A bimodal endoscopic imager in a glass package

Abstract

We present the first endoscopic imaging probe that combines full-field white light video microscopy and 3D optical coherence tomography (OCT) in a single miniaturized instrument. Designed as an instrument for the working channels of conventional endoscopes, the presented system has dimensions of mm3 (l × w × h) and is an important step towards practical multi-modal optical biopsy systems for clinical use. The video modality has a sensor-limited resolution and a total field of view of 10 μm and 1.17 mm in diameter, respectively. The OCT modality works in a scanned imaging arrangement and provides 3D optical tomograms with a lateral resolution of 43.5 μm. An integrated tubular piezoelectric fiber scanner is used to perform en face scanning necessary for the 3D OCT measurements. The entire system is assembled and encapsulated within a glass package fabricated via 3D laser microstructuring, a technology which addresses the major issues of micro-optic assembly precision and biocompatibility.

Endoscopic optical coherence tomography angiography using a forward imaging piezo scanner probe

“…By continuously scaling the amplitude of the driving signals, a spiral scan pattern is obtained. To amplify the piezo displacement, the actuation frequency has to be close to the resonance frequency of the fiber . Figure B,D present a schematic depiction and image of the endoscopic probe head, respectively.…”

Comparison of optical coherence tomography angiography and narrow-band imaging using a bimodal endoscope

“…The lateral resolution of both modalities was measured using the knife-edge method and a resolution of 43.5 and 9.7 μm was determined for the OCT and WLI beam path, respectively. 23 Both channels are encapsulated in a glass package with outer dimensions of 15 × 2.4 × 3.3 mm 3 . The glass housing was manufactured by LightFab GmbH using a microstructuring process providing a precision of AE5 μm.…”

“…1(c). 23 For the acquisition of OCTA images, the piezoelectric tube was driven at an actuation frequency of 714 Hz at maximum voltage amplitude of 42.8 V to perform a spiral scan pattern with the fiber, and the circular FOV of the image was measured to be 1.146 mm in diameter. Before each measurement, a calibration of the piezo scanner was carried out to choose the best parameters for an optimum circular scan pattern.…”

Endoscopic Optical Imaging Technologies and Devices for Medical Purposes: State of the Art

“…By modulating the drive voltage in two pairs of electrodes, the desired scanning pattern from the fiber tip can be achieved. A large number of endoscopes are fabricated using this technique [84,91,[108][109][110].…”

“…The angular motion is fast with respect to the radial motion. The scanning pattern is smooth and is used in fiber-optic endoscopic scanners [3,110]. A higher frame rate can be achieved using a larger amplitude compared to a raster scanner.…”