ND filter and aperture diaphragm apparatus
US7230779B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 2005 |
| Grant date | Jun 12, 2007 |
| Priority date | — |
| Expiry date | May 13, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/205
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An ND filter is made of a transparent substrate having a plane. An optical film is formed on the plane of the transparent substrate. The optical film has a lamination structure including a light absorption film and a dielectric film, and has a variable transmission density. A thickness of either the light absorption film or the dielectric film of the lamination structure is changed in an in-plane direction of the transparent substrate so that the transmission density of the optical film is controlled to vary in the in-plane direction. The light absorption film is composed of a material selected from Ti, Cr, Ni, NiCr, NiFe, NiTi and a mixture thereof, and the dielectric film is formed of SiO2, Al2O3 or a compound thereof.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.