Optical inspection method utilizing ultraviolet light
US7206442B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 18, 2002 |
| Grant date | Apr 17, 2007 |
| Priority date | — |
| Expiry date | Nov 26, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/956
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system and method for inspecting structures formed on the surface of an object using ultraviolet (UV) light. The object is placed in position and illuminated with at least one wavelength of UV light, directed at its surface from a UV source. At the moment of illumination, an image is captured by a UV-light sensitive camera positioned at an angle calculated to intercept light diffracted at particular an angle of diffraction associated with the pattern of structures formed on the surface of the object. To avoid having to repeatedly reposition the camera, one (or more in succession) illumination wavelength is selected to direct an intensity peak associated with a particular order of diffraction at the camera location. Ideally, a visible-light sensitive camera is also used to capture images of the surface when illumination with UV light results in the emanation of light in the visible portion of the spectrum.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.