Sensitive and fast response optical detection of transient motion from a scattering surface by two-wave mixing
US5680212A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1996 |
| Grant date | Oct 21, 1997 |
| Priority date | — |
| Expiry date | Apr 15, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P3/366
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus are provided of optically detecting transient motion from the surface of a workpiece. After directing a laser beam onto a surface of a workpiece the beam is reflected from it and then interferes with a pump beam removed from the laser source, inside a real-time holographic material, so as to form a grating diffracting the pump beam into a reference beam, which interferes at the output of the real-time holographic material with the received light beam, so as to produce a signal representative of the surface transient motion. An electric field is applied to the holographic material of sufficient magnitude to increase substantially the intensity of said reference beam and to give to this beam a phase differing substantially from the phase of said received light beam. The electric field is applied prior to the transient motion to be detected, for a time interval sufficiently long so as to capture the transient motion but sufficiently short a duration so as to avoid excessive heating of the real-time holographic material. The pump beam is of sufficiently high intensity so as to cause the response time of the real-time holographic material to be substantially short…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.