Apparatus and method for surface inspection by specular interferometric and diffuse light detection
US5875029A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1997 |
| Grant date | Feb 23, 1999 |
| Priority date | — |
| Expiry date | Aug 11, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/1045
- WIPO fieldMeasurement
- WIPO sectorInstruments
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. 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. Both the angle and power of the specular reflected light are measured, while just the power of the dif…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.