Abstract: A photoacoustic probe head (200a, 200b) is disclosed. The probe head (200a, 200b) comprises: a Fabry Perot acoustic sensor (202), an interrogation interface (A), an excitation input (B) and a two-axis mirror (204). The Fabry Perot acoustic sensor (200a, 200b) is operable to reflect an optical interrogation beam to create a reflected interrogation beam and to modulate the reflected interrogation beam in response to an acoustic signal at the acoustic sensor (202). The interrogation interface (A) is configured to receive an interrogation beam, and to receive the reflected interrogation beam from the acoustic sensor (202). The excitation input (B) is configured to receive an excitation beam for generating an acoustic field in a sample adjacent to the acoustic sensor (202). The two axis mirror (240) is configured to scan the interrogation beam between different locations of the acoustic sensor (202).