| 摘要 |
PURPOSE: To obtain the optical head device capable of generating a light spot smaller than a diffraction limit value determined by the wavelength of a light source and the numerical aperture of an objective lens and also performing good recording and reproducing without generating noise but high density. CONSTITUTION: Intensity of light in the vicinity of the center in a cross section of luminous flux of laser light is decreased by an optical modulator 3 in intercepting light with a light intercepting plate in a linear shape inclined at a certain angle to y-axis. Consequently, a light spot on an information surface of an optical disk 6 is shrunk in both x- and y-directions to be smaller than a light spot formed without using the optical modulator 3. An inclined angle of the optical modulator 3 is set to an optimum value based on line density and a track pitch of the optical disk 6 to be used, and adjustment is made not to allow a sidelobe to irradiate pits in front and rear and adjacent tracks, which are being irradiated with a main beam. Only the main beam is transmitted by a light transmission limiting means 10 disposed in a reconverged position. |
