Auto-focused virtual source imaging (AVSI) has been recently presented as an alternative method for synthetic aperture focusing through arbitrarily shaped interfaces with arrays. This paper extends the AVSI concept to the case of the total focusing method (TFM-AVSI) using several virtual receivers for each virtual source. This approach overcomes the known contrast limitation of AVSI, while preserving the advantage of performing synthetic focusing in the second medium only [no time-of-flight (TOF) calculations through the interface]. In contrast, equipment with more active channels must be used to digitalize the signals received by all the array elements after each focused emission. When compared with the conventional TFM, the proposed method reduces the processing complexity of the most time consuming task: TOF calculation in the presence of interfaces. This improvement could lead to more efficient real-time implementations of the TFM in non-destructive testing applications where water immersion or flexible wedges are used. In this paper, the mathematical formulation for the new method is given, accounting for the surface slope and the array angular sensitivity. Its performance is evaluated by numerical simulation, experimentally and compared with AVSI and the conventional TFM. It was found that the TFM-AVSI achieves the same resolution and contrast as that of the TFM, although it shows a wider blind zone below the interface due to focusing with normal incidence.

Phase Coherence Imaging was proposed in 2009 as a new adaptive beamforming method, based on measuring the instantaneous phase dispersion of the aperture data. Low phase dispersion is indicative of a focused reflector, while large phase dispersion is produced by out of focus reflectors, reverberations and the grained structure of some materials. Based on a phase dispersion metric, a coherence factor can be defined and used to weight the beamformer output, in such a way that focused reflectors are maintained (low phase dispersion), while side-lobes, grating-lobes, reverberations and grain noise are reduced (large phase dispersion). Besides increasing the image dynamic range by reducing the sidelobes and background noise, lateral resolution is simultaneously improved by reducing the main-lobe width.Several phase coherence factors have been defined, based on different dispersion metrics with different computational complexity and noise reduction levels. In particular, a realization based on the sign of the received signals (Sign Coherence Factor) allows implementing the method in real-time with very low hardware resources requirements. The coherence factor can be used to weight the beamformer output or as an image itself, with the property of representing reflectors with amplitudes independent of their reflectivity.

Plane Wave Imaging (PWI) has been recently proposed for fast ultrasound inspections in the Non-Destructive-Testing (NDT) field. By using a single (or a reduced number) of plane wave emissions and parallel beamforming in reception, frame rates of hundreds to thousands of images per second can be achieved without significant image quality losses with regard to the Total Focusing Method (TFM) or Phased Array (PA). This work addresses the problem of applying PWI in the presence of arbitrarily shaped interfaces, which is a common problem in NDT. First, the mathematical formulation for generating a plane wave inside a component of arbitrary geometry is given, and the characteristics of the resultant acoustic field are analyzed by simulation, showing plane wavefronts with non-uniform amplitude. Then, an imaging strategy is proposed, accounting for this amplitude effect. Finally, the proposed method is experimentally validated, and its application limits are discussed.

Photoacoustic (PA) imaging, by integrating optical and ultrasound (US) modalities, combines high spatial resolution with deep tissue penetration, making it a transformative tool in biomedical research. This review presents a comprehensive analysis of the current status of dual PA/US imaging technologies, emphasising their applications in preclinical research. It details advancements in light excitation strategies, including tomographic and microscopic modalities, innovations in pulsed laser and alternative light sources, and US instrumentation. The review further explores preclinical methodologies, encompassing dedicated instrumentation, signal processing, and data analysis techniques essential for PA/US systems. Key applications discussed include the visualisation of blood vessels, micro-circulation, and tissue perfusion; diagnosis and monitoring of inflammation; evaluation of infections, atherosclerosis, burn injuries, healing, and scar formation; assessment of liver and renal diseases; monitoring of epilepsy and neurodegenerative conditions; studies on brain disorders and preeclampsia; cell therapy monitoring; and tumour detection, staging, and recurrence monitoring. Challenges related to imaging depth, resolution, cost, and the translation of contrast agents to clinical practice are analysed, alongside advancements in high-speed acquisition, artificial intelligence-driven reconstruction, and innovative light-delivery methods. While clinical translation remains complex, this review underscores the crucial role of preclinical studies in unravelling fundamental biomedical questions and assessing novel imaging strategies. Ultimately, this review delves into the future trends of dual PA/US imaging, highlighting its potential to bridge preclinical discoveries with clinical applications and drive advances in diagnostics, therapeutic monitoring, and personalised medicine.

In this work, a novel hardware architecture for fast ultrasound imaging based on FPGA devices is proposed. A key difference over other approaches is the unlimited scalability in terms of active channels without performance losses. Acquisition and processing tasks share the same hardware, eliminating communication bottlenecks with smaller size and power losses. These features make this system suitable to implement the most demanding imaging applications, like 3D Phased Array, Total Focusing Method, Vector Doppler, Image Compounding, High Speed Part Scanning and advanced elastographic techniques. A single medium sized FPGA allows beamforming up to 200 scan lines simultaneously, which is enough to perform most of the above mentioned applications in strict real time