OPTICAL PICKUP DEVICE

PROBLEM TO BE SOLVED: To provide an optical pickup device that smoothly restricts the influence of stray light and reduces its costs low.SOLUTION: The directions of travel of laser beams passing though luminous flux areas f1 to f4 change when vectors V21 to V24 are applied thereto. The directions of the vectors V21 and V22 are the same, and the directions of the vectors V23 and V24 are the same. The magnitude of the vector V21 is greater than that of the vector V22, and the magnitude of the vector V24 is greater than that of the vector V23. In this manner, detection signals based on laser beams (signal light) passing through the luminous flux areas f1 to f4 can be obtained by sensors arranged in rectangular signal light areas 1 and 2. Additionally, since a spectroscopic element composed of an inexpensive step type diffraction pattern can be used for applying the vectors V21 to V24, the costs of the optical pickup device can be reduced low.