Interferometric fiber optic sensors for biomedical applications of optoacoustic imaging

Abstract

We present a non-metallic interferometric silica optical fiber ultrasonic wideband sensor for optoacoustic imaging applications. The ultrasonic sensitivity of this sensor has been characterized over the frequency range from 1 to 10 MHz. A comparative analysis has been carried out between this sensor and an array of piezoelectric transducers using optoacoustic signals generated from an optical absorbent embedded in a tissue mimicking phantom. Also, a two dimensional reconstructed image of the phantom using the fiber interferometric sensor is presented and compared to the image obtained using the Laser Optoacoustic Imaging System, LOIS-64B. The feasibility of our fiber optic based sensor for wideband ultrasonic detection is demonstrated.

All-fiber ultrasound sensor array implemented by swept frequency interferometry

“…Figure 3, left c shows the response of sensor 1 before (solid blue line) and after (dashed green line) the displacement of the transducer. The measured time delay between the responses was 0.425μs which implies speed of sound of v~1494m/s, in agreement with the known values of speed of sound in water 10 . Next we tested the response of the sensor to sinusoidal excitations.…”

“…The second approach is based on two-arms interferometers where one of the arms (i.e. the sensing arm) is exposed to the acoustic wave 10 . This leads to phase variations in the sensing arm which are translated into intensity fluctuations at the detector output.…”

An optimized ultrasound detector for photoacoustic breast tomography

“…The sensitivity of this system was reported to be 1.66 mV/Pa at 1.5 MHz, the minimum detectable pressure (MDP) was not reported. 11 However, for some earlier versions the MDP values have been presented including measured 21 and estimated using only the thermal noise generated by the detector capacitance according to the Nyquist law. 19,22 The Twente photoacoustic mammoscope (PAM) has been previously developed in our group in 2004.…”

Near-Infrared Fluorescence Imaging and Spectroscopy in Random Media and Tissues

“…Optical detectors utilizing interferometric techniques [43,[53][54][55], oblique-incidence reflectance [56], microring resonators [57], fiber-optic lines [58,59], and laser beam deflection [60,61] can also be applied to detect ultrawideband optoacoustic signals. In addition to ultrawideband sensitivity, there are three main advantages of optical detection: (1) possibility for remote (noncontact) optoacoustic detection; (2) small finite size of the virtual detectors enabled by the tightly focused laser beam, which in turn yields high lateral resolution; and (3) possibility of avoiding acoustic diffraction and wavefront distortion in the handheld probes operating in the backward mode [62].…”