| 摘要 |
PURPOSE: To obtain an optical head device which can be miniaturized and enhanced in performance by using an optical system block which forms a diffraction grating region and a simple transmission region and realizes a function required for a luminous flux by means of a single component. CONSTITUTION: A luminous flux 2 which is radiated from a light source 1 is diffracted and separated by a diffraction grating 31 on a face 35 for an optical element block 30, it is incident on a diffraction grating 32 on a face 36, it is then incident on a condensing lens 7, and it is condensed on an information recording face for an optical information recording medium 12. Then, a luminous flux reflected by the recording medium 12 is transmitted through the condensing lens 7, it is separated from the luminous flux 2 as a reflected luminous flux 6, it is transmitted through an antireflection coating region 33, and it is then incident on a photodetector 19. In this manner, by using the optical element block 30 which realizes the function of a diffraction grating, a half mirror and a lens system as an optical system for a focusing sensor by means of one component and which eliminates a need of adjusting components mutually, the costs of an optical head device are lowered, and its assembly property can be enhanced. |
