Elimination of surface reflections in polarization imaging of superficial tissue

Polarization gating of light backscattered from tissue has been demonstrated to be an effective method of localizing light that has propagated within superficial tissue layers. A drawback of this approach is that light reflected from the surface of the tissue dominates the image. An optically flat plate and matching fluid applied to the tissue surface, combined with off-axis detection has previously been used to eliminate this problem. However this is often inappropriate or inconvenient for practical use. We demonstrate a method that combines images obtained with linearly and circularly polarized light to produce an image of light localized within the superficial layers that is free from surface reflections and does not require optically flat plates or matching fluid. This has the added benefit of enabling on-axis detection, thus simplifying systems.