Blu-ray Disc Pickup Head for Dual Layer

For dual-layer Blu-ray disc (BD) recording systems, the compensation of thickness differences is required. In addition the influence from the other layer should be considered. As a spherical compensation method, we have adopted a liquid crystal panel to fabricate a compact pickup head. Furthermore we have inserted a polarization diffractive optical element to reduce the influence from the other layer. In this paper, we report the readout test results of a dual-layer disc using a compact optical head.