The Effect of the Shape and Location of the Light Source in Diffuse Reflectance Measurements

Optical measurements are fast and convenient mode to obtain information from human skin. However, the complicated interactions of light with skin may overwhelm our understanding of the measurements. Moreover, the high remittance from the surface of the skin may be often an obstacle for making measurements regarding deeper layers of skin. In this research, we have constructed a simulation model to show from which depths the remittance is coming from. Using this model we have studied the effects of light source shape and location to measure the remittance originating deeper. According to the model, the ring-shaped light source more than doubles the measurement depth, compared with the diffuse light. In fiber-based measurements, increase of the fiber separation increases the measurement depth.