Optical projection system including a refractive lens assembly having a gap between constituent lenses
US5161062A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 11, 1991 |
| Grant date | Nov 3, 1992 |
| Priority date | — |
| Expiry date | Jul 11, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B17/0892
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A photolithographic projection optical system comprising: a source of exposure energy for generating a beam of energy; an optical element located in the path of the beam for receiving the beam of energy and passing the beam therethrough; a refractive lens assembly located in the path of the portion of the beam for receiving and transmitting the beam of energy, the refractive lens assembly comprising at least one meniscus lens, a plano-convex lens, and an air gap disposed between the meniscus lens and the plano-convex lens; a reticle element located in the path of the portion of the beam, the reticle element having a uniform thickness and being positioned for permitting the beam to pass through the thickness and through the lens assembly to the optical element. Alternatively, the air gap of the refractive lens assembly can be replaced with a glass layer having an index of refraction that is lower than both the meniscus lens and the plano-convex lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.