Arrangements for correction of focusing light beam, and system using the same
US6728171B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 27, 2002 |
| Grant date | Apr 27, 2004 |
| Priority date | — |
| Expiry date | Apr 22, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/094
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Focusing method and exposure apparatus for focusing both a parallel light beam and a non-parallel light beam through a movable objective lens onto an object. A negative feedback loop is provided which has a detector for receiving a reflection light beam of the non-parallel light beam passed through the movable objective lens, reflected at the object and passed through the movable objective lens, for generating a detection signal corresponding to a focus deviation of the non-parallel light beam, and a driver for receiving the detection signal to control a position of the movable objective lens in accordance with the detection signal, so that the detection signal is decreased. The negative feedback loop further includes a correction signal generator for generating a correction signal and supplying it to the negative feedback loop as a disturbance of the loop so that the parallel light beam is focused onto the object.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.