Liquid crystal diffraction lens element and optical head device
US7710536B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 2007 |
| Grant date | May 4, 2010 |
| Priority date | — |
| Expiry date | Dec 15, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A liquid crystal diffraction lens element and an optical head device, which can switch focal lengths of both of outgoing light and returning light by a single element, are provided.The liquid crystal lens element comprises transparent substrates 1a, 1b, a liquid crystal 4 sandwiched between the transparent substrates 1a, 1b, transparent electrodes 2a, 2b, birefringent Fresnel lens members 3a, 3b each having a Fresnel lens shape and made of a birefringent material, and a seal 5, wherein the extraordinary refractive index direction A of the birefringent Fresnel lens member 3a and the extraordinary refractive index direction B of the birefringent Fresnel lens member 3b are perpendicular to each other, and the alignment direction of the liquid crystal 4 at the interface between the liquid crystal 4 and the transparent substrate 1a is perpendicular to the alignment direction of the liquid crystal 4 at the interface between the liquid crystal 4 and the transparent substrate 1b.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.