Method for detecting defects in a rod-shaped transparent object
US9939390B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 25, 2013 |
| Grant date | Apr 10, 2018 |
| Priority date | — |
| Expiry date | Jun 25, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/105
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for inspecting defects inside a rod-shaped transparent object by using a scanning beam of parallel light rays directed onto a rod-shaped transparent object orthogonally to the longitudinal axis of the object so that an inspection plane comprises an object's cross-section. The scanning beam is detected at an opposite side of the rod-shaped object that is interposed to intercept the parallel rays of the scanning beam. The electric output signal from the detector is processed to produce a first light intensity profile in a first scan direction, the light intensity profile comprising a shadow region delimited by first and second shadow edges, which is indicative of the outside diameter of the object across the inspection plane. The method comprises analyzing the first light intensity profile to determine the presence or absence of a peak of positive intensity within the shadow region and, if an intensity peak is determined to be present, to determine the presence or absence of a region of depressed intensity within the intensity peak. If, as a result of analyzing, an intensity peak within the shadow region is determined to be absent or a region of depressed intensity is determ…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.