Transduction
Thursday 11th November 2010, 1100hrs–1200hrs
Chaired by Lynn Ewart Dual-Frequency Synthetic Aperture Sonar Array using Single-Crystal Technology Ms Poh Bee Tong, DSO National Laboratories, Singapore A dual-frequency (DF) synthetic aperture sonar (SAS) array has been designed and built based on PZN-PT single-crystal transducers. The array is designed to transmit and receive simultaneously in two frequency bands (15kHz and 150kHz) and has predicted SAS image resolutions of 13cm and 3cm in the low frequency (LF) and high frequency (HF) bands respectively. The purpose of using a DF system is to improve the probability of detecting and classifying small underwater objects, potentially including partially buried ones. This capability is particularly important in harbour and coastal areas where the seabed is muddy and small objects tend to be buried over time. Conventional side-scan and mine-hunting SONARS which work in the higher frequency regimes are typically unable to detect buried objects. Finally, the use of PZN-PT single-crystal piezoelectric transducer enables superior bandwidth and sensitivity over conventional PZT ceramics. In the LF band, the transducer has a Q-factor of 2.5 and is capable of a source level of up to 206dB (re 1uPa @ 1m). In the HF band, the transducer has a Q-factor of 5.0 and is capable of a source level up to 206dB (re 1uPa @ 1m). This paper discusses the concept, design and acoustic characterisation of this DF SAS array. High-performance PZN-PT Single Crystal Underwater Devices Dr. Leong-Chew Lim, Microfine Materials Technologies Pte Ltd, Singapore J. Jin Microfine Materials Technologies Pte Ltd, Singapore Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) single crystals exhibit superior electromechanical properties to state-of-the-art lead zirconate titanate (PZT) ceramics. Over the past five years, Microfine Materials Technologies has been developing a number of high performance sensors and actuators using this exciting material. Of the various devices developed, low-frequency (15 kHz) PZN-PT single crystal underwater (U/W) projectors of Tonpilz design displays unmatched performance in terms of compactness (<35 mm thickness), bandwidth, source level (without d.c. bias) and power efficiency. Current phase of development involves the design and fabrication of low-frequency broadband arrays for different applications as well as dual-frequency imaging arrays. PZN-PT shear and bending accelerometers have also been designed and tested. These single crystal accelerometers display exceptionally high sensitivity and are ideal for a wide range of demanding applications including high S/N ratio infrasonic (seismic) sensors for micro-tremor detection and classification. They can be readily packaged for U/W applications especially for compact U/W directional sensors and their arrays. In this paper, the design and performance of these new single crystal devices will be presented and discussed.
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Diamond Industry Patron
I got strong information on maritime capabilities, concepts and technology.
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Dr Christian Audoly
Head of Simulations, DCN/DSC, France
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