GRIN lens rod based probe for endoscopic spectral domain optical coherence tomography with fast dynamic focus tracking

Tuqiang Xie,Zhongping Chen,David Mukai,Shuguang Guo,Matthew Brenner

doi:10.1364/oe.14.003238

Abstract

In this manuscript, a GRIN (gradient index) lens rod based probe for endoscopic spectral domain optical coherence tomography (OCT) with dynamic focus tracking is presented. Current endoscopic OCT systems have a fixed focal plane or working distance. In contrast, the focus of this endoscopic OCT probe can dynamically be adjusted at a high speed (500 mm/s) without changing reference arm length to obtain high quality OCT images for contact or non-contact tissue applications, or for areas of difficult access for probes. The dynamic focusing range of the probe can be from 0 to 7.5 mm without moving the probe itself. The imaging depth is 2.8 mm and the lateral scanning range is up to 2.7 mm or 4.5 mm (determined by the diameter of different GRIN lens rods). Three dimensional imaging can be performed using this system over an area of tissue corresponding to the GRIN lens surface. The experimental results demonstrate that this GRIN lens rod based OCT system can perform a high quality non-contact in vivo imaging. This rigid OCT probe is solid and can be adapted to safely access internal organs, to perform front or side view imaging with an imaging speed of 8 frames per second, with all moving parts proximal to the GRIN lens, and has great potential for use in extremely compact OCT endoscopes for in vivo imaging in both biological research and clinical applications.

Highlights

Optical coherence tomography (OCT) has been rapidly developed and widely used to image biological tissues as a new in vivo noninvasive morphological imaging technique [1, 2]
Current endoscopic optical coherence tomography (OCT) systems have a fixed focal plane or working distance. The focus of this endoscopic OCT probe can dynamically be adjusted at a high speed (500 mm/s) without changing reference arm length to obtain high quality OCT images for contact or non-contact tissue applications, or for areas of difficult access for probes
Three dimensional imaging can be performed using this system over an area of tissue corresponding to the GRIN lens surface

Summary

Introduction

Optical coherence tomography (OCT) has been rapidly developed and widely used to image biological tissues as a new in vivo noninvasive morphological imaging technique [1, 2]. Some organs such as liver and larynx may require non-contact imaging in certain applications Other tissues such as veins, intestine, cartilage, airway and colon may present curved or irregular surfaces, making it difficult or suboptimal to operate the entire probe at high speed while adjusting a fixed focal plane to encompass the entire axial scan range. In such cases the lateral resolution and the signal to noise ratio will decrease with increasing depth from the focal plane of the probe lens. A method for high speed dynamic focus tracking in endoscopic probes is critical for high quality tissue imaging in real time endoscopic OCT or optical coherence microscopy (OCM) systems, in particular, for accessing some internal organs

Methods

Results

Conclusion