Extraction of near-axis scattered light for transillumination imaging

To suppress the scattering effect in transillumination imaging, a technique was developed to extract a near-axis scattered light (NASL) component from diffused light through a scattering medium. A diffuser is inserted between the light source and the incident surface of a scattering medium. We can extract the NASL component by subtracting the light intensity at the output surface with a diffuser from that without a diffuser. The principle to determine the subtraction weight was presented. In experiments using model phantoms of mammalian tissue, the proposed technique's effectiveness was verified. The cross-section of the propagation area of scattered light was confined to an 8% area around the optical axis of the incident light beam. The usefulness of this technique was demonstrated by transillumination imaging of the blood column through a diffuse medium.