| 摘要 |
PURPOSE: A beam-shaping device, an optical disc device, and a fabrication method of the beam-shaping device are provided to suppress aberration produced by wavelength variation of light sources and improve diffraction efficiency. CONSTITUTION: A beam-shaping device(10) comprises a first surface(10a) having a first diffraction grating through which a beam of light, emitted from a light emitting point on an optical axis, passes, and a second surface(10b) having a second diffraction grating through which the beam of light, having passed through the first surface, passes. The first diffraction grating and the second diffraction grating are designed, so as to maintain, when the wavelength of the emitted beam of light varies, a prescribed relationship between the displacement of a first virtual light emitting point, in a first meridian plane containing the optical axis, associated with the beam of light having passed through the first surface and the second surface, and the displacement of a second virtual light emitting point, in a second meridian plane perpendicular to the first meridian plane, containing the optical axis, associated with the beam of light having passed through the first surface and the second surface.
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