dear professor:
    I am a postgraduate student from Tsinghua Univ of China. An article said
that there is a double metal layer which forms a beam. The beam becomes curved
from a bending moment caused by the variation in stress between the two metal
films. Because one metal has a compressive residual stress while the other metal
has a tensile residual stess. We want to use the beam in otptical switch.
  But the article don't tell us what the metal is. Probably some metal can fit
this,such as Au,Al,Cr,Ni,Ti. But we are not sure. Would you please give some
information about the material? Thank you.
                                           yours truly
                                            Suyan Liu
                                            2000.12.4



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