OPTICAL HEAD

摘要

An optical head having a simple structure, which achieves high optical efficiency while reducing spot size by apodization. A diffraction element (2) for diverging light to a signal-detecting photodetector is arranged between a light-emitting and detecting element (1) and an object lens (4). The diffraction element (2) comprises a first area where a diffraction grating is formed and a second area where no diffraction grating is formed. The first area is located in the center of the luminous flux toward the object lens (4) from a light source so that apodization will take place with decreased transmissivity to reduce optical losses due to the apodization.