Abstract
A forward-view optical coherence tomography (OCT) scanning catheter has been developed based on a fiber-cantilever piezotube scanner by using a semi-resonant scan strategy for a better scan performance. A compact endoscope catheter was fabricated by using a tubular piezoelectric actuator with quartered electrodes in combination with a resonant fiber cantilever. A cantilever weight was attached to the fiber cantilever to reduce the resonance frequency down to 63 Hz, well in the desirable range for Fourier-domain OCT. The resonant-cantilever scanner was driven at semi-resonance frequencies that were well out of the resonance peak but within a range of partial resonance. This driving strategy has been found to minimize the phase difference between the two scan axes for a better scan stability against environmental perturbations as well as for a driving simplicity. By driving the two axes at slightly different frequencies, a low-order Lissajous pattern has been obtained for a 2D area scan. 3D OCT images have been successfully acquired in an acquisition time of 1.56 seconds for a tomogram volume of 2.2 × 2.2 × 2.1 mm3. They were reconstructed without any scan calibration by extracting the scan timing from the image data. In addition, it has been found that the Lissajous scan strategy provides a means to compensate the relative axial motion of a sample for a correct imaged morphology.
Highlights
Optical coherence tomography (OCT) endoscopy is a powerful optical imaging modality useful for various areas of biomedical applications [1–11]
A forward-view optical coherence tomography (OCT) scanning catheter has been developed based on a fiber-cantilever piezotube scanner by using a semi-resonant scan strategy for a better scan performance
A compact endoscope catheter was fabricated by using a tubular piezoelectric actuator with quartered electrodes in combination with a resonant fiber cantilever
Summary
Optical coherence tomography (OCT) endoscopy is a powerful optical imaging modality useful for various areas of biomedical applications [1–11]. Others have developed beam scanners based on fiber cantilevers in which the focus is scanned directly by the in-plane motion of a fiber’s distal end [7–11] In this case, it is important to obtain a large scan amplitude required for the application while keeping the size of the actuator small. It has been experimentally observed that the weighted fiber cantilever exhibits a significant environmental sensitivity as a result of the resonance quality increased by the added oscillation mass This has necessitated the development of a different scan strategy which optimizes the developed scanning device so that it can be used in a harsh imaging condition. We have successfully demonstrated various advantages of our scan method by acquiring high-quality OCT images with enhanced stability, motion tolerance and the simplicity of no scan calibration This result can be generalized to other types of resonant scanners. In principle, can be operated in the semi-resonance regime utilizing the Lissajous scan when there are problems of environment sensitivity or scan nonlinearity
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