1. A method of determining correction factors for servo control of a transducer in a disk drive that has a recording medium configured with multiple tracks and a transducer head controlled with a servo control signal, the servo control signal being generated based on an adaptive runout compensation algorithm and correction factors, the method comprising the steps of:
(a) successively positioning a transducer head over one or more tracks in a group and, for each track, allowing the adaptive runout compensation algorithm to adapt to a runout of said track for a first number of revolutions of the recording medium;
(b) after step (a), stepping the transducer head to be moved over one track and allowing the adaptive runout compensation algorithm to adapt to a runout of said track for a second number of revolutions of the recording medium; and
(c) after step (b), determining the correction factors,
wherein said step (a) includes:
designating one of the tracks in the group at an innermost diameter or outermost diameter of the group as an initial track;
positioning the transducer head over a track in the group that is N tracks away from the initial track and waiting for the second number of revolutions of the recording medium; and
successively repositioning the transducer head over an adjacent track in the group that is closer to said initial track and waiting for one revolution of the recording medium,
wherein N is 2 to 5 times greater than the number of revolutions of the recording medium that is needed by the adaptive runout compensation algorithm to adapt to a particular track of the group and the second number of revolutions is at least 10 times smaller than the number of revolutions of the recording medium that is needed by the adaptive runout compensation algorithm to adapt to a particular track of the group.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An antireflection film provided between a metal film having a complex refractive index represented by NM=nM\u2212i\xb7km and a glass substrate having a refractive index NG, wherein the metal film is an exposed surface of the antireflection film and includes a metal film component selected from the group consisting of molybdenum and a nickel alloy, comprising, from the metal film side:
(A) a first dielectric layer having a refractive index N1;
(B) a second dielectric layer provided on the first dielectric layer and having a refractive index N2; and
(C) a third dielectric layer provided on the second dielectric layer and having a refractive index N3,
wherein N1<nM, N1>NG, N2<NG, and N3>NG hold, whereby light which is incident on the glass substrate and which reaches the metal film is prevented from being reflected by the metal film, and
wherein 4.29\u2266N1+N3\u22664.75 holds.
2. The antireflection film according to claim 1, wherein 1.51<N1<3.53 holds.
3. The antireflection film according to claim 1, wherein, when a wavelength of the incident light is represented by \u03bb, an optical admittance Y1 obtained when the first dielectric layer has a minimum thickness at which a reflectance of a laminated structure of the metal film and the first dielectric layer is minimized and an optical admittance Y2 obtained from a laminated structure of the glass substrate, the third dielectric layer having an optical thickness of \u03bb4, and the second dielectric layer having an optical thickness of \u03bb4 satisfy the following equation
|Y1\u2212Y2|\u03b1\u22660.04
where \u03b1\u2261(nM2+kM2+N12)(2\xd7nM) holds.
4. The antireflection film according to claim 3, wherein the optical admittances Y1 and Y2 are represented by the following equations:
Y1=\u03b1\u2212{(nM\u2212\u03b1)2+kM2}12 and Y2=(NG\xd7N22)N32, respectively.
5. The antireflection film according to claim 1, wherein the metal film component includes molybdenum,
the second dielectric layer includes MgF2,
nM=3.53\xb10.10, kM=3.30\xb10.10, NG=1.51\xb10.10, and N2=1.38\xb10.10 hold, and 4.29\u2266N1+N3\u22664.40 holds.
6. The antireflection film according to claim 5, wherein the combination, between a material forming the first dielectric layer and a material forming the third dielectric layer, is (TiO2, SiOx), (Nb2O5, Ta2O5), (Nb2O5, ZrO2), (CeO2, Ta2O5), (CeO2, ZrO2), (Ta2O5, Nb2O5), (Ta2O5, CeO2), (ZrO2, Nb2O5) or (ZrO2, CeO2).
7. The antireflection film according to claim 1, wherein the metal film component includes molybdenum,
the second dielectric layer includes SiOx,
nM=3.53\xb10.10, kM=3.30\xb10.10, NG=1.51\xb10.10, and N2=1.46\xb10.10 hold, and 4.4\u2266N1+N3\u22664.6 holds.
8. The antireflection film according to claim 7, wherein the combination, between a material forming the first dielectric layer and a material forming the third dielectric layer, is (Nb2O5, Nb2O5), (Nb2O5, CeO2), (CeO2, CeO2), or (CeO2, Nb2O5).
9. The antireflection film according to claim 1, wherein 7.08\u2266nM+N1+N3\u22668.28 holds.
10. The antireflection film according to claim 1, further comprising a second antireflection film on a surface of the glass substrate opposite to that on which the third dielectric layer is provided.
11. The antireflection film according to claim 10, wherein the glass substrate of a laminated structure composed of the second antireflection film, the glass substrate, the third dielectric layer, the second dielectric layer, the first dielectric layer, and the metal film has a curvature radius of 1.0\xd7105 m or more.
12. An antireflection film provided between a metal film having a complex refractive index represented by NM=nM\u2212i\xb7km and a glass substrate having a refractive index NG, wherein the metal film is an exposed surface of the antireflection film and includes a metal film component selected from the group consisting of molybdenum and a nickel alloy, comprising, from the metal film side:
(A) a first dielectric layer having a refractive index N1;
(B) a second dielectric layer provided on the first dielectric layer and having a refractive index N2; and
(C) a third dielectric layer provided on the second dielectric layer and having a refractive index N3,
wherein N1<nM, N1>NG, N2<NG, and N3>NG hold, whereby light which is incident on the glass substrate and which reaches the metal film is prevented from being reflected by the metal film,
wherein the second dielectric layer includes MgF2,
wherein nM=2.94\xb10.10, kM=2.92\xb10.10, NG=1.51\xb10.10, and N2=1.38\xb10.10 hold,
wherein 4.14\u2266N1+N3\u22664.25 holds, and
wherein the combination, between a material forming the first dielectric layer and a material forming the third dielectric layer, is (TiO2, Y2O3).