Making a high-precision positioning apparatus by an optical pickup head module

Abstract

A linear moving stage using a commercially available optical pickup head as the key element of the whole system was constructed. An additional object carrier was rigidly mounted to the lens module so that the carrier moved synchronically and consistently with the lens module. The carrier platform can carry light weight objects, such as bio-cells for manipulation or optical fiber in alignment application. A CD holder with a small part of the optical disk taken from a CD was located in front of the lens module. The focusing error signal from the photo diode was used to indicate the position between the carrier platform and the CD. A digital lead compensator with integrator was implemented to improve the transient response and positioning accuracy. Experimental results showed that the moving stage with the above arrangement can successfully achieve the positioning for micro, submicron and 50 nm position commands within the overall moving range of 10 mum. The feasibility of creating a low cost accurate positioning system using an optical pickup head module was successfully demonstrated in the architecture. The cost of the precision positioning system is far cheaper than other precision positioning systems nowadays. The concept of the proposed positioning apparatus can be further extended into making a two stage of moving in X and Y directions by using focusing and radial error signals at the same time.