Active fiber-optic opto-acoustic detector
US5732046A · kind A · utility
Inventors
Key dates
| Filing date | Apr 19, 1996 |
| Grant date | Mar 24, 1998 |
| Priority date | — |
| Expiry date | Apr 19, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R23/008
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An opto-acoustic detector includes a fiber laser having a cavity which includes an optical fiber having an active medium portion doped with a gain material so that the detector may be used in high frequency, high density arrays. The cavity is bounded by a frequency selective reflector and a broadband or frequency selective reflector adapted to be acoustically coupled to a medium supporting ultrasound radiation (i.e. acoustic waves). In one embodiment, the frequency selective reflector is a diffraction grating placed external to the optical fiber. In another embodiment, the frequency selective reflector is a narrowband reflector placed directly in the optical fiber. An acoustic signal enhancing feature which increases sensitivity of the detector is provided by utilizing a reflective membrane having a thickness substantially less than the acoustic wavelength, .lambda., as the broadband optical reflector. The membrane is displaced from a free end of the optical fiber in the cavity and a laser beam exiting therefrom is focused on the membrane with a spot size on the order of the optical fiber core diameter. In this way, the sensing area of the detector is essentially the cross-sectiona…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.