1 March 2010 Forty-five degree backscattering-mode nonlinear absorption imaging in turbid media
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J. of Biomedical Optics, 15(2), 026004 (2010). doi:10.1117/1.3368995
Abstract
Two-color nonlinear absorption imaging has been previously demonstrated with endogenous contrast of hemoglobin and melanin in turbid media using transmission-mode detection and a dual-laser technology approach. For clinical applications, it would be generally preferable to use backscattering mode detection and a simpler single-laser technology. We demonstrate that imaging in backscattering mode in turbid media using nonlinear absorption can be obtained with as little as 1-mW average power per beam with a single laser source. Images have been achieved with a detector receiving backscattered light at a 45-deg angle relative to the incoming beams' direction. We obtain images of capillary tube phantoms with resolution as high as 20 μm and penetration depth up to 0.9 mm for a 300-μm tube at SNR ~1 in calibrated scattering solutions. Simulation results of the backscattering and detection process using nonimaging optics are demonstrated. A Monte Carlo-based method shows that the nonlinear signal drops exponentially as the depth increases, which agrees well with our experimental results. Simulation also shows that with our current detection method, only 2% of the signal is typically collected with a 5-mm-radius detector.
Liping Cui, Wayne H. Knox, "Forty-five degree backscattering-mode nonlinear absorption imaging in turbid media," Journal of Biomedical Optics 15(2), 026004 (1 March 2010). http://dx.doi.org/10.1117/1.3368995
Submission: Received ; Accepted
JOURNAL ARTICLE
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KEYWORDS
Monte Carlo methods

Absorption

Nonlinear optics

Signal detection

Capillaries

Backscatter

Imaging systems

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