Dear Ms. Zhang:

>We are trying to design a micro-mirror with a deflection angle of 40 to 45
>degree. However, if we use torsion hinge, the stress of the hinge at 45
>degree exceeds the yield strength of most materials. I wonder whether you
>have any suggestion about what materials and what hinge types are best
>suitable for this kind of application.

If I properly understand your problem, it is that you want a large range of
deflections for your mirror mount.  Many materials will not withstand such
large displacements and strains without going into plastic deformation,
which is not acceptible.  I wonder if you might consider "folded beam"
configurations.  These are used in airbag accelerometers; they provide
large deflections with virtually no yield stress problems.  It just might
be possible to adapt the folded beam configuration to a torsional mirror
mount.  This is just a thought that might get you thinking "out of the
box".  Good luck.

Tom Jones



***********************************************
*  Thomas B. Jones                            *
*  Professor of Electrical Engineering        *
*  University of Rochester                    *
*  Rochester, NY  14627   USA                 *
*  phone: 716-275-5233                        *
*  email: [email protected]              *
*  www: http://www.ece.rochester.edu/~jones/   *
***********************************************