Surface inspection apparatus
US4829374A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 12, 1987 |
| Grant date | May 9, 1989 |
| Priority date | — |
| Expiry date | Nov 12, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B21/244
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A surface inspection apparatus having a microscope and a television camera is disclosed. The inspection apparatus samples a signal portion from a horizontal scanning portions of the video signal produced by the television camera, compares the instantaneous voltages of a filtered signal of said sampled portion removing low-frequency components with a reference voltage, counts the number of pulses constituted from the high level portions of said filtered signal higher than said reference voltage sequentially moves the focal point of the microscope step by step relative to the object surface, compares the present pulse count with the previous pulse count thereof at just prior step of the moving of the focal point, and decides the focal point in the position corresponding to the maximum number of pulses to control the moving of the focal point for correctly setting the focal point in said corresponding position.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.