An integrated Fizeau-type interferometric displacement sensor for a feedback-controlled actuation system

A hybrid micro-displacement sensor based on a Fizeau-type interferometer has been developed. The proposed sensor structure includes a polyimide waveguide, a distributed feedback laser diode, a two-segment edge-illuminated refracting-facet photodiode, a polarization beam splitter plate, a quarter-wave plate, and a beam splitter plate all on a silicon substrate (2 mm /spl times/ 3 mm). The sensor was fabricated by means of a passive alignment technique using alignment marks with an alignment accuracy of /spl plusmn/1 um. By using this sensor and an electronic feedback system, the position of a mirror actuated by a piezoelectric transducer can be servo-controlled. Nanometer-scale positioning of the mirror was accomplished with good stability against creep phenomena of the piezoelectric transducer.