamp is lower than a flat surface height of the upper surface of at least one magnetic disk of the magnetic disks that contacts an inner circumference of the spacer or the clamp.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks 30, spacers 80, a hub 90, a clamp 70, and a fastening member 72. Each of the magnetic disks 30 includes a through-hole in a center section thereof. Each of the spacers 80 includes a through-hole in a center section thereof, and is disposed among the magnetic disks 30. The hub 90 is inserted into the through-holes of the magnetic disks 30 and the spacers 80. The clamp 70 presses and holds the magnetic disks 30 and the spacers 80. The fastening member 72 fastens the clamp 70 to the hub 90. The clamp 70 is fastened to the hub by the fastening member 72 with a torque of from 5 cN·m to 45 cN·m.

Abstract: There is provided a glass substrate for a magnetic disk in which a maximum height of bumps forming a roughness pattern at a period of smaller than 2 ?m is 6 nm or lower in an annular area having a width of 30 ?m on a main surface on which a magnetic recording area is formed, a number of bumps having a height of 3 nm or higher in a unit area having a circular arc length of 30 ?m within the annular area is one or less, and a difference in arithmetic average roughness between unit areas within the annular area is 0.2 nm or smaller.

Abstract: A connecting member which is formed by filling a mold with a resin composition and then solidifying the resin composition, the connecting member having one end face in which a plurality of fine holes of a ? or less are arrayed in a row with a pitch P therebetween, and guide pin insertion holes are formed on either side of the fine holes, wherein the resin composition is comprised of a resin and a filler mixed therein, and wherein the space (P?a) between the fine holes meets the following formula; Dm<(P?a)<Dmax, in which Dmax represents the largest diameter of the filler particles, and Dm represents the most frequent diameter of the filler particles.

Abstract: There is provided a glass substrate for a magnetic disk in which a maximum height of bumps forming a roughness pattern at a period of smaller than 2 ?m is 6 nm or lower in an annular area having a width of 30 ?m on a main surface on which a magnetic recording area is formed, a number of bumps having a height of 3 nm or higher in a unit area having a circular arc length of 30 ?m within the annular area is one or less, and a difference in arithmetic average roughness between unit areas within the annular area is 0.2 nm or smaller.

Abstract: A connecting member which is formed by filling a mold with a resin composition and then solidifying the resin composition, the connecting member having one end face in which a plurality of fine holes of a? or less are arrayed in a row with a pitch P therebetween, and guide pin insertion holes are formed on either side of the fine holes, wherein the resin composition is comprised of a resin and a filler mixed therein, and wherein the space (P?a) between the fine holes meets the following formula; Dm<(P?a)<Dmax, in which Dmax represents the largest diameter of the filler particles, and Dm represents the most frequent diameter of the filler particles.

Abstract: A connecting member which is formed by filling a mold with a resin composition and then solidifying the resin composition, the connecting member having one end face in which a plurality of fine holes of a ? or less are arrayed in a row with a pitch P therebetween, and guide pin insertion holes are formed on either side of the fine holes, wherein the resin composition is comprised of a resin and a filler mixed therein, and wherein the space (P?a) between the fine holes meets the following formula; Dm<(P?a)<Dmax, in which Dmax represents the largest diameter of the filler particles, and Dm represents the most frequent diameter of the filler particles.

Abstract: A connecting member which is formed by filling a mold with a resin composition and then solidifying the resin composition, the connecting member having one end face in which a plurality of fine holes of a ? or less are arrayed in a row with a pitch P therebetween, and guide pin insertion holes are formed on either side of the fine holes, wherein the resin composition is comprised of a resin and a filler mixed therein, and wherein the space (P?a) between the fine holes meets the following formula; Dm<(P?a)<Dmax, in which Dmax represents the largest diameter of the filler particles, and Dm represents the most frequent diameter of the filler particles.

Abstract: An end heating and processing method of an optical fiber preform. In this method, an optical fiber preform is processed by heating and melting an end of a vitrified optical fiber preform including a core portion and a cladding portion formed on an outer circumference thereof to process the end having a shape for drawing as an optical fiber.

Abstract: In a defect detecting method for detecting defect of a measured optical fiber, the defect of the optical fiber is detected on the basis of a pattern of the intensity distribution obtained by illuminating a laser beam on to the optical fiber, the pattern of the intensity distribution is subjected to a weak smoothing process and a strong smoothing process to form first and second pattern, respectively, and a judging pattern is formed on the basis of a difference or quotient between the first and second pattern, and then is subjected to Fourier transform to form a Fourier transform pattern which is evaluated by using double logarithmic axis, and judging curve having high contributing rate to the Fourier transform pattern is applied to the Fourier transform pattern, and the defect of the optical fiber is detected on the basis of magnitude of the dispersion of the Fourier transform pattern from the judging curve.

Abstract: In defect detecting method for detecting defect of an optical fiber to be measured, in which a laser beam is illuminated onto an optical fiber to be measured from a direction transverse to an optical axis of the fiber to check intensity distribution of forward scattering light permeated through within the optical fiber and scattered, and the defect of the optical fiber to be measured is detected on the basis of a pattern of the intensity distribution, the pattern of the intensity distribution is subjected to a smoothing process having weak smoothness and a smoothing process having strong smoothness to form first and second patterns, respectively, and a judging pattern is formed on the basis of a difference or the quotient between the first and second patterns, and the defect of the optical fiber to be measured is detected by evaluating magnitude of the judging pattern.

Abstract: A method for fiber drawing of an optical fiber, which method comprises:

Abstract: In defect detecting method for detecting defect of an optical fiber to be measured, in which a laser beam is illuminated onto an optical fiber to be measured from a direction transverse to an optical axis of the fiber to check intensity distribution of forward scattering light permeated through within the optical fiber and scattered, and the defect of the optical fiber to be measured is detected on the basis of a pattern of the intensity distribution, the pattern of the intensity distribution is subjected to a smoothing process having weak smoothness and a smoothing process having strong smoothness to form first and second patterns, respectively, and a judging pattern is formed on the basis of a difference or the quotient between the first and second patterns, and the defect of the optical fiber to be measured is detected by evaluating magnitude of the judging pattern.

Abstract: In defect detecting method for detecting defect of an optical fiber to be measured, in which a laser beam is illuminated onto an optical fiber to be measured from a direction transverse to an optical axis of the fiber to check intensity distribution of forward scattering light permeated through within the optical fiber and scattered, and the defect of the optical fiber to be measured is detected on the basis of a pattern of the intensity distribution, the pattern of the intensity distribution is subjected to a smoothing process having weak smoothness and a smoothing process having strong smoothness to form first and second patterns, respectively, and a judging pattern is formed on the basis of a difference or the quotient between the first and second patterns, and the defect of the optical fiber to be measured is detected by evaluating magnitude of the judging pattern.

Abstract: An end heating and processing method of an optical fiber preform. In this method, an optical fiber preform is processed by heating and melting an end of a vitrified optical fiber preform including a core portion and a cladding portion formed on an outer circumference thereof to process the end having a shape for drawing as an optical fiber.