| 摘要 |
PURPOSE:To perform a stable error detecting operation without being affected by the fluctuation of the wavelength of a light source by constituting the title device so that it can be arranged at a position where an incident light quantity on the first area of a waveguide type light beam separation means becomes equal to the sum of incident light quantities on second and third areas in case where emitting light is converged correctly on an optical recording medium. CONSTITUTION:Reflected light beams from an optical disk are made incident on a waveguide type error detecting optical device having a grating coupler, a waveguide type branching filter, and an optical detector on a waveguide substrate. The waveguide type branching filter 6 is separated to the first area 19, the second area 20, and the third area 21, and functions to guide the light so that incident light on respective area can be made incident on first, second, and third optical detectors arranged at the end of a waveguide. The first area 19, the second area 20, and the third area 21 of the waveguide type branching filter 6 are set so that the incident light quantity on the first area 19 can be set equal to the sum of the incident light quantities on the second area 20 and the third area 21 when reflecting collimate light 17 is made incident. In such a way, it is possible to obtain an optical head device on which no influence of the fluctuation of the wavelength of the light source is given and by which the stable error detecting operation can be performed. |
