Deformation measuring method and device using cross-correlation function between speckle patterns with reference data renewal
US4967093A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 19, 1989 |
| Grant date | Oct 30, 1990 |
| Priority date | — |
| Expiry date | Jun 19, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/162
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a deformation measuring method and device in which an object is irradiated with a laser beam before and after deformation of the object to obtain speckle patterns, the speckle patterns thus obtained are photoelectrically converted into electrical signals, and the cross-correlation function between the speckle patterns is calculated using the electrical signals to obtain displacement of the speckle pattern on the basis of the shift of position of the extreme value of the mutual-correlation function and to determine the amount of deformation of the object from the displacement of the speckle pattern, (1) the reference speckle pattern data for calculation of the cross-correlation function is renewed when the extreme value of the cross-correlation function is lower in level than a predetermined value or when the position of the extreme value is out of a predetermined range, or (2) the reference speckle pattern data is renewed when the extreme value of the cross-correlation function is lower in level than a predetermined value and a calculation range for calculating the cross-correlation function is shifted when the position of the extreme value is out of a predetermined range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.