別体型ホログラム素子を用いた2焦点ピックアップ

抄録

We have developed a dual focus optical pickup with a holographic optical element (HOE). The optical pickup uses a laser diode with a wavelength of 835/650nm and an objective lens with a numerical aparture (NA) of 0.6. HOE causes an useless incident light to a photo detector (PD). Using an eccentricity of HOE, we can avoid an useless signal. And we found that a suitable tilt angle of a pickup and a object lens reduces a coma aberration by the eccentricity of HOE.