A Micro-Focusing Stage Applied to Optical Pick-Up Head

Presently, various micromachined actuators have been employed to tune the tracking and focusing of the light beam of optical pick-up head [1–2]. This work demonstrates a novel micro-focusing stage for optical pick-up head application. As in Fig. 1a, the presented micro-focusing stage for optical pick-up head is consisted of four parts: out-of-plane actuator, connecting joint, through hole, and focusing lens plate. The stress-induced beams acted as the self-assembly mechanism to lift up focusing lens plate. In addition, the stress-induced beams also acted as the out-of-plane electrostatic actuator after deposited with an electrode layer. Unlike the design in [3], a through hole underneath the lens plate is allowed in this case for the incident light beam. After properly driving the stress-induced beams, the position of the focusing plate was controlled, as shown in Fig. 1b. The stage had piston motion to adjust the focal point of the lens. Moreover, the stage had tilt motion, so as to ensure that the lens paralleled the disk surface. Thus, the incident laser beam was always orthogonal with the disk surface.