ND filter of optical film laminate type with carbon film coating
US7440204B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 16, 2005 |
| Grant date | Oct 21, 2008 |
| Priority date | — |
| Expiry date | Jun 28, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B9/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An ND filter is composed of a transparent substrate, a laminate of a light-absorbing film and a dielectric film formed on the transparent substrate, and a carbon film formed to clad a surface of the laminate of the light-absorbing films and the dielectric films. Depending on cases, another carbon film is also formed on a reverse side of the transparent substrate. The carbon film is formed by a deposition process at a deposition temperature ranging from a room temperature to 150° C. The light-absorbing film is formed of a mixture of metal and compound thereof, a material of the metal being selected from a group consisting of Ti, Cr, Ni, NiCr, NiFe, and NiTi. The dielectric film is formed of SiO2 or Al2O3.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.