| 摘要 |
PROBLEM TO BE SOLVED: To make it difficult in a disposing deviation of a laser beam to have a short wavelength from a prescribed position and to make it less effected by the aberration of an optical element. SOLUTION: An emitted red light from a semiconductor laser device 1 is transmitted along an optical axis 9 of the red light, and an emitted infrared ray is passed along an optical axis 10 of the ray which is substantially parallel to the axis 9 passing through a diffraction grating 2, and then converted into parallel luminous flux by a collimator lens 3. Furthermore, these light and rays pass through a beam splitter 4 then are made incident to an objective lens 5, and are converged onto an information recording medium 6 by the lens 5. The axis 9, that is, the optical axis of the light having the shortest wavelength coincides with those of the lens 3 and the lens 5. |
