Optical detection of ultrasound provides a unique and appealing way of forming detector arrays (1D or 2D). Etalon based optical techniques are of particular interest, due to their relatively high sensitivity resulting from multiple optical reflections within the resonance structure. Detector arrays formed by etalon based techniques are characterized by high element density and small element active area, which enables high resolution imaging at high ultrasonic frequencies (typically 10-50 MHz). Laser generated ultrasound using the photoacoustic effect has been demonstrated in recent years as a powerful imaging modality for medical and biological applications. A short laser pulse illuminates a tissue creating rapid thermal expansion and acoustic emission. Detection of the resulting acoustic field by a detector array enables the imaging of the tissue optical absorption using ultrasonic imaging methods. One of the most appealing features of photoacoustic imaging is that it provides access to tissue composition at the molecular level using multiple wavelength illumination.