diffract nearly all the quantity of the incident laser beam the diffraction optics portion 21 is configured to have a depth ranging from 600 nm to 700 nm and a pitch ranging from 0 020 mm to 0 340 mm wherein the depth and the pitch are changed in the radial direction in such a manner that the pitch becomes smaller and the depth becomes narrower in the direction from the center to the outer periphery of the objective lens 14 fig5 a to 5 c and fig6 a to 6 e are configuration views showing a state of manufacturing the objective lens 14 a process of manufacturing the objective lens 14 called a replica process will be described in detail with reference to fig5 a to 5 c and fig6 a to 6 e the process of manufacturing the objective lens 14 is generally divided into a process of manufacturing the geometrical optics portion 20 and a process of manufacturing the diffraction optics portion 21 first the process of manufacturing the geometrical optics portion 20 will be described with reference to fig5 a to 5 c fig5 a shows a die 30 composed of an upper die 31 and a lower die 32 between.