Abstract: An apparatus and method for measuring the space between a transparent member such as a substrate, and reflective member such as a slider. The apparatus includes a first optical system which detects a first light beam that is reflected from the substrate and the slider. The reflected light is separated into four separate beams. The intensities of the beams are detected and utilized to determine a first stokes parameter, a second stokes parameter, a third stokes parameter and a fourth stokes parameter of the reflected light. The stokes parameters are used to compute the real index of refraction n, extinction coefficient k and the thickness of the space. The four stokes parameters account for any depolarized light that is reflected from the slider. The first optical system may have a photodetector which detects an image of the slider. The image provides multiple data points that can be used to calculate n, k and the thickness of the air gap without a retract routine.

Abstract: An optical inspection apparatus detects anomalies by reflecting a beam of coherent light off the surface of a sample. An anomaly present on the surface causes the reflected beam to be diffracted at an angle which corresponds to a scale of the anomaly. An optical detection array is positioned to receive the reflected diffraction pattern and produce an electrical signal which corresponds to the diffraction angle of the reflected pattern. The electrical signal may then be processed to determine the location and scale of the anomaly from the detected diffraction angle.

Abstract: A preferred embodiment of the present invention comprises two laser sources of different frequency monochromatic light that are time-multiplexed through a beam combiner to produce composite beams that are steered to a gap between a slider and a disk. A reflected light that includes an interference pattern is then directed to an aperture plate that permits a spot of light to be directly detected by a photodiode which reads the intensity. Measurements of the intensity are taken at respective time-points to sample each laser source, and the measured intensities are compared to determine the slider to disk spacing. Since different frequency light will have different intensity for the same spacing, integer ambiguities can be directly resolved.

Abstract: An automatic surface inspection apparatus comprises a light source that provides a coherent light beam that is spit and then recombined in a prism to generate an interference pattern. A cylindrical lens projects the interference pattern onto the surface of a disk as a line of light. A linear detection array converts the reflected line of light into an electrical signal that has a magnitude which varies dependent upon the reflected light intensity. Defects present on the surface of the disk cause variations in the reflected light intensity manifested as differences in the electrical signal output by the detection array.

Abstract: A burnish head comprising a slider body having a single crystal diamond attached to a rear portion flies above the disk surface at a relatively low flying height when the disk is rotated at a high angular velocity. The diamond produces acoustic waves that cut or crack disk asperities, resulting in a highly-smooth disk surface suitable for near-contact or in-contact magnetic recording.