Abstract: The present invention provides an apparatus for functional imaging of an object that is compact, sensitive, and provides real-time three-dimensional images. The apparatus includes a source of non-ultrasonic energy, where the source induces generation of ultrasonic waves within the object. The source can provide any type of non-ultrasonic energy, including but not limited to light, heat, microwaves, and other electromagnetic fields. Preferably, the source is a laser. The apparatus also includes a single capacitive micromachined ultrasonic transducer (CMUT) device or an array of CMUTs. In the case of a single CMUT element, it can be mechanically scanned to simulate an array of any geometry. Among the advantages of CMUTs are tremendous fabrication flexibility and a typically wider bandwidth. Transducer arrays with high operating frequencies and with nearly arbitrary geometries can be fabricated. A method of functional imaging using the apparatus is also provided.