Patent ID: 7729227

Claim:
A diffractive element on which two wavelengths of light are incident from a light source, the diffractive element transmitting one of the two wavelengths of light to one type optical disc, the diffractive element splitting the other wavelength of light and emitting the split light to another type optical disc, the diffractive element comprising: a first member including a first resin and having a predetermined refractive index, and a second member having the same refractive index as the first member in the one wavelength of light and having a refractive index different from the first member in the other wavelength of light, wherein the first member and the second member are alternately arranged in a right-and-left direction with respect to an incidence direction of the two wavelengths of light, thereby constituting a diffraction grating, and wherein the second member includes organic matter having optical absorption in a predetermined wavelength range and a second resin to dissolve the organic matter at a molecular level so as to form the refractive index of the second member, wherein the organic matter is a dye, not a pigment.