Patent ID: 6920098

Claim:
An optical pick-up device comprising: a light source provided with a holographic unit adapted to diffract a light beam; an optical disc adapted to allow data to be written thereof or to be read therefrom; a monitor photodiode served to monitor a laser power of the light source; and a lens for light collection arranged between the light source and the monitor photodiode and adapted to converge a first-order diffracted beam outputted from the holographic unit and to apply the converged first-order diffracted beam to the monitor photodiode, including: a lens face for converging the first-order diffracted light beam; a total reflective face for totally reflecting the converged first-order diffracted beam; and an exit face for transmitting the reflected first-order diffracted beam to the monitor photodiode, wherein the lens face has a spherical shape convex toward the light source.