University of Massachusetts

Nan Wu

Xingwei Vivian Wang

Wenhui Wang

Kai Sun

In an embodiment, a sensor comprises a waveguide comprising a photoacoustic generation element disposed on the waveguide, the photoacoustic generation element comprising a photoabsorptive material; and a sensing element comprising an optical acoustic wave detector. In another embodiment, a sensing system comprises the sensor and a laser. In yet another embodiment, a method of sensing comprises providing the sensing system; heating the photoabsorptive material with a laser to generate an acoustic signal; sensing an intensity of laser light reflected by the optical acoustic wave detector to detect the acoustic signal; and determining a time of flight of the acoustic signal between the generation and the detection to determine a change in a parameter change in a medium between the photoabsorptive material and the optical acoustic wave detector.

Distributed fiber sensor

An optical fiber sensor can be used to measure pressure with high sensitivity and fine resolution. As a cavity at the end of the sensor expands or contracts, the spectrum of a beam reflected from the end of fiber shifts, producing a change linked to pressure exerted on the sensor. Novel aspects of the present inventive sensor include the direct bonding of a silica thin film diaphragm to the optical fiber with localized or confined heating and a uniform thickness of the diaphragm. The resulting sensor has a diameter that matches the diameter of the optical fiber. Because the sensor is all silica, it does not suffer from temperature-induced error. In addition, the sensor can be very sensitive because the diaphragm can be very thin; it can also make highly repeatable measurements due to its very uniform thickness.

Optical fiber pressure sensor with uniform diaphragm and method of fabricating same

A photoacoustic transducer, such as a photoacoustic probe includes an optical fiber, diaphragm, at the optical fiber, whereby the optical fiber and diaphragm define a cavity, and an energy absorption film at the optical fiber, whereby an activating laser directed through the optical fiber can excite the energy absorption film to thereby generate an acoustic wave that, upon reflection upon a remote surface, can deflect the diaphragm and modify reflection of a detecting laser also directed through the optical fiber. A method of detecting an acoustic wave includes directing an activating laser through an optical fiber to an energy absorption film at the optical fiber, directing a detecting laser through the optical fiber and cavity to the diaphragm at the optical fiber, and measuring an interference pattern generated at least in part by reflection of the detecting laser from a surface of the diaphragm.

Photoacoustic probe

An optical fiber sensor () can be used to measure pressure with high sensitivity and fine resolution. As a () at the end of the sensor expands or contracts, the spectrum of a beam reflected from the end of fiber shifts, producing a change linked to pressure exerted on the sensor. Novel aspects of the present inventive sensor include the direct bonding of a silica thin film diaphragm () to the optical fiber with localized or confined heating and a uniform thickness of the diaphragm. The resulting sensor has a diameter that matches the diameter of the optical fiber. Because the sensor is all silica, it does not from temperature-induced error. In addition, the sensor can be very sensitive because the diaphragm can be very thin; it can also make highly repeatable measurements due to its very uniform thickness.

Growing community of inventors

Lowell, MA, United States of America

Nan Wu