| 摘要 |
PROBLEM TO BE SOLVED: To provide a transmission type diffraction element allowing easy manufacturing at low cost, and having high diffraction efficiency and low polarization dependency across an entire wavelength band of incoming light.SOLUTION: A transmission type diffraction element includes a transparent substrate and projections periodically formed on one surface of the transparent substrate and diffracts light entering the transparent substrate. The projections are formed by laminating a first layer, a second layer, a third layer, and a fourth layer from a side of the transparent substrate. The first layer and the third layer are made of a high refractive index material, and the second layer and the fourth layer are made of a low refractive index material having lower refractive index than the high refractive index material. |
