| 摘要 |
PURPOSE:To stabilize the operation of a semiconductor laser by tilting a 1/4 wavelength plate within a plane orthogonal to an optical axis. CONSTITUTION:Most of luminous flux passes through a polarized beam splitter 3 as it is and is made incident in the 1/4 wavelength plate 4. Since the 1/4 wavelength plate 4 is tilted within a plane orthogonal to the optical axis, the luminous flux linearly polarized and the crystal axis X are not formed to be 45 deg., resulting that the luminous flux is passed without being subject to circularly polarized effect. The incomplate circularly polarized luminous flux passing through the 1/4 wavelength plate 4 is reflected in an information recording medium 6 and made incident again in the 1/4 wavelength plate 4, the incomplete circularly polarized luminous flux goes to partial linearly polarized light and passes through the plate and made incident in the polarized wave beam splitter 3. The luminous flux passing through the splitter 3 passes again through a collimator lens 2, is fed back to a semiconductor laser 1 and the rate of the returned luminous quantity to the irradiated luminous quantity is increased. Thus, stable optical information recording/reproduction is attained. |
