Fig. 1.

(a) Schematic of the console for the dual-modality photoacoustic (PA) and Optical Coherence Tomography (OCT) probe. PA light excitation delivery and OCT imaging are performed with an optical fiber within a commercial OCT catheter, and optical ultrasound reception is performed with a fiber optic ultrasound sensor. (b) A microscope image of the distal end of the probe, with a schematic overlay showing PA excitation light and corresponding PA ultrasound waves generated from an absorbing target within a vessel wall. The red spot is from a test laser at 632 nm. In this image, the polymer encapsulation of the OCT catheter was removed for clarity. PC: personal computer; DAQ: data acquisition; V_HF: high frequency voltage output; V_LF: low frequency voltage output. SMF: single-mode fiber; FO US sensor: fiber-optic ultrasound sensor.