Minute step measuring method
US5694220A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1995 |
| Grant date | Dec 2, 1997 |
| Priority date | — |
| Expiry date | Oct 10, 2015 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB82Y15/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A minute step measuring method comprises forming a laser spot on an object by condensing light from a laser light source, condensing light beams from the object on an end face of a double-mode waveguide, branching light propagating in the double-mode waveguide into two channel waveguides, detecting light beams emerging from the two channel waveguides, and measuring a minute step existing on the object, using a signal of a difference and a signal of a sum between two signals according to the two light beams detected, wherein measurement is conducted of a signal W.sub.a of the sum when the laser spot is located on one of two flat portions existing before and after the step, and of a signal W.sub.b of the sum when the laser spot is located on the other flat portion, and wherein the step is measured by correcting a difference between reflectivities of the two flat portions existing before and after the step in measuring the minute step, using the signals W.sub.a and W.sub.b.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.