P5F-2 Improved Fiber Optic Hydrophone Sensors

Gopinath, R; Srinivasan, Karthik K.; Umchid, Sumet; Bansal, Lalitkumar; Daryoush, A.S.; Lewin, Peter A.; El-Sherif, Mahmoud A.

doi:10.1109/ultsym.2007.583

Cited by 4 publications

(9 citation statements)

References 10 publications

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“…The index of refraction of water depends on the acoustic pressure [11] and any incident acoustic pressure modulates the index of refraction of water, which in turn changes the amount of Fresnel back-reflected light intensity. The numerical analysis using simplified transmission line model as well as initial Finite Element Method has indicated that the gold coated down-tapered fibers provide a 15 dB improvement in sensitivity over that of the uncoated straight cleaved fibers [12]. In this paper, we present experimental results of sensitivity performance of three samples each of uncoated straight cleaved fiber, uncoated down-tapered fiber and gold coated straight cleaved fiber sensors.…”

Section: Optical Hydrophone Sensing Approachmentioning

confidence: 99%

“…This arrangement was crucial in order to perform a simultaneous measurement of all the fiber sensor samples and compare the sensitivity performance of the fiber optic hydrophone with that of the needle hydrophone under the same environmental and acoustic conditions. The fiber samples were fabricated as per the procedure mentioned in [12], where a gold coating for 20 second corresponds to the film thickness of around 100nm-150nm while for a 5 second gold coating; the thin film thickness is around 30nm. Gold coated fiber sample#1 and #2 were 5 second coating samples, while sample #3 was a 20 second coating sample.…”

Section: Optical Hydrophone Sensing Approachmentioning

confidence: 99%

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Broadband fiber optic hydrophone sensors for sub-millimeter ultrasound resolutions

Gopinath

Arora

Gandhi

et al. 2008

2008 International Topical Meeting on Microwave Photonics Jointly Held With the 2008 Asia-Pacific Microwave Photonics Conferenc

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Broadband fiber optic hydrophone probes are an attractive solution for characterization of ultrasound fields with sub-millimeter resolution up to 100MHz frequency range without need for complicated spatial averaging corrections. In this work, optical hydrophone sensors based on single mode straightcleaved fibers and down-tapered coated fibers with sensitive dimensions of less than 10μm have been reported. Thinly gold coated optical fiber sensors demonstrated a higher sensitivity and bandwidth performance than straight cleaved uncoated and down-tapered uncoated. The statistical analysis clearly indicates that the gold coated fibers with thickness of 30 nm provide a 26 dB improvement in sensitivity over that of the uncoated straight cleaved fibers, raising the overall sensitivity of the fiber optic hydrophone sensor to a value of -245 dB re 1V /μPa (unprecedented 0.56 V/ MPa). Broadband testing of these sensors with a 10MHz acoustic tone burst further indicates that the bandwidth of gold coated fiber sensor is as high as 60 MHz. Amplified optical source intensity noise limits the current intensity detection system up to 60MHz.

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Section: Optical Hydrophone Sensing Approachmentioning

confidence: 99%

Section: Optical Hydrophone Sensing Approachmentioning

confidence: 99%

Broadband fiber optic hydrophone sensors for sub-millimeter ultrasound resolutions

Gopinath

Arora

Gandhi

et al. 2008

2008 International Topical Meeting on Microwave Photonics Jointly Held With the 2008 Asia-Pacific Microwave Photonics Conferenc

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“…As already noted, beyond 60 MHz no independent verification of the data was available. With the calibration technique developed and verified, current research efforts are focused on further improvement of the sensitivity of the FO hydrophone probe [15] and verification of its uniform sensitivity response up to 100 MHz.…”

Section: Discussionmentioning

confidence: 99%

“…Such aperture is adequate for acoustic field measurements in the frequency range up to about 75 MHz without the need for spatial averaging correction. The optic measurement arrangement used in this work is discussed in details in a companion paper [15] (somewhere in this volume).…”

Section: Acousto-optic Measurements: Fiber Optic Hydrophone Probementioning

confidence: 99%

P4E-3 100 MHz Sub-Millimeter Size Fiber Optic Pressure Sensors: Luxury or Necessity?

Umchid

Gopinath²,

Srinivasan³

et al. 2007

2007 IEEE Ultrasonics Symposium Proceedings

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The primary objective of this research was to develop and optimize the calibration techniques for ultrasonic hydrophone probes in acoustic field measurements up to 100 MHz. Dependable, 100 MHz calibration method was necessary to examine behavior of the sub-millimeter fiber optic (FO) sensor and assess the need for such a sensor as an alternative tool for high frequency characterization of ultrasound fields. Also of interest was to investigate the feasibility of using FO probes in high intensity fields such as those employed in HIFU (High Intensity Focused Ultrasound) applications. The innovative elements of this research include implementation of a prototype FO sensor with an active diameter of about 10 µm that exhibits uniform frequency range and does not require any spatial averaging correction procedure up to about 75 MHz. The sensor is also sufficiently robust to measure fields generated by HIFU transducers. Accordingly, to test the FO probe behavior a novel 100 MHz bandwidth calibration technique was developed. This technique provided the sensitivity of conventional, finite aperture piezoelectric hydrophone probes as a virtually continuous function of frequency and allowed the verification of the uniformity of the FO sensor frequency response. As anticipated, the overall uncertainty of the calibration was dependent on frequency and determined initially to be about ±12% up to 40 MHz, ±20% up to 60 MHz and ±25% up to 100 MHz. Comparison of these data with those obtained from an independent laboratory is presented and a possibility of using the FO sensor as a reference tool to determine the phase response of finite aperture hydrophones is briefly discussed. Finally, the attempt is made to answer the question posed in the title. The outcome of this research indicates that once fully developed and calibrated, the combined acousto-optic system will form an important breakthrough in acoustic measurements of both diagnostic and therapeutic fields.

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“…Three unique acoustic methods (Time Delay Spectrometry (TDS) [10, 11], Time Gated Frequency Analysis (TGFA) [12] and semi-empirical nonlinear propagation model [13]) have been combined to determine the frequency dependent sensitivity of the finite aperture hydrophone probes and the frequency response of the 10 μm diameter FO prototype [14-16]. The application of TDS and TGFA equivalent technique in evaluation of the piezopolymer membrane hydrophone frequency response was independently reported in [17].…”

Section: Methodsmentioning

confidence: 99%

Development of calibration techniques for ultrasonic hydrophone probes in the frequency range from 1 to 100MHz

et al. 2009

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The primary objective of this work was to develop and optimize the calibration techniques for ultrasonic hydrophone probes used in acoustic field measurements up to 100 MHz. A dependable, 100 MHz calibration method was necessary to examine the behavior of a sub-millimeter spatial resolution fiber optic (FO) sensor and assess the need for such a sensor as an alternative tool for high frequency characterization of ultrasound fields. Also, it was of interest to investigate the feasibility of using FO probes in high intensity fields such as those employed in HIFU (High Intensity Focused Ultrasound) applications. In addition to the development and validation of a novel, 100 MHz calibration technique the innovative elements of this research include implementation and testing of a prototype FO sensor with an active diameter of about 10 μm that exhibits uniform sensitivity over the considered frequency range and does not require any spatial averaging corrections up to about 75 MHz. The results of the calibration measurements are presented and it is shown that the optimized calibration technique allows the sensitivity of the hydrophone probes to be determined as a virtually continuous function of frequency and is also well suited to verify the uniformity of the FO sensor frequency response. As anticipated, the overall uncertainty of the calibration was dependent on frequency and determined to be about ±12% (±1 dB) up to 40 MHz, ±20% (±1.5 dB) from 40 to 60 MHz and ±25% (±2 dB) from 60 to 100 MHz. The outcome of this research indicates that once fully developed and calibrated, the combined acousto-optic system will constitute a universal reference tool in the wide, 100 MHz bandwidth.

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P5F-2 Improved Fiber Optic Hydrophone Sensors

Cited by 4 publications

References 10 publications

Broadband fiber optic hydrophone sensors for sub-millimeter ultrasound resolutions

Broadband fiber optic hydrophone sensors for sub-millimeter ultrasound resolutions

P4E-3 100 MHz Sub-Millimeter Size Fiber Optic Pressure Sensors: Luxury or Necessity?

Development of calibration techniques for ultrasonic hydrophone probes in the frequency range from 1 to 100MHz

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