Four-channel spectral imaging in visible wavelength utilizing photonic crystal patterned wavelength filters

A four-channel spectral imaging system utilizing multilayer-type photonic crystal (PhC) is demonstrated. In order to check the feasibility of the system for the application to biomedical measurement in the future, we took hemoglobin as a test target. PhC-long wavelength pass filters (LPFs) were designed to function as a set of LPFs covering a part of the visible wavelength range where absorption peaks of hemoglobin exist. As a result of the preliminary imaging experiment of hemoglobin densities for a tissue phantom, we verified that the proposed system had an ability to visualize the hemoglobin distribution with the concentration range of ×1 to ×500. In addition, we confirmed the system was capable of acquiring relative blood density in real time.