Optical scanning unit comprising a translational-position and angular-position detection system for an electro-magnetically suspended objective
US4638471A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 26, 1985 |
| Grant date | Jan 20, 1987 |
| Priority date | — |
| Expiry date | Aug 26, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/09
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical scanning unit is described, which unit comprises a radiation source (1), an objective lens (3) and a translational-position and angular-position detection system for determining the translational position and the angular position of the objective lens within the scanning unit. This system comprises a conical-ring mirror (5) which is centered and fixed relative to the objective lens and a radiation-sensitive detection system (9) which is arranged in the path of the radiation reflected from the mirror and which comprises two detectors which are spaced by an annular strip (12) and are each divided into four quadrants (13-20). The scanning unit further comprises an electromagnetic system comprising an annular permanent magnet (70) around the objective lens and at least six magnet coils (71-76) which are arranged in two axially shifted planes (80, 81).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.