In this work we present the evaluation results of our 3D sonar camera system. The system consists of a matrix antenna array with 1024 single transducer elements and our in house developed DiPhAS sonar beamformer - a 128 channel FPGA-based beamforming system with a 1:8 multiplexing device for each channel. The system is designed to be applicable to ROV and AUV systems for real-time volumetric imaging in a deep sea environment. Defocused excitation of the transducer array is used to achieve a sound field opening angle of up to 40° in lateral and elevational direction. The antenna's sound field can be adjusted electronically in order to increase either the imaged area or the image contrast in a specific area of interest. Different filter algorithms working on a raw data basis have been implemented in order to suppress image artifacts which occur during the reconstruction process. Measurements on different phantoms have been performed in order to prove the real-time imaging as well as spatial resolution capabilities of the camera system

We present the newest application specific version of our beamformer platform “DiPhAS” that provides 256 parallel channels both for generation of ultrasound signals as well as digitalization of returned echos. Using ultrasound transducers with lots of elements requires high channel count electronics. Applications for such systems range from functional ultrafast imaging using high element count linear array transducers for imaging of a large field of view to real time volumetric imaging with matrix array transducers. To perform volumetric transmit beamforming with matrix transducers, lots of these matrix elements have to be controlled individually. Furthermore, many elements need to be excited in order to compensate for the small active element size and provide a sufficient overall active footprint to generate enough acoustic power for imaging with adequate SNR. The system is set up based on our platform concept with the common ultrasound research device components: mainboard, power supply, application-specific new front ends integrating 16 channels on each PCB and device software. Using 16 front ends results in a total channel count of 256. The new front ends are based on our existing 8 channel front end technology and share the same concepts with doubled channel count for both transmission and reception. The system generates transmit sequences with voltages up to 150 Vpp and digitizes with a sampling rate of up to 80 MHz. The beamformer implements the control for additional external multiplexers in the transducer probe. This has been tested with an external transducer matrix array and can be used to connect to our custom 1024 elements matrix array (32×32 elements) with a 1:4 multiplexer integrated into the probe head. Received data can be accessed as single element channel data of all 256 channels in parallel and transferred to a PC via PCI-Express. Beamforming can be done on a massively parallel computing graphics processor (GPU). The used software includes standard applications for measurements and interfaces for Matlab, C++ and C#. It is used to process, analyze and visualize data from the beamformer. This system will be scalable to an even higher channel count by connecting several beamformers to a single PC using multiple PCI-Express connections and additional synchronization over all single beamformer electronics. It is the basis of our 3D/4D ultrasound research system connected to our matrix arrays developed in-house

Object recognition, advanced distance measurements and other inspection scenarios have an increasing demand in versatile airborne ultrasonic phased arrays for acoustic scanning without moving parts. Based on cellular polymer film with high piezoelectric effect we have realized an array structure with a pitch of 0.5 mm and element length of 10 mm. The working frequency of the material was measured to 250 kHz. From pointspread simulation with the small ratio of pitch/wavelength of 0.35 we could expect good beam steering and focusing characteristics. A first test array was realized and characterized. There was good agreement between measurement results and simulations. Additionally a low frequency electronic beamformer system was developed for generating the first B-image of an airborne phased array. Measurements showed that cellular polymer is a well suitable material for airborne applications. It can easily be structured to the desired shape. It allows especially the realization of Phased Arrays for applications like surface or profile measurement, access control, attendance check, robot guidance etc.. New airborne array types like linear, phased, curved or circular arrays are now possible. Also single element transducers with varying apertures (rectangular, oval), shaped apertures (focusing (line-or point-focusing), defocusing) or combinations of both are possible.

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