Noncontact photoacoustic imaging achieved by using a low-coherence interferometer as the acoustic detector

We report on a noncontact photoacoustic imaging (PAI) technique in which a low-coherence interferometer [(LCI), optical coherence tomography (OCT) hardware] is utilized as the acoustic detector. A synchronization approach is used to lock the LCI system at its highly sensitive region for photoacoustic detection. The technique is experimentally verified by the imaging of a scattering phantom embedded with hairs and the blood vessels within a mouse ear in vitro. The system's axial and lateral resolutions are evaluated at 60 and 30 μm, respectively. The experimental results indicate that PAI in a noncontact detection mode is possible with high resolution and high bandwidth. The proposed approach lends itself to a natural integration of PAI with OCT, rather than a combination of two separate and independent systems.