Compact image projection apparatus
US4171870A · kind A · utility
32Cited by
7References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 6, 1977 |
| Grant date | Oct 23, 1979 |
| Priority date | — |
| Expiry date | May 6, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A compact image projection apparatus comprises a concave spherical mirror, a plano-convex lens, a quarter wave plate and two prisms one of which is a roof prism. The apparatus is such that object and image have the same orientation and are positioned in two parallel planes. The apparatus is located, for example, between a mask and a semiconductor wafer in a scanning projection printing system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.