We present a preclinical-grade, forward-viewing endomicroscope for in-contact optical coherence tomography (OCT) and optical coherence angiography (OCA) imaging through the working channel of a conventional cystoscope. Beam scanning is achieved with a fiber scanner driven by a tubular piezoelectric actuator. A focusing lens at the fiber tip helps engineering of the operation frequency within a compact probe length to avoid lateral undersampling. Microstructuring of fused silica through selective laser-induced etching was used for manufacturing a self-aligning housing for the probe head. The entire micro-optical system is assembled and encapsulated within a custom-developed sterilizable packaging with 4.5 mm outer diameter. The presented design and fabrication strategy can be used for any forward-viewing probe, independent of its imaging modalities. We demonstrate OCT imaging within a 2.1-mm diameter field of view at a transverse resolution of 19 μm and microvasculature visualization through OCA. The presented probe’s mechanical characteristics and optical performance make it particularly attractive for outpatient care use in the detection of tissue pathology inside the bladder. The presented fabrication methodology provides a reliable strategy for enabling preclinical trials with endoscopic imaging probes.
This work presents the design and implementation of an endoscopic probe for point-of-care diagnosis of bladder cancer, with an outer diameter of 4.5 mm that allows for in-vivo usage. This triple-modality device can deliver volumetric OCT images, optoacoustic tomograms, and single point Raman spectroscopy that target complementary biomarkers. The probe features a piezo-based fiber scanner, which delivers the illumination or excitation light for all modalities, with a maximum Field of View of 1.6 mm. The same path is used for light collection for OCT imaging. A separate fiber is used for detection of the Raman signals, while two additional fibers with microcavity tips sense the ultrasonic waves for optoacoustic tomography. A hyperchromatic micro-optical objective provides a working distance optimized for each modality. The probe housing is produced by selective laser-induced etching of fused silica.
This work discusses the design and implementation of a compact forward-looking OCT probe with clinical grade encapsulation that can be readily incorporated into endoscopic systems. Its optical performance makes it particularly attractive for outpatient care use in the optical detection of tissue pathologies inside of the bladder. The use of a tubular piezoelectric-based fiber scanner allows for forward-looking 3D imaging with a single fiber, which can be operated in a quasi-resonant regime to provide a large scanning range with relatively low driving voltages, while maintaining a small outer diameter. This configuration and the adjustable scanning rate of the fiber allow for not only high-resolution OCT images, but also the potential implementation of functional extensions like OCT Angiography. Commercially available focusing optics are used at the tip of the probe, which is designed for telecentric operation in contact with the tissue. The coupling parts, as well as the probe housing, are produced using selective laser-induced etching of fused silica, a 3D structuring approach that enables the creation of alignment and pinning features with micrometer precision. The use of this technology allows for finely tuned optical and mechanical designs, while facilitating the mounting and interconnection of components, providing a reliable assembly process.