Mid-infrared optical coherence tomography with MHz axial line rate for real-time non-destructive testing

Fuente: arXiv
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Main Authors: Yagi, Satoko, Nakamura, Takuma, Hashimoto, Kazuki, Kawano, Shotaro, Ideguchi, Takuro
Format: Preprint
Published: 2023
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author Yagi, Satoko
Nakamura, Takuma
Hashimoto, Kazuki
Kawano, Shotaro
Ideguchi, Takuro
author_facet Yagi, Satoko
Nakamura, Takuma
Hashimoto, Kazuki
Kawano, Shotaro
Ideguchi, Takuro
contents Non-destructive testing (NDT) is crucial for ensuring product quality and safety across various industries. Conventional methods such as ultrasonic, terahertz, and X-ray imaging have limitations in terms of probe-contact requirement, depth resolution, or radiation risks. Optical coherence tomography (OCT) is a promising alternative to solve these limitations, but it suffers from strong scattering, limiting its penetration depth. Recently, OCT in the mid-infrared (MIR) spectral region has attracted attention with a significantly lower scattering rate than in the near-infrared region. However, the highest reported A-scan rate of MIR-OCT has been 3 kHz, which requires long data acquisition time to take an image, unsatisfying industrial demands for real-time diagnosis. Here, we present a high-speed MIR-OCT system operating in the 3-4 um region that employs the swept-source OCT technique based on time-stretch infrared spectroscopy. By integrating a broadband femtosecond MIR pulsed laser operating at a repetition rate of 50 MHz, we achieved an A-scan rate of 1 MHz with an axial resolution of 11.6 um and a sensitivity of 55 dB. As a proof-of-concept demonstration, we imaged the surface of substrates covered by highly scattering paint coatings. The demonstrated A-scan rate surpasses previous state-of-the-art by more than two orders of magnitude, paving the way for real-time NDT of industrial products, cultural assets, and structures.
format Preprint
id arxiv_https___arxiv_org_abs_2312_02408
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Mid-infrared optical coherence tomography with MHz axial line rate for real-time non-destructive testing
Yagi, Satoko
Nakamura, Takuma
Hashimoto, Kazuki
Kawano, Shotaro
Ideguchi, Takuro
Optics
Instrumentation and Detectors
Non-destructive testing (NDT) is crucial for ensuring product quality and safety across various industries. Conventional methods such as ultrasonic, terahertz, and X-ray imaging have limitations in terms of probe-contact requirement, depth resolution, or radiation risks. Optical coherence tomography (OCT) is a promising alternative to solve these limitations, but it suffers from strong scattering, limiting its penetration depth. Recently, OCT in the mid-infrared (MIR) spectral region has attracted attention with a significantly lower scattering rate than in the near-infrared region. However, the highest reported A-scan rate of MIR-OCT has been 3 kHz, which requires long data acquisition time to take an image, unsatisfying industrial demands for real-time diagnosis. Here, we present a high-speed MIR-OCT system operating in the 3-4 um region that employs the swept-source OCT technique based on time-stretch infrared spectroscopy. By integrating a broadband femtosecond MIR pulsed laser operating at a repetition rate of 50 MHz, we achieved an A-scan rate of 1 MHz with an axial resolution of 11.6 um and a sensitivity of 55 dB. As a proof-of-concept demonstration, we imaged the surface of substrates covered by highly scattering paint coatings. The demonstrated A-scan rate surpasses previous state-of-the-art by more than two orders of magnitude, paving the way for real-time NDT of industrial products, cultural assets, and structures.
title Mid-infrared optical coherence tomography with MHz axial line rate for real-time non-destructive testing
topic Optics
Instrumentation and Detectors
url https://arxiv.org/abs/2312.02408