Optical pickup device.

摘要

An optical pickup device capable of maintaining a sufficient amount of laser beam light when recording information on an optical disc and stabilizing the light emission of the semiconductor laser when reproducing information. Each optical component constituting an optical system for an optical pickup device used for both information recording and reproducing is formed with an antireflection film whose spectral reflectance changes in accordance with the wavelength of an incident light. And, in a preferable embodiment, the antireflection film, which has a high spectral reflectance at a shorter wavelength lambda (L) in the whole range of light emission wavelengths covered by the semiconductor laser light source and a low spectral reflectance at a longer wavelength lambda (H), is formed on the incident surface or outgoing surface of at least one optical transparent element (for example, 5). As a result, in recording information on an optical disc wherein a laser beam is emitted at a high output power and at a wavelength lambda shifted to a longer peak wavelength lambda (H), the transmission coefficient of a laser beam becomes high. Furthermore, in reproducing information wherein a laser beam is emitted at a low output power and at a wavelength lambda shifted to a shorter peak wavelength lambda (L), the transmission coefficient of a laser beam becomes low, reducing the amount of light returned to the emission surface of the semiconductor laser.