Optical element having wavelength selectivity

摘要

An optical element having a wavelength selectivity, which is easy to manufacture and reduces the manufacturing cost. The optical element comprises a light guide plate (22) having opposing two end faces (22a, 22b), and a multilayered film filter (23) formed on at least one of the opposing two end faces of the light guide plate. The multilayered film filter includes high-refractive-index dielectric layers and low-refractive-index dielectric layers laminated alternately and its thickness continuously changes in accordance with a position of the associated end face of the light guide plate. The center wavelength of transmitted light from the multilayered film filter differs in accordance with the position of the end face of the light guide plate. In a case where mixed light is input to the multilayered film filter from individual lenses via the light guide plate, the mixed light is separated to lights of different center wavelengths by the multilayered film filter that has different thicknesses.