Compact design for a unitary photo detector and single-path combo optical pickup head for Blu-ray disc, digital versatile disc and compact disc systems

We present a compact design for a unitary photo detector and single-path combination optical pickup head (OPH) which can be used for Blu-ray Disc, digital versatile disc and compact disc systems. The number of components in the OPH design can be reduced by focusing three discrete wavelength laser beams on the photo detector. The three laser diode chips and a photo detector can be encapsulated within an integrated optical unit (IOU), which is then combined with a compensator and rhomboid beam-splitter prism. The blazed holographic optical elements (HOEs) are designed for concentrating the diffracted light power to the 0th-order and the 1st-order to improve the round-trip efficiency. The simulation results, including the S-curve and optical efficiency, are compared for this combo-OPH with three IOUs. The optical efficiency of the proposed OPH for BD/DVD/CD systems as detected by the photo detector are 5.545%, 3.889%, and 3.517%, respectively. Our design results show that the combo-OPH with one IOU is better than the combo-OPH with three IOUs.