2 March 2015 The mid-infrared swept laser: life beyond OCT?
Author Affiliations +
Abstract
Near-infrared external cavity lasers with high tuning rates (“swept lasers”) have come to dominate the field of nearinfrared low-coherence imaging of biological tissues. Compared with time-domain OCT, swept-source OCT a) replaces slow mechanical scanning of a bulky reference mirror with much faster tuning of a laser cavity filter element and b) provides a ×N (N being the number of axial pixels per A-scan) speed advantage with no loss of SNR. We will argue that this striking speed advantage has not yet been fully exploited within biophotonics but will next make its effects felt in the mid-infrared. This transformation is likely to be driven by recent advances in external cavity quantum cascade lasers, which are the mid-IR counterpart to the OCT swept-source. These mid-IR sources are rapidly emerging in the area of infrared spectroscopy. By noting a direct analogy between time-domain OCT and Fourier Transform Infrared (FTIR) spectroscopy we show analytically and via simulations that the mid-IR swept laser can acquire an infrared spectrum ×N (N being the number of spectral data points) faster than an FTIR instrument, using identical detected flux levels and identical receiver noise. A prototype external cavity mid-IR swept laser is demonstrated, offering a comparatively low sweep rate of 400 Hz over 60 cm-1 with 2 cm-1 linewidth, but which provides evidence that sweep rates of over a 100 kHz should be readily achievable simply by speeding up the cavity tuning element. Translating the knowledge and experience gained in near-IR OCT into mid-IR source development may result in sources offering significant benefits in certain spectroscopic applications.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. T. D. Childs, D. T. D. Childs, R. A. Hogg, R. A. Hogg, D. G. Revin, D. G. Revin, Ihtesham U. Rehman, Ihtesham U. Rehman, J. W. Cockburn, J. W. Cockburn, S. J. Matcher, S. J. Matcher, } "The mid-infrared swept laser: life beyond OCT?", Proc. SPIE 9312, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIX, 931239 (2 March 2015); doi: 10.1117/12.2081872; https://doi.org/10.1117/12.2081872
PROCEEDINGS
4 PAGES


SHARE
Back to Top