Non-invasive bone densitometries using X-ray, e.g., DXA give precisely bone mineral densities (BMD), by which osteoporosis can be diagnosed, however, its usage are limited to in medical facilities, meaning inappropriate to routine screening for possible osteoporosis. Optical bone densitometry could be a promising way for osteoporosis screening with compactness and safety. In this study, a novel optical depth-resolved measurement method was proposed and its validity as a bone densitometry was tested by Monte Carlo simulation and model experiments. In this method, coherent light is emitted to a skin layer over bone tissue through an optical scattering modulator (OSM). By changing its thickness, the modulator changes continuously the scattering state of transmittance light between forward scattering able to penetrate deeper and isotropic scattering with a shallow penetration. With this optical penetration control, our method can give the optical information of bone, which correlates to BMD, separately from the interference by skin.
