Based on the theory of the multi-beam amplitude comparison DF of the new-style radar detector, the DF blind zone of multi-beam radar detector on inner site is analyzed in this paper.

For fixed damping and fixed excited frequency the motion of the beam under small amplitude of force is periodic, but becomes chaotic through period doubling bifurcation with increase of the force.

In the paper. the interference intensity of signal laser beam and the reference one is carried out in detail on a heterodyne laser probe with amplitude modulated laser source.