Disk film optical measurement system

A method of evaluating in at least one of lubricant coating thickness and coating wear on magnetic media disks subject to variable environmental and test conditions, such method comprising:

• A) providing a magnetic media disk including
• i) a magnetic media layer,
• ii) a coating layer overlying said magnetic media layer, and
• iii) a lubricant layer overlying said coating layer;
• B) supporting said magnetic media disk for rotation about a central axis extending normal to the substrate plane of said disk, and positioned for relative translation orthogonally of said axis with respect to a light source, said supporting being operable to selectively rotate said magnetic media disk about said axis as illumination is independently translated on said rotating disk orthogonally of said axis;
• C) generating a collimated light beam with the light source displaced from said magnetic media disk;
• D) in response to changes in environmental temperature, modifying the temperature of said light source to maintain a generally constant temperature thereof and, operating at said generally constant temperature, stabilizing said light source to
• i) maintain a constant intensity of light in said collimated light beam;
• and
• ii) maintain a constant wavelength of light in said collimated light beam;
• E) polarizing said collimated light beam emanating from said temperature stabilized light source to provide polarized light;
• F) providing position indicating means operable to determine a particular location on said disk upon which said polarized light impinges;
• G) providing a light collector displaced from said disk upon which said polarized light impinges, said light collector having
• i) an effective light receiving aperture having a width larger than width of said light beam so as to be operable to fully receive said beam, and
• ii) light intensity measuring means operative on received light;
• H) in a measurement, with respect to said particular location on said disk, directing said polarized light against said disk at said particular location and, during said measurement,
• i) reflecting said polarized light from said particular disk location, through said effective light receiving aperture of said light collector, and
• ii) measuring the amplitude of said received polarized light during said measurement;
• and
• I) determining at least one of wear of said coating layer and change in lubricant layer thickness at said particular disk location at least partially in response to said amplitude measurement.

A method of evaluating in at least one of lubricant coating thickness and coating wear on magnetic media disks subject to variable environmental and test conditions, such method comprising:

• A) providing a magnetic media disk including
• i) a magnetic media layer,
• ii) a coating layer overlying said magnetic media layer, and
• iii) a lubricant layer overlying said coating layer;
• B) supporting said magnetic media disk for rotation about a central axis extending normal to the substrate plane of said disk, and positioned for relative translation orthogonally of said axis with respect to a light source, said supporting being operable to selectively rotate said magnetic media disk about said axis as illumination is independently translated on said rotating disk orthogonally of said axis;
• C) generating a collimated light beam with the light source displaced from said magnetic media disk;
• D) controlling a cooler to maintain a generally constant temperature of said light source, and stabilizing said light source to
• i) maintain a constant intensity of light in said collimated light beam, and
• ii) maintain a constant wavelength of light in said collimated light beam;
• E) polarizing said collimated light beam emanating from said temperature stabilized light source to selectively provide
• i) p-polarized light, and
• ii) s-polarized light;
• F) providing position indicating means operable to determine a particular location on said disk upon which said polarized and collimated light beam impinges;
• G) providing an integrating sphere displaced from said disk upon which said beam impinges, said integrating sphere having
• i) a light receiving aperture having an axis inclined relative to said plane of said disk and a width larger than the width of said light beam so as to be operable to fully receive said beam from diverse, radially displaced light beam impingement locations on said disk, said aperture being generally axially intersected by specularly reflected light from said disk, and
• ii) light intensity measuring means defined by at least a portion of the interior of said integrating sphere;
• H) in a first measurement, and in respect to said particular location on said disk directing said polarized and collimated light beam against said disk at said particular location and, during said first measurement,
• i) reflecting said light beam from said particular disk location, through said light receiving aperture of said integrating sphere, and into the interior of said integrating sphere, and
• ii) independently measuring the amplitude of each of said p-polarized and said s-polarized light impinging upon the interior of said integrating sphere during said first measurement;
• I) subsequent to a period of rotation of said disk and in a second measurement with respect to said particular location on said disk, directing said polarized and collimated light beam again against said disk at said particular location and, during said second measurement
• i) reflecting said light beam from said first disk location, through said light receiving aperture of said integrating sphere, and into the interior of an integrating sphere, and
• ii) independently measuring the amplitude of each of said p-polarized and said s-polarized light impinging upon the interior of said integrating sphere during said second measurement;
• J) determining the difference in amplitude of each of said p-polarized and said s-polarized light increments impinging upon said interior of said integrating sphere during first and second measurements;
• and
• K) determining at least one of wear of said coating layer and change in lubricant layer thickness at said particular disk location in response to at least one of
• i) a difference in amplitude between said first and second measurements, of said p-polarized light impinging upon said interior of said integrating sphere;
• and
• ii) a difference in amplitude between said first and second measurements, of said s-polarized light impinging upon the interior of said integrating sphere.

A method of evaluating in at least one of lubricant coating thickness and coating wear on magnetic media disks subject to variable environmental and test conditions, such method comprising:

• A) providing a magnetic media disk including
• i) a magnetic media layer,
• ii) a coating layer overlying said magnetic media layer, and
• iii) a lubricant layer overlying said coating layer;
• B) supporting said magnetic media disk for rotation about a central axis extending normal to the substrate plane of said disk, and positioned for relative translation orthogonally of said axis with respect to a light source, said supporting being operable to selectively rotate said magnetic media disk about said axis as illumination is independently translated on said rotating disk orthogonally of said axis;
• C) generating a collimated light beam with the light source displaced from said magnetic media disk;
• D) maintaining a generally constant temperature of said light source and stabilizing said light source to
• i) maintain a constant intensity of light in said collimated light beam, and
• ii) maintain a constant wavelength of light in said collimated light beam;
• E) polarizing said collimated light beam emanating from said temperature stabilized light source to provide polarized light;
• F) providing position indicating means operable to determine a particular location on said disk upon which said polarized light impinges;
• G) providing an integrating sphere displaced from said disk upon which said polarized light impinges, said integrating sphere having
• i) a light receiving aperture having an axis inclined relative to said plane of said disk and a width larger than the width of said light beam and operable to fully receive said beam from diverse, radially displaced light beam impingement locations on said disk, said aperture being generally axially intersected by the specular polarized light reflected from said disk, and
• ii) light intensity measuring means defined by at least a portion of the interior of said integrating sphere;
• H) in a measurement, with respect to said particular location on said disk, directing said polarized light against said disk at said particular location and, during said measurement,
• i) reflecting said polarized light from said particular disk location, through said light receiving aperture of said integrating sphere, and into the interior of said integrating sphere, and
• ii) measuring the amplitude of said polarized light impinging upon the interior of said integrating sphere during said measurement;
• and
• I) determining at least one of wear of said coating layer and change in lubricant layer thickness at said particular disk location at least partially in response to said amplitude measurement.

Apparatus for evaluating at least one of lubricant coating thickness and coating wear on a magnetic media disk subject to variable environmental and test conditions, the magnetic media disk including i) a magnetic media layer, ii) a coating layer overlying said magnetic media layer, and iii) a lubricant layer overlying said coating layer, and such apparatus comprising:

• means for supporting said magnetic media disk for rotation about a central axis extending normal to the substrate plane of said disk, and positioned for relative translation orthogonally of said axis with respect to a light source, said means for supporting being operable to selectively rotate said magnetic media disk about said axis as illumination is independently translated on said rotating disk orthogonally of said axis;
• means for generating a collimated light beam with the light source displaced from said magnetic media disk;
• means for polarizing said collimated light beam emanating from said light source to provide polarized light;
• position indicating means for determining a particular location on said disk upon which said polarized light impinges;
• an integrating sphere displaced from said disk upon which said polarized light impinges, said integrating sphere having
• i) a light receiving aperture having an axis inclined relative to said plane of said disk and a width larger than width of said light beam so as to be operable to fully receive said beam from diverse, radially displaced light beam impingement locations on said disk, said aperture being generally axially intersected by the specular polarized light reflected from said disk, and
• ii) light intensity measuring means defined by at least a portion of the interior of said integrating sphere;
• means for determining a measurement with respect to said particular location on said disk by directing said polarized light against said disk at said particular location and, during said measurement,
• i) reflecting said polarized light from said particular disk location, through said light receiving aperture of said integrating sphere, and into the interior of said integrating sphere, and
• ii) measuring the amplitude of said polarized light impinging upon the interior of said integrating sphere during said measurement, said means for determining compiling a map of disk locations and detected amplitudes over said disk, said map determining at least one of wear of said coating layer and change in lubricant layer thickness at said particular disk location at least partially in response to said amplitude measurement.

Apparatus for evaluating at least one of lubricant coating thickness and coating wear on a magnetic media disk subject to variable environmental and test conditions, the magnetic media disk including i) a magnetic media layer, ii) a coating layer overlying said magnetic media layer, and iii) a lubricant layer overlying said coating layer;

• wherein the apparatus comprises
• means for supporting said magnetic media disk for rotation about a central axis extending normal to the substrate plane of said disk, and positioned for relative translation orthogonally of said axis with respect to a light source, said supporting means being operable to selectively rotate said magnetic media disk about said axis as illumination is independently translated on said rotating disk orthogonally of said axis;
• means for generating a collimated light beam with the light source displaced from said magnetic media disk;
• means for sensing temperature and modifying the temperature of said light source to maintain a generally constant temperature thereof and, operating at said generally constant temperature, means for stabilizing driving of said light source to
• i) maintain a constant intensity of light in said collimated light beam;
• and
• ii) maintain a constant wavelength of light in said collimated light beam;
• means for polarizing said collimated light beam emanating from said temperature stabilized light source to provide polarized light;
• position indicating means operable to determine a particular location on said disk upon which said polarized light impinges;
• a light collector displaced from said disk upon which said polarized light impinges, said light collector having
• i) an effective light receiving aperture having a width larger than width of said light beam so as to be operable to fully receive said beam, and
• ii) light intensity measuring means operative on received light;
• means for determining a measurement, with respect to said particular location on said disk by directing said polarized light against said disk at said particular location and, during said measurement,
• i) reflecting said polarized light from said particular disk location, through said effective light receiving aperture of said light collector, and
• ii) measuring the amplitude of said received polarized light during said measurement;
• said means for determining compiling a map of disk locations and detected amplitudes over said disk for determining at least one of wear of said coating layer and change in lubricant layer thickness at particular disk locations at least partially in response to said amplitude measurement.