Other PAM systems require a fluid coupling medium for PA signal detection.46–49,51,61,63 This system uses air as a coupling medium and, thus, can be used to image samples that cannot normally be imaged using PAM, such as samples that would be altered or destroyed through contact with fluids, including powders or water-soluble dyes. There are other noncontact techniques based on optical interferometers such as Mach–Zehnder interferometer,57,58 low-coherence Michelson interferometer,59 and Fabry–Perot interferometer.61,63 These systems are typically complex, expensive, and difficult to integrate with another system. In most cases, the sample surface also required special treatment as the scattering and diffuse surface of the sample would affect the reflection of the probe light (sample arm) of the interferometer system and thereby its SNR. The Fabry–Perot sensor can also be used, but it is a contact technique as the sensor has to be placed in contact with the sample.57,62 Our sensor is inexpensive, simple, and easy to integrate with existing optical microscopes. The sensor can be used for opaque and highly scattering samples. As the microphone is located far from the laser beam direction, optical imaging techniques such as epi-fluorescence, confocal, Raman, phase contrast, bright, and dark field microscopy can be performed on the sample.