For the purpose of backward compatibility to the CD and DVD specifications, the optical pickup head (OPH) design with multiple laser wavelengths and numerical apertures (NAs) is necessary for the Blu-ray Disc (BD) system. By utilizing the features of an integrated optical unit (IOU) and a holographic optical element (HOE), this study presents a novel three-wavelength BD OPH configuration with compactness in a single optical path. There are two OPH designs with the astigmatic and knife-edge focusing detection methods applied to the IOU configurations in this paper, respectively. The simulation results are satisfactory and show the feasibility of the designs.
