Astigmatism-corrected endoscopic imaging probe for optical coherence tomography using soft lithography

Abstract

In endoscopic optical coherence tomography, a transparent protective sheath is used to protect the optics and tissue. However, the sheath causes astigmatism, which degrades transverse resolution and signal-to-noise ratio due to the cylindrical lens effect. Generally used methods for correcting this astigmatism are complex, difficult to control precisely, high-cost, and increase the dimensions of the imaging probe. To overcome these problems, we have developed an astigmatism-corrected imaging probe with an epoxy window. The astigmatism is precisely and cost-effectively adjusted controlling the curvature radius of the epoxy window, which is produced by soft lithography. Using the fiber optic fusion splicing, the fabrication process is simple. The fabricated imaging probe is almost monolithic, so its diameter is similar to that of a standard single-mode fiber. We demonstrate its astigmatism-correcting performance using focal spot analysis, imaging micro-beads and a biological sample.

Liquid-shaped microlens for scalable production of ultrahigh-resolution optical coherence tomography microendoscope

“…3d-h and Materials and methods). It is noted that the source of astigmatism is derived from the cylindrical wall of the glass capillary or plastic sheath, which has different curvatures parallel and perpendicular to the endoscope axis 19,[36][37][38] . Compiling the simulated results indicated an optimal design region (Fig.…”

Comparison of micro-optic systems for close-focus microendoscopic applications

“…Previous work by other groups have mitigated the optical performance limitations of a GRIN singlet by placing additional optical elements in proximity to, or directly printed on, the GRIN element. For example, an epoxy window created via soft-lithography was used to correct for the effects of a GRIN-fiber based optical coherence tomography (OCT) probe 29 . 3D-printed surfaces are commonly used to create correction surfaces for GRIN-based systems, like in the case of a two-photon microscopy system 30 , leading us to the field of entirely 3D-printed lenses.…”

Deep learning-based image enhancement in optical coherence tomography by exploiting interference fringe

“…While hardware-based enhancement techniques require expensive high-performance lasers and/or additional optical components to improve OCT images 8 – 11 , software-based approaches can achieve such enhancement with only minimal modification to the underlying system. Conventional software-based studies have proposed spectral estimation 12 and spectrum - shaping 13 for enhancing resolution, and B-scan averaging 14 and filtering-based methods 15 – 17 for suppressing noise.…”