Disk surface defect inspection method and apparatus

A disk surface defect inspection apparatus comprising:

• a laser light source which irradiates a laser beam from an oblique direction onto a disk surface being rotated;
• a first optical receiver which receives a first light that is scattered with low-angle from the disk surface;
• a second optical receiver which receives the first light with lower sensitivity than the first optical receiver;
• a third optical receiver which receives a second light that is scattered with high-angle from the disk surface;
• a fourth optical receiver which receives the second light with lower sensitivity than the third optical receiver;
• and
• a controller which obtains a ratio of an output of the second optical receiver to an output of the fourth optical receiver, determines that a defect is a minute convex defect if the ratio of the output of the second optical receiver to the output of the fourth optical receiver is constant, and determines that the defect is a minute concave defect if the ratio of the output of the second optical receiver to the output of the fourth optical receiver is changed.

A disk surface defect inspection apparatus comprising:

• a laser light source which irradiates a laser beam from an oblique direction onto a disk surface being rotated;
• a first optical system which allows a first light that is scattered with low-angle by the laser beam from the disk surface to pass through or reflect;
• a first optical receiver which receives the first light which passes through the first optical system;
• a second optical receiver which receives the first light with sensitivity lower than the first optical receiver, the second optical receiver receiving the first light which is reflected by the first optical system;
• a second optical system which allows a second light that is scattered with high-angle by the laser beam from the disk surface to pass through or reflect;
• a third optical receiver which receives the second light which passes through the second optical system;
• a fourth optical receiver which receives the second light with sensitivity lower than the third optical receiver, the fourth optical receiver receiving the second light which is reflected by the second optical system;
• and
• a controller which obtains a ratio of an output of the second optical receiver to an output of the fourth optical receiver, determines that a defect is a minute convex defect if the ratio of the output of the second optical receiver to the output of the fourth optical receiver is constant, and determines that the defect is a minute concave defect if the ratio of the output of the second optical receiver to the output of the fourth light optical receiver is changed.