Motion-immune digital refocusing of point-scanning optical coherence tomography with Lissajous scan

Shuichi Makita; Lida Zhu; Kensuke Oikawa; Yoshiaki Yasuno

doi:10.1117/12.2609797

7 March 2022 Motion-immune digital refocusing of point-scanning optical coherence tomography with Lissajous scan

Shuichi Makita, Lida Zhu, Kensuke Oikawa, Yoshiaki Yasuno

Proceedings Volume 11948, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVI; 119480F (2022) https://doi.org/10.1117/12.2609797
Event: SPIE BiOS, 2022, San Francisco, California, United States

Conference Poster

Abstract

Post-signal-processing techniques of refocusing and digital aberration correction of optical coherence tomography (OCT) restore the spatial resolution deteriorated by optical aberrations. In the case of in vivo biological tissues with Fourierdomain OCT, an ultrafast volumetric acquisition is required to avoid motion distortion. In point-scanning OCT, a fast scan is required, and the bulk phase shifts among surrounding A-lines should be corrected. A low duty cycle might be necessary to obtain the consistent en face image with a high-speed raster scan. Recently, we have demonstrated a Lissajous-patternbased probe beam scanning and motion correction algorithm. In this study, we demonstrate a Lissajous-cycle-wise (LCW) digital refocus algorithm. The algorithm of LCW digital refocus is based on a convolution operation with an inverse filter. The complex OCT signals sampled with a Lissajous cycle are going to be convolved with an inverse filter of defocus. The reconstruction from Lissajous data to the Cartesian coordinate assigns a Cartesian grid to each A-line. By merging A-lines of different cycles, blurring due to defocus perpendicular to the scanning trajectory is mitigated by other cycle data. The phantom experiment is applied for the proof of concept. A prototype 1-μm spectral-domain OCT system is used for experiments. The A-line rate is 92 kHz. The blurred image of a phantom by defocusing is sharpened by the LCW digital refocus process along with all directions in the en face plane. Although the restored resolution does not reach the diffraction limit, an ultrafast volumetric acquisition is not required when one Lissajous cycle is significantly faster than sample motion.

Conference Presentation

Citation Download Citation

Shuichi Makita, Lida Zhu, Kensuke Oikawa, and Yoshiaki Yasuno "Motion-immune digital refocusing of point-scanning optical coherence tomography with Lissajous scan", Proc. SPIE 11948, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVI, 119480F (7 March 2022); https://doi.org/10.1117/12.2609797

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