Optical phase conjugation for turbidity suppression in biological samples
Elastic optical scattering, the dominant light-interaction process in biological tissues, prevents tissues from being transparent. Although scattering may appear stochastic, it is in fact deterministic in nature. We show that, despite experimental imperfections, optical phase conjugation (λ = 532 nm) can force a transmitted light field to retrace its trajectory through a biological target and recover the original light field. For a 0.69-mm-thick chicken breast tissue section, we can enhance point-source light return by a factor of ~5 x 10^3 and achieve a light transmission enhancement factor of 3.8 within a collection angle of 29°. Additionally, we find that the reconstruction's quality, measured by the width of the reconstructed point source, is independent of tissue thickness (up to a thickness of 0.69 mm). This phenomenon may be used to enhance light transmission through tissue, enable measurement of small tissue movements, and form the basis of new tissue imaging techniques.
Additional Information© 2008 Macmillan Publishers Limited. Received 9 August 2007; Accepted 10 December 2007; Published online 27 January 2008. This work was supported by the National Science Foundation career award BES-0547657 and the Defense Advanced Research Projects Agency Center for Optofluidic Integration. Author contributions: Z.Y. was responsible for project planning, experimental work and data analysis. D.P. provided advice and loaned some equipment for the project. M.S.F. provided advice. C.Y. was responsible for administering the project, project planning, data analysis, and obtaining financial support for the project.
Accepted Version - nihms-111267.pdf