Fresnel zone mask for pupilgram
US6048651A · kind A · utility
11Cited by
3References
25Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1998 |
| Grant date | Apr 11, 2000 |
| Priority date | — |
| Expiry date | Oct 23, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70141
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A test photomask comprising a fresnel zone target (FZT) pattern may be used to verify the adjustment of a precision projector illumination system of an image projection system. The method comprises the steps of creating the FZT pattern on a photomask, projecting a pupil diagram onto an image plane using the FZT pattern, and evaluating the pupil diagram to determine the illumination system adjustment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.