Method and apparatus for enhanced sensitivity fly height testing and measurement

A disk for use in an apparatus for performing interferometric measurement/testing of flying heights of read-write head sliders, said disk having a central opening for use with a spindle for rotation about a central axis, said disk comprising:

• a substrate comprised of a light transmissive material and including a pair of opposed, smooth, major surfaces;
• and
• a wear-resistant, protective overcoat layer on one of said major surfaces for improving the tribological properties thereof, wherein said protective overcoat layer comprises a diamond-like carbon (DLC) material having a high refractive index from about 1.8 to about 2.4, and said light transmissive substrate comprises a glass material having a high refractive index from about 1.9 to about 2.5, said high refractive index glass material being index-matched to said high refractive index DLC material of said protective overcoat layer;
• wherein the optical properties of said one surface of said disk are optimized for enhancing the sensitivity of said interferometric measurement/testing by increasing the intensity of reflected light received by a detector of said apparatus.

A disk for use in an apparatus for performing interferometric measurement/testing of flying heights of read-write head sliders, said disk having a central opening for use with a spindle for rotation about a central axis, said disk comprising:

• a substrate comprised of a light transmissive material and including a pair of opposed, smooth, major surfaces, wherein said light transmissive substrate comprises a glass material having a low refractive index from about 1.4 to about 1.6;
• a wear-resistant, protective overcoat layer on one of said major surfaces, wherein said protective overcoat layer comprises a diamond-like carbon (DLC) material having a high refractive index from about 1.8 to about 2.4;
• and
• said disk further comprises an underlayer of a material having a very high index of refraction from about 1.9 to about 2.6 and a very low extinction coefficient from about 0 to about 0.5 interposed between said one surface of said low refractive index glass substrate and said high refractive index, protective overcoat layer of DLC material.

An apparatus for performing interferometric measurement/testing of flying heights of read-write head sliders, comprising:

• a rotatable disk comprised of a light transmissive substrate material, wherein said light transmissive substrate comprises a glass material having a low refractive index from about 1.4 to about 1.6;
• wherein one side of said disk includes a protective overcoat layer, wherein said protective overcoat layer comprises a material having a high refractive index from about 1.8 to about 2.4;
• and
• said disk further comprises an underlayer of a material having a very high index of refraction from about 1.9 to about 2.6 and a very low extinction coefficient from about 0 to about 0.5 interposed between said one surface of said low refractive index glass substrate and said high refractive index, protective overcoat layer of DLC material.