Composite imaging mask
US5118935A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 28, 1991 |
| Grant date | Jun 2, 1992 |
| Priority date | — |
| Expiry date | Feb 28, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/005
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A novel composite imaging mask suitable for employment in a method for simultaneously determining coarse and fine petal piston in a segmented imaging assembly. The mask comprises a transparent substrate comprising two spaced-apart apertures, which apertures are dedicated to coarse petal alignment; a first overlay deposited on a face of the substrate, for defining four phase retardation regions dedicated to fine petal alignment; a second overlay comprising an opaque coating, the second overlay deposited on the face of the substrate and complementary to the four phase retardation regions and the apertures, and a means for spirally separating the coarse and fine alignment entities.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.