Patent ID: 8144564

Claim:
An optical head unit comprising: a first light source with a first wavelength; a second light source with a second wavelength, the second wavelength being longer than the first wavelength; a first collimator lens that changes the degrees of divergence of the light that has been emitted with the first wavelength from the first light source; a first vertical reflecting mirror that changes the traveling directions of the light with the first wavelength that has had its degrees of divergence changed by the first collimator lens; a first objective lens for converging the light with the first wavelength that has been vertically reflected by the first vertical reflecting mirror onto a storage layer of a first optical disk; a mover that holds the first objective lens; a first photodetector that receives the light with the first wavelength that has been converged by the first objective lens onto the storage layer of the optical disk and then reflected from the optical disk and that converts the light into an electrical signal; a beam splitter that diverts the light with the first wavelength that has been emitted from the first light source away from the first collimator lens; and a base that holds an optical member, wherein the base has an arced recessed portion, and wherein the first photodetector is arranged in a substantially straight continuous portion of the base that connects to an end of the arced recessed portion on the periphery of the base.