Telecentric sub-field deflection with vail
US4859856A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1988 |
| Grant date | Aug 22, 1989 |
| Priority date | — |
| Expiry date | Jan 11, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J37/1474
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A two staqge, electron beam projection system includes a target, a source of an electron beam and means for projecting an electron beam towards the target with its upper surface defining a target plane. A magnetic projection lens has a principal plane and a back focal plane located between said means for projecting and the target. The means for projecting provides an electron beam directed towards the target. First stage means provides deflection of the beam from area to area within a field. Second stage means provides for deflection of the beam for providing deflection of the beam within an area within a field. The beam crossing the back focal plane produces a telecentric condition of the beam in the image plane with the beam substantially normal to the target plane from the principal plane to the target plane. The magnetic projection lens includes a magnetic structure providing for magnetic compensation positioned within the bore of the projection lens, which produces a compensating magnetic field substantially proportional to the first derivative of the axial magnetic projection field. The axial magnetic projection field provides substantially a zero first derivative of the axia…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.