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Author: Murat Yildirim
Requested Type: Either Oral or Poster
Submitted: 2015-04-28 11:16:12

Co-authors: N.Durr, A. Ben-Yakar

Contact Info:
The University of Texas at Austin
204 East Dean Keeton Street ET
Austin, Texas   78712

Abstract Text:
The growing interest in performing high-resolution, deep tissue imaging has galvanized the use of longer excitation wavelengths and three-photon based techniques in nonlinear imaging modalities. Since the imaging depth of 3-4 scattering lengths achievable with two-photon microscopy (TPM) at near infrared wavelengths would be insufficient to provide feedback during precise vocal fold microsurgery, we turned our attention to a three-photon based nonlinear imaging modality with a longer excitation wavelength to image deeper into the tissue. This study evaluates the improvement in maximum imaging depth with third-harmonic generation (THG) microscopy compared to TPM using a turnkey femtosecond fiber laser. Our experimental, analytical, and Monte-Carlo simulation results revealed that THG improved maximum imaging depths significantly from 140 µm to 420 µm in a highly scattered medium. Since tissue absorption length becomes substantial at the excitation wavelength of 1552 nm, we assessed the tissue thermal damage during imaging by obtaining the depth-resolved temperature distribution through a numerical simulation incorporating an experimentally obtained thermal relaxation time (τ). Hence, using 1552 nm as an illumination wavelength with effective thermal management proves to be a powerful deep imaging modality for highly scattering tissues such as scarred vocal folds.