Application Cases

Experimental Name: Acceleration Sensitivity and Directivity Testing of Co-Vibrational Triaxial Fiber-Optic Vector Hydrophones

Research Direction:
Exploring structural design and performance optimization methods for co-vibrational triaxial fiber-optic vector hydrophones. The study focuses on improving their acceleration sensitivity and directivity to meet engineering requirements for underwater acoustic signal detection. The research is divided into two core parts: first, using finite element simulation methods to analyze the coupling effects of elastomer geometric parameters (length, spherical shell outer diameter, fiber winding layers) on resonant frequency, acoustic pressure sensitivity, and acceleration sensitivity, establishing a parameter optimization model to balance sensitivity and frequency response characteristics; second, validating the design performance through acoustic water tank experiments, with emphasis on the constraining effect of the triaxial orthogonal suspension system on vibration transmission of the vector hydrophone, and quantitatively evaluating its acceleration sensitivity (stability within the 100 Hz–1 kHz frequency band) and directivity (symmetry of the "figure-8" pattern and sidelobe suppression capability) in practical performance, ultimately forming a miniaturized and high-consistency engineering packaging solution.

Experimental Objective:
To investigate the effects of elastomer geometric parameters (length, outer diameter, fiber layers) on the acceleration sensitivity and resonant frequency of fiber-optic vector hydrophones, as well as their optimization effects on wideband sensitivity stability (100 Hz–1 kHz) and high directivity, providing experimental support for underwater acoustic signal detection engineering applications.

Testing Equipment:
Low-frequency transducer, high-frequency transducer, ATA-L8B hydroacoustic power amplifier, standard acoustic pressure hydrophone, charge amplifier, oscilloscope, signal generator, demodulation board, etc.

Experimental Procedure:
In the acoustic water tank, the fiber-optic vector hydrophone (Φ100 mm) was fixed using a triaxial rubber band suspension system. Excitation signals in the 100 Hz–1 kHz range were generated by a standard piezoelectric hydrophone and the ATA-L8B power amplifier to calculate acceleration sensitivity. For directivity testing, low-frequency/high-frequency transducers were used as acoustic sources, and the hydrophone was rotated in 10° increments using a triaxial rotary table. The X/Y/Z triaxial acoustic pressure responses were recorded using a charge amplifier and an oscilloscope. Polar coordinate algorithms were employed to plot "figure-8" directivity patterns, and spectral analysis was used to extract main lobe suppression ratios (>25 dB) and sensitivity fluctuation ranges (±1.5 dB). Finally, a mapping relationship between elastomer parameters (length 16–25 mm, outer diameter 80–100 mm) and performance indicators was established.

Figure 1: Schematic Diagram of the Interferometric Fiber-Optic Hydrophone

Experimental Results:
Under the optimized configuration with an elastomer length of 25 mm, the simulated acceleration sensitivity of the co-vibrational triaxial fiber-optic vector hydrophone reached 42.79 dB re 1 rad/g, with an average measured sensitivity of 43.5 dB re 1 rad/g in the 100 Hz–1 kHz frequency band and sensitivity fluctuations controlled within ±1.5 dB, meeting the design targets. When the elastomer length was reduced to 16 mm, the acceleration sensitivity decreased to 37.68 dB re 1 rad/g, but the resonant frequency increased from 1690 Hz to 2080 Hz (the measured value was 8.5% higher than the simulation prediction), revealing a negative correlation between sensitivity and resonant frequency. In directivity testing, the X/Y/Z axial directivities under the triaxial orthogonal suspension system reached 27.2 dB, 26.7 dB, and 26.2 dB, respectively, with a main lobe suppression ratio of 26 dB and sidelobe energy attenuation >15 dB. The directivity patterns exhibited a typical "figure-8" symmetric distribution (amplitude deviation < ±1.2 dB), validating the effectiveness of the mass block-elastomer decoupling design. Further analysis showed that when the elastomer length was reduced from 25 mm to 16 mm, the acoustic pressure sensitivity linearly decreased from –134.5 dB to –138.8 dB (a reduction of 4.3 dB), while the resonant frequency increased by 23.1%, with an error of <5% compared to the finite element simulation results. This demonstrates the significant regulatory effect of elastomer geometric parameters on acoustic pressure sensitivity and frequency response. Ultimately, the experiment verified the synergistic optimization of the hydrophone in acceleration sensitivity (≥40 dB), directivity (>25 dB), and frequency band stability, providing a reliable engineering design basis for wideband, high-precision underwater acoustic signal detection.

Figure 2: Image of the Vector Hydrophone Suspension System

Figure 3: X, Y, Z Axial Acceleration Sensitivity

Figure 4: X, Y, Z Axial Directivity Patterns

Product Recommendation: ATA-L Series Hydroacoustic Power Amplifier

Figure: ATA-L Series Hydroacoustic Power Amplifier Specifications and Parameters

This document is compiled and published by Aigtek Antai Electronics. For more case studies and product details, please stay tuned. Xi'an Aigtek Antai Electronics has become a large-scale instrument and equipment supplier with a wide range of products in the industry. All demo units are available for free trial.