Flying type optical head integrally formed with light source and photodetector and optical disk apparatus with the same

摘要

An optical head including a semiconductor laser source, a condenser lens, a photodiode for detecting a laser light emitter from said semiconductor laser source, and an optical coupler means for collecting the laser light to the photodiode. A chromatic aberration W of condenser lens is satisfied by an expression W(h,NA)={(NA)³&Dgr;&lgr;/4&lgr;}h, where h is a height of incident light from an optical axis on a hologram, NA is a numerical aperture, &Dgr;&lgr; is a wavelength fluctuation, and a &lgr; is a wavelength at recording. The height h is determined so that the chromatic aberration W becomes equal to or less than &lgr;/4.