Apparatus and method for automatically focusing an interference microscope
US5122648A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 1990 |
| Grant date | Jun 16, 1992 |
| Priority date | — |
| Expiry date | Jun 1, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B21/241
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Automatic focusing of an interference microscope is accomplished by directly sensing an interference pattern produced by a white light source with an auxiliary point detector. A beamsplitter intercepts part of the interference beam and directs it to the point detector. A narrow band filter filters light passing through the beam splitter on its way to a main detector array. An objective of the interference microscope is rapidly moved to an initial position between a sample surface and a fringe window by operating a position sensor to sense when the objective is a predetermined safe distance from the sample surface and turning off a motor moving the objective. The objective then moves rapidly from the initial position until the presence of fringes is detected by the point detector. Momentum of the microscope causes the objective to overshoot beyond a fringe window. The microscope objective then is moved more slowly through the interference window until fringes again are detected; the lower speed results in substantially reduced overshoot. Intensity measurements from the detector are sensed and stored as the objective moves through the width of the fringe window. The microscope object…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.