Test object for use in detecting aberrations of an optical imaging system
US6331368A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 2001 |
| Grant date | Dec 18, 2001 |
| Priority date | — |
| Expiry date | Apr 27, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Aberrations of an imaging system (PL) can be detected in an accurate and reliable way by imaging, by means of the imaging system, a test object having circular phase structure (22) on a photoresist (PR), developing the resis and scanning it with a scanning detection device (SEM) which is coupled to an image processor (IP). The circular phase structure is imaged in a ring structure (25) and each of several possible aberrations, like coma, astigmatism, three-point aberration, etc. causes a specific change in the shape of the inner contour (CI) and the outer contour (CE) of the ring and/or a change in the distance between these contours, so that the aberrations can be detected independently of each other.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.