| 摘要 |
PURPOSE:To obtain an inexpensive optical head which can be mass-produced by making lattice optical elements into metallic display relief lattices having the specific relation among the wavelength, pitch and lattice depth of a light source, and arranging them so as to form approximately the Bragg angle of the lattice with respect to the incident light to the lattice. CONSTITUTION:A surface relief lattice can control an analystic characteristic by a lattice pitch LAMBDA, a lattice depth (d), an incident angle theta, a lattice form, etc. That is, the optical head has at least a light source 8, an image forming optical system to condense light emitted from the light source 8 on an optical disk 13, a photo detector 14 to receive the reflected light from the optical disk 13, a lambda/4 plate 11 and a lattice optical element 10. Here, the lattice optical element 10 is made into the metallic surface relief lattice 10 having a pitch approximately the same as the wavelength with respect to the wavelength lambdaof the light source, and the lattice depth (d) in the relation of 0.75lambda<d<lambda, and it is arranged to form approximately the Bragg angle of the lattice with respect to the incident light to the lattice. Thus, the manufacture of the polarized beam splitter is facilitated, and an inexpensive analytic type element can be substituted for it. |
