Patent ID: 7697396

Claim:
An optical integrated unit, comprising: a light source for emitting a light beam; light guiding means, so provided as to cross with an optical axis of the light beam, the light guiding means having a function surface that allows passage of the light beam and that reflects returning light, which is the light beam reflected by an optical information recording medium, and guiding the returning light in a direction different from a direction toward the light source; a light receiving element for receiving the returning light guided by the light guiding means; and diffraction means, which diffracts the light beam and the returning light and is provided in a position where the diffraction means crosses with an optical axis of the light beam and where the light beam having passed through the function surface enters, wherein: the diffraction means is a polarized light diffraction element including a first hologram region and a second hologram region, each of which diffracts polarized light having a predetermined polarization plane, and each of which never diffracts polarized light having a polarization plane perpendicular to said predetermined polarization plane but allows passage of the polarized light, and the first hologram region and the second hologram region are so provided as to cross with the optical axis of the light beam, and are provided such that the polarization plane of the polarized light to be diffracted by the first hologram region is perpendicular to the polarization plane of the polarized light to be diffracted by the second hologram region; the first hologram region divides the returning light into non-diffraction light and diffraction light; the light receiving element has (i) a light receiving section for receiving the diffraction light, and (ii) a light receiving section for receiving the non-diffraction light; and the non-diffraction light is used for detection of high-speed signals.