was given by [PERSON] and [PERSON] [7] (1968). The relationship between the spatial distribution of heat sources and the temporal shape of the acoustic signal, excited by a laser pulse, was first theoretically analyzed in [8; 9]. The method for measuring the light absorption coefficient from the shape of a PA signal, excited therein, was first suggested and experimentally realized in [10; 11], and was later used in [12; 13; 14; 15; 16] for biological tissues. Considerable technological advances in computing, data acquisition, and processing, as well as progress in piezoelectric sensor array manufacturing, lead to rapid development of tomographic techniques employing PA effects. The two most developed and widely applied tomographic imaging modalities are various types of PA imaging (PAI) and laser ultrasonic imaging (LUI). The main difference between these two modalities is the location of light absorber. In PAI, the light is absorbed inside the investigated object and ultrasound waves carry information about the distribution of the light absorbers. Thus, the contrast in PAI is optical. In the case of LUI, the light is absorbed either in the dedicated external absorbing material (PA generator) or in the surface layer of the investigated object generating probe ultrasonic pulse. This probe pulse is scattered by the acoustic inhomogeneities inside the investigated object, and the scattered waves carry information about the distribution of acoustic inhomogeneities. Thus, the contrast in LUI is acoustic. Although there are various techniques that are used for conversion of wide-band acoustic waves (mechanical displacement) into electronic signals, including electromagnetic [17] and capacitive transducers [18], in this review, we focus on the two widely used ultrasound detection techniques [18]: piezoelectric transducers [13; 19; 20] and optical interferometers and deflectors [21; 22; 23; 24]. The non-contact nature of laser generation of ultrasound makes it attractive to develop fully non-contact (all-optical) PAI and laser ultrasonic (LU) evaluation systems employing both optical generation and optical detection of acoustic transients. Although optical sensors can possess ultrawide detection bandwidth [18], surface roughness strongly affects the sensitivity of optical detection, and overall system sensitivity is typically a few orders of magnitude smaller than that of contact wideband ultrasound sensors [24]. Therefore, the main attention is drawn, in this paper, to the piezoelectric detection of acoustic waves. The most sensitive acoustic detectors utilize resonance of physical dimensions and ultrasound waves to be detected. The product of sensitivity and the bandwidth is a constant defined by properties of the detector. Therefore, detection within a narrow frequency band is the most sensitive [25]. However, LU probe pulses, as well as PA ultrasonic transients, have intrinsic wide bandwidth that should be detected if a high spatial resolution is desired. In the traditional pulse-echo mode of ultrasound (US) imaging, array transducers (linear array, phased array, and curved array) have replaced single element transducers decades back. It helped US imaging devices to become real-time, portable, and handheld. Similarly, the PA community has also adopted array transducers (linear, semicircular, circular, and spherical array) to develop highspeed/real-time PA imaging [26; 27; 28; 29]. Medical imaging is continuously evolving following new medical technologies. The advances in medical imaging tools (X-ray computed tomography (X-ray CT), ultrasound (US), magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography, etc.) have led to better diagnosis and patient care [26; 30; 31; 32]. During the last decade, PAI has been evolving rapidly, from the laboratory to preclinical and clinical phases [33; 34; 35]. PAI is a three-dimensional (3D) hybrid imaging modality that combines the advantages of optical and acoustic imaging.