LDH (laser/detector/hologram) unit for thin optical pick-up head of CD player

Abstract

The LDH unit with the size of 4.8/spl times/8.2/spl times/4.3 mm for a thin optical pickup head of a CD player has been successfully developed. The technology to make the LDH unit thin and small is based upon (1) the most efficient optical combination of the low operation current laser diode with the 45/spl deg/ built-in micro-mirror which is formed on the Si photodetector substrate, (2) the thin plastic-molded flat package with good thermal dissipation, and (3) the plastic-molded holographic optical element (HOE) as a cap. The pick-up head using the LDH unit has shown good optical performance sufficient for the application to CD players.<>