Project Summary Optical coherence tomography (OCT) has revolutionized medical diagnostics by providing high- resolution morphological imaging. However, the early stages of many diseases occur before any morphological changes are detectable. To address this gap, the optical attenuation coefficient (OAC) has been identified as a promising contrast mechanism to enhance OCT’s diagnostic power. Despite its potential, traditional OCT struggles with precise OAC measurement due to multiple scattering and model fitting uncertainties. Our parent grant aims to overcome these challenges by developing beam offset OCT (BS-OCT), which promises accurate OAC quantification by analyzing the backscattered photon profile (BSPP). This project will create and validate high-quality tissue phantoms to support the BS-OCT technology, ensuring precise measurement capabilities before in vivo testing. We have two aims: Aim 1: Fabricate and test high-quality phantoms for OAC measurement validation. Aim 2: Create multi-layer tissue phantoms for retinal simulation and BS-OCT validation. The outcomes of this project will significantly advance OCT technology by providing robust validation tools for BS-OCT. These phantoms will not only support OCT but also benefit other imaging modalities, potentially becoming standard references for the broader imaging community. Detailed documentation will be disseminated via the NIST/NIBIB Imaging Phantom Lending Library.