Abstract: A simple yet versatile non-contact optical inspection instrument and method are described for measuring the height and width of defects and contaminants on a magnetic disk surface. The instrument includes a sensor which produces an illumination beam that is modulated and then focused normally on the disk surface as a spot. The illumination spot is Doppler shifted due to the movement of the disk and the diffusely reflected light is interfered with a reference beam produced by the sensor's illumination optics. The sensor uses two collection optics channels which simultaneously detect both the specular reflected light and the diffuse scattered light produced by the disk surface. The phase shift of the specular reflected light and that of the diffusely scattered light are measured. The output signals from the sensors are processed to estimate the size and type of the defects. Another aspect of the present invention includes a demodulator which increases the frequency of an FM signal.

Abstract: A simple yet versatile noncontact optical inspection instrument and method are described for the inspection of magnetic disk surfaces for surface defects. This instrument is capable of inspecting the disk surface at any point in the disk manufacturing process. Surface defects such as bumps, pits and scratches can be measured. Surface contaminants such as particles and stains can also be measured. The instrument is also capable of discriminating between surface defects and surface contaminants. The instrument is comprised of two identical optical sensors which are located on opposite sides of the disk. A carriage supports and translates these sensors along the disk radius while a spindle rotates the disk. Both surfaces of the disk are therefore simultaneously scanned in a spiral fashion. The sensor's illumination optics produce a monochromatic focused spot of light which is normally incident upon the disk surface.

Abstract: A method and apparatus for detecting defects on the surface of a data recording medium. In one embodiment the present invention includes a sensor for detecting defects on the surface of a magnetic disk. The sensor generates an analog voltage signal that is representative of a surface anomaly detected on the disk surface. An analog signal processor processes the signal before it is received by a peak detecting circuit. The peak detecting circuit detects and converts a peak of the analog signal into digital data. The digital data is received and manipulated by a digital signal processor where the peak amplitude, average peak amplitude and average peak power of the defect may be calculated.

Abstract: An apparatus for testing the calibration of hard disk substrate tester includes a calibrating micrometer moving a known surface to at least two distances from a non-contact detector in the hard disk surface tester and a known distance from each other, and further includes a piezoelectric transducer mounted to the known surface moved by the calibrating micrometer, and an oscillator oscillating the surface at predetermined frequencies and amplitudes.

Abstract: A machine for automatically producing a bib apron and for affixing a narrow strip thereto to form both the neck loop and tie elements for the apron. The machine includes a cutting mechanism having a skewed roller carrying a cutting blade which makes point contact with a second roller to divide a continuous web of nonwoven fibrous material into separate rectangular sheets. The material for the strip is folded longitudinally and is then advanced across each sheet by a feed mechanism including a capstan drive and a clamping mechanism for holding the strip in juxtaposition with the sheet. Thereafter, the strip is contacted by a pull member which draws the center of the strip in a downstream direction to form a "V". The forward corners of the sheet are then folded over the legs of the V and are adhesively secured to the body of the sheet to hold the strip in place.