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. While scattering may appear stochastic, it is in fact deterministic in nature. We show that, despite experimental imperfections, optical phase conjugation (lambda = 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 approximately 5x10(3) times and achieve a light transmission enhancement factor of 3.8 within a collection angle of 29 degrees . Additionally, we find that the reconstruction's quality, measured by the width of the reconstructed point source, is independent of tissue thickness (up to 0.69 mm thick). 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.