Phase mask with spatially variable diffraction efficiency
US6545808B1 · kind B1 · utility
Assignees
Inventors
Key dates
| Filing date | Feb 10, 2000 |
| Grant date | Apr 8, 2003 |
| Priority date | — |
| Expiry date | Feb 10, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/1225
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A phase mask (15) for modulating a collimated light beam passing therethrough, the light beam being diffracted to photoinduce a refractive index profile in a photosensitive optical medium, the phase mask (15) comprises a substrate (17) having an outer surface provided with a plurality of parallel grating corrugations (19). The grating corrugations (19) have a non-uniform relief depth across the outer surface for photoinducing a non-uniform refractive index profile in the photosensitive optical medium. The non-uniform relief depth is defined by a variable thin film layer (21) of variable thickness overlaying the substrate (17). The grating corrugations (19) can either be etched into the variable thin film layer (21) itself or be etched into the substrate (17), with the variable this film layer (21) being deposited on it after etching. Methods to make such phase masks are also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.