Optical extensometer
US4129384A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 8, 1977 |
| Grant date | Dec 12, 1978 |
| Priority date | — |
| Expiry date | Jun 8, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical extensometer is described using sequentially pulsed light beams for measuring the dimensions of objects by detecting two opposite edges of the object without contacting the object. The light beams may be of different distinguishable light characteristics, such as polarization or wave length, and are time modulated in an alternating manner at a reference frequency. The light characteristics are of substantially the same total light energy and are distributed symmetrically. In the preferred embodiment two light beam segments of one characteristic are on opposite sides of a middle segment of another characteristic. As a result, when the beam segments are scanned sequentially across two opposite edges of the object, they produce a readout signal at the output of a photoelectric detector that is compared with the reference signal by a phase comparator to produce a measurement signal with a binary level transition when the light beams cross an edge. The light beams may be of different cross sectional geometries, including two superimposed and concentric circular beam cross sections of different diameter, or two rectangular cross sections which intersect with each other substan…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.