Semi-resonant operation of a fiber-cantilever piezotube scanner for stable optical coherence tomography endoscope imaging

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.

Design of a handheld optical coherence microscopy endoscope

“…This design is still used in current research, 17,18 and there have been modifications to the mechanism of fiber scanning, including using electroactive polymers, 19 piezoactuators, 20, 21 thermoelectric actuators, 22 magnetic actuators, 23 and resonant scanning. 24,25 Other methods of forward scanning include counter-rotating GRIN lenses, 26,27 which have the smallest diameter at 1.65 mm, and MEMS 1-D 22, 28-30 and 2-D scanning. 31 All these designs used relatively low NA sample arm optics.…”

Design and control of a novel non-raster scan pattern for fast scanning probe microscopy

“…As mentioned in [24], the difference between the phases of the sine waves affects the pattern. However, for simplicity, we assume that the phase difference is zero.…”

“…The pattern period and shape is highly dependent on variable ω x − ω y [24], [25]. As mentioned in [24], the difference between the phases of the sine waves affects the pattern.…”

“…(4), k x and k y are natural numbers whose greatest common divisor is 1 (coprime numbers). In this way, the fraction fx fy is a rational number, which is selected in the following form to achieve further simplification compared to [24]:…”

Full-range Fourier domain optical coherence tomography imaging probe with a magnetic-driven resonant fiber cantilever

“…28,29 With the rapid development in OCT technologies, in recent years endoscopic OCT also underwent a transition from traditional low-speed time-domain mode to high-speed Fourier domain mode. 30,31 However, as in the regular bulky-scanner-based systems, the FD-OCT imaging probes can also suffer from a complexconjugate ghost image that could severely misguide the users. For some cases, a transparent window can be used to keep the image target within one side of the zero-delay position; 6 however, this method automatically sacrificed half of the image range and is not applicable for many other circumstances.…”