Papers by Keyword: Hydrophone

Abstract: A novel transducer for megasonic cleaning of photomasks presents an approach that differs from previous configurations, and appears to have unique features for cleaning while minimizing damage. As the cleaning and damage processes are determined by the presence of cavitation, a thorough acoustic analysis was performed on the device, by using a calibrated hydrophone scanned at the photomask location, and a quartz photomask with embedded sensors.

Abstract: During construction and during exploitation operations of the offshore objectives occurs, inevitably, noise pollution in the marine environment. This paper presents a system for measuring underwater acoustic field. The mobile polygon is described, which is used in noise measurements for the determination of sea noise.

Abstract: Emerging ultrasonic and megasonic cleaning demands in various applications (solar cell, storage devices, wafer and mask cleaning, etc.) dictate the need to understand the acoustic cavitation under different operating conditions to optimize efficiency of cleaning and reduce damage. Major parameters that affect cavitation include frequency of the sound field, operating power of the transducer and the cleaning chemistry. Previous studies have reported the use of common techniques such as multi-bubble sonoluminescence [1] and sono-electrochemistry [2] to understand acoustic cavitation. The disadvantage with sonoluminescence technique is that it characterizes cavitation mainly in the bulk of the solution, which may not be pertinent to wafer cleaning applications where the interest is in understanding cavitation phenomena close to the wafer surface. Although, sono-electrochemical techniques employing microelectrode are capable of measuring cavitation in the vicinity of a solid surface, they are limited to measurements on an extremely small area due to the miniscule size (5-25 μm) of the electrode. In this context, hydrophone measurements offer significant benefit as they can be taken near a solid surface as well as on a relative large area (1-2 mm diameter) of the pressure sensitive tip.

Abstract: Sound pressure is an important parameter of marine background noise monitoring. A laser interferometric hydrophone is designed based on Michelson interferometry. By tracking compensation method, immunity from interference of the hydrophone is improved. Error analysis shows that the vibrating membrane is the main source of the sound pressure error, which can be eliminated to a certain extent by a vibrating membrane materials selection. Offshore data show that hydrophone pressure measurement of high precision, and with a good frequency response. By comparison with the theoretical model to some extent also verified the accuracy of data. In coastal waters, wind noise and ship radiate noise is the main noise source of marine ambient noise. Here, marine ambient noise spectrum of three wind speed were calculated, and with Kundsen curves were compared. Results show that measured data and Kundsen curve fitting is better. In addition, the measurement of vessel radiation noise is mainly concentrated in frequency range of 350~500Hz.

Abstract: In view of the existing of low frequency hydrophone in signal detection problems such as low sensitivity, frequency range is small, In this paper, application of PVDF piezoelectric film as sensitive material of low frequency hydrophone, use its advantages as fast response, high sensitivity, good mechanical properties, and so on [1], designed a kind of low frequency hydrophone, experiments are carried out to study the detection of low frequency signal. This paper introduces the structure, material and size of the hydrophone, and analyzes the experimental data. Experiments show that the sensor stability and high sensitivity, can effectively detect the low frequency acoustic wave in the water.

Abstract: This paper presents some results of finite element (FE) analysis performed for membrane-type piezoceramic transducer for underwater acoustics applications. We studied the miniaturized sensor with perforated holes in the active PZT membrane, intermediate, and protective plates. In this investigation an influence of the polyimide plate viscous damping, the membranes dimensions and the relative area of the perforated holes on the frequency response of sensitivity was studied for the broadening and flattening the operating frequency band. An optimization of these key parameters using the genetic algorithm working with the device’s FE model was demonstrated.

Abstract: In this paper, the basic theories and characteristics of distributed Bragg reflection (DBR) fiber laser and distributed feedback (DFB) fiber laser as hydrophone were described and analyzed; The interferometric demodulation technique of the underwater acoustic signals from fiber Bragg grating (FBG) hydrophone was discussed; And the theoretical experimental conclusions of the ultra-thin fiber Bragg grating hydrophone were introduced; Finally, the application in the torpedo homing field of the research on the ultra-thin fiber Bragg grating hydrophone were prospected.

Abstract: In order to eliminate unnecessary table-over-travel of a surface grinding machine, the authors previously developed an adaptive table-reciprocation-control system using a hydrophone. The system eliminated the over-travel and reduced grinding time by 20-40%. However, during the stage of the grinding-wheel approach to a workpiece the system did not work. In order to improve the efficiency and reliability of the system, a fluid-flow stabilizer and a new coolant-supply nozzle have been developed and their performances were experimentally investigated. By using these devices, the reciprocation-control system showed its capability even during the stage of the grinding-wheel approach and this ability improved the system efficiency and reliability.