Method and apparatus for measuring melt level
US6994748B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 2001 |
| Grant date | Feb 7, 2006 |
| Priority date | — |
| Expiry date | Feb 19, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1004
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A melt level or the gap between a melt surface and a heat shield is measured accurately irrespective of how the melt surface is. A laser beam from a range-finding unit is reflected by a scanning mirror and projected on a melt surface through an entrance window and a quartz prism in a chamber of a puller. After specular reflection, the beam forms a measurement spot in the bottom of a heat shield and scatters. Part of the scatter, after specular reflection at the melt surface (secondary reflection), passes through the prism, the entrance window and the scanning mirror to the range-finding unit. The range-finding unit carries out triangulation using the distance between a laser source and a photodetector therein, and the angle of incidence and the angle of the received laser beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.