Miniature multimodal endoscopic probe based on double-clad fiber

Optical coherence tomography (OCT) can obtain light scattering properties with a high resolution, while photoacoustic imaging (PAI) is ideal for mapping optical absorbers in biological tissues, and ultrasound (US) could penetrate deeply into tissues and provide elastically structural information. It is attractive and challenging to integrate these three imaging modalities into a miniature probe, through which, both optical absorption and scattering information of tissues as well as deep-tissue structure can be obtained. Here, we present a novel side-view probe integrating PAI, OCT and US imaging based on double-clad fiber which is used as a common optical path for PAI (light delivery) and OCT (light delivery/detection), and a 40 MHz unfocused ultrasound transducer for PAI (photoacoustic detection) and US (ultrasound transmission/receiving) with an overall diameter of 1.0 mm. Experiments were conducted to demonstrate the capabilities of the integrated multimodal imaging probe, which is suitable for endoscopic imaging and intravascular imaging.