  Q & A (quantum electrodynamics test and search for axion) experiment was
first proposed in 1994 and a 3.5 m high-finesse Fabry-Perot prototype detector
extendable to 7 m has been built and tested. We now enter into the 2nd phase of
improving the ellipticity detection sensitivity. We present our scheme, compare
with other ongoing experiments, analyze the displacement spectra of our
suspension system, and use them for designing automatic alignment control to
improve the ellipticicy detection sensitivity. To improve ellipsometry
resolution, we use new polarizers of extinction ratio smaller than 10^{-8}.
