High-throughput optical coherence tomography at 800 nm

Keisuke Goda,Omer Malik,Gilbert Fu,Alan Quach,Bahram Jalali,Ali Fard

doi:10.1364/oe.20.019612

Abstract

We report high-throughput optical coherence tomography (OCT) that offers 1,000 times higher axial scan rate than conventional OCT in the 800 nm spectral range. This is made possible by employing photonic time-stretch for chirping a pulse train and transforming it into a passive swept source. We demonstrate a record high axial scan rate of 90.9 MHz. To show the utility of our method, we also demonstrate real-time observation of laser ablation dynamics. Our high-throughput OCT is expected to be useful for industrial applications where the speed of conventional OCT falls short.

Highlights

Optical coherence tomography (OCT) has proven to be a valuable tool based on lowcoherence interferometry for micrometer-scale tomographic imaging of turbid media in a diverse range of applications [1,2]
We report high-throughput optical coherence tomography (OCT) that offers 1,000 times higher axial scan rate than conventional OCT in the 800 nm spectral range
This is made possible by employing photonic timestretch for chirping a pulse train and transforming it into a passive swept source

Summary

Introduction

Optical coherence tomography (OCT) has proven to be a valuable tool based on lowcoherence interferometry for micrometer-scale tomographic imaging of turbid media in a diverse range of applications [1,2]. For industrial applications, fast image acquisition is required for inspecting a large quantity of pieces in a short period of time as well as for imaging a large field of view [9,10,11] For these reasons, the frequency-domain OCT methods are preferred for field use as they provide higher scan rates and signal-to-noise ratio than the traditional time-domain method [2,3,4,5,6,7,8]. Different from the operation of conventional frequency-swept lasers, FDML drives an intra-cavity tunable band-pass filter at a period matched with the round-trip time of the cavity and overcomes the trade-off between the laser linewidth (i.e., axial range) and build-up time (i.e., sweep rate), producing axial scan rates as high as 5.2 MHz [4] Another technique that achieves MHz axial scan rates is Fourier-domain OCT with optical demultiplexers recently developed by Choi et al [5]. Our method is expected to be useful for industrial applications where the speed of conventional OCT falls short, such as material characterization, microfluidics, and manufacturing and process control

Schematic

Basic performance and theoretical analysis

Utility of high-throughput OCT

Summary