| 摘要 |
PURPOSE:To emit diffraction light beams in a direction parallel to the optical axis of an objective lens by permitting an output signal from a luminous flux direction detection means to control an angle between the optical axis 8 of the objective lens and the direction of the luminous flux toward the objective lens. CONSTITUTION:Control means 36 and 24 which control the angle between the optical axis of the objective lens 7 and the direction of the luminous flux from a diffractiong rating 10 toward the objective lens 7 by the output signal from the luminous flux direction detection means 23 detecting a change in the oscillation wavelength of the light source of a semiconductor laser 11 are provided. Even if a high frequency is superimposed on the driving signal of the semiconductor laser 11 in consideration with a return light beam for the semiconductor laser 11, or the light beam different in a wavelength is included in the luminous flux to be emitted since a temperature rises in the semiconductor laser 11 itself, the optical beam spot on the recording medium can be shaped, and information can accurately be recorded and reproduced by controlling the outgoing angle of the diffraction luminous flux in the diffraction grating 10. Thus, matching to the optical axis of the objective lens is attained and high performance can be secured. |
