Optical system for measuring a surface profile of an object using a converged, inclined light beam and movable converging lens
US4900940A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 16, 1988 |
| Grant date | Feb 13, 1990 |
| Priority date | — |
| Expiry date | May 16, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/24
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a system for measuring a surface profile of an object in relation to a reference surface, a laser beam emitted from a laser 1 is converged by a convergent lens 3 and is incident on the surface of the object at an incident angle. The laser beam reflected from the object surface is also converged by the convergent lens 3 on a reference position of a detector 5 to form a beam spot thereon. When the converged laser beam is incident on a trench of the object, the beam spot formed on the detector 5 is deviated from the reference position and the detector 5 generates a deviation signal in accordance with a deviation of the beam spot. The convergent lens 3 is moved by an actuator 8 in accordance with the position signal so that the beam spot on the detector 5 is moved to a reference position. The movement of the convergent lens 3 is detected by a position detector 5 which generates a position signal. A height signal processor 6 processes the deviation and position signals the generates a height signal denoting a height of the trench.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.