Acoustic image recorders
US4179936A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 18, 1978 |
| Grant date | Dec 25, 1979 |
| Priority date | — |
| Expiry date | May 18, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S15/8968
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of sensing changes in an object comprising irradiating the object with a focused beam of acoustic radiation excited by a first alternating electric signal; receiving a beam of acoustic radiation modulated in phase and amplitude by the object in the vicinity of the focus and deriving a second alternating electric signal therefrom; providing a reference electric signal derived from the first alternating electric signal and at a known phase; mixing coherently the second signal and the reference signal to derive a first in-phase signal; mixing the second signal with the reference signal altered in phase by between 80.degree. and 100.degree. to provide a first quadrature signal; storing the first in-phase and first quadrature signals; after an interval of time receiving a beam of acoustic radiation modulated by the same part of the object and deriving a third alternating electric signal therefrom and similarly deriving second in-phase and second quadrature signals; and combining the stored first and the second signals so as to sense any change in the object.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.