PURPOSE: To form the converged spot of a circular shape in an optical pickup device.
CONSTITUTION: On the middle of a semiconductor laser 11 emitting a divergence light beam with a different extending angle in the direction of X, Y perpendicular to an optical axis and a converging optical system consisting of a collimate lens 12 and an objective lens 13, glass plates 14, 15 arranged with an inclination to the optical axis are provided. An outgoing light beam diverged from the semiconductor laser 11 is converged on an optical disk 20 by the converging optical system. The reflected light beam from the optical disk 20 is reflected respectively by the glass plates 14, 15 and received by photodetectors 21, 22 while being converged by the converging optical system. Based on the output signal of the photodetectors 21, 22, a data reading signal, a tracking error signal and a focusing error signal are formed. On the glass plate 14, the distribution of transmittance controlling the intensity of the transmitting beam so that the distribution of the intensity in the cross-section of the beam converged by the above-mentioned converging optical system is same roughly in the direction of X, Y intersecting orthogonally with the optical axis is formed.
HOSOKAWA HAYAMI
HORIE NORISADA
KIYOMOTO HIRONOBU
