Method and system for laser marking in the volume of gemstones such as diamonds
US7284396B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 2005 |
| Grant date | Oct 23, 2007 |
| Priority date | — |
| Expiry date | Aug 22, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/87
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and an apparatus for laser marking indicia in the volume of gemstones such as diamonds, the indicia being made up of a plurality of microscopic dot-shaped marks whose build-up can be initiated by exposing naturally-occurring internal defects or impurities in the volume of a gemstone to a tightly focused train of laser pulses. Authentication data is encoded in the gemstone from the relative spatial arrangement of the dot-shaped marks that form the indicium. Taking advantage of the presence of otherwise invisible defects in the gemstone allows for inscribing indicia with laser pulses carrying energies substantially lower than the threshold energy required for inscribing in the volume of a perfect gemstone material. The marking process is then much less susceptible to inflict damages to the surface of the gemstone, and the marking can be performed using a broad variety of femtosecond laser systems. The dot-shaped marks engraved at a depth below the surface of a gemstone can be made undetectable with the unaided eye or with a loupe by limiting their individual size to a few micrometers, while devising indicia made up of only a few marks. As a result, the marking does not detra…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.