Single Channel Self-Mixing Interferometer Measures Simultaneously Displacement and Tilt and Yaw Angles of a Reflective Target

We show that a self-mixing interferometer can supply not only to the usual optical-phase signal cos 2ks(t) of the external reflector displacement s(t), but also the attitude signal P(a) because of the dependence of power from the angle a between wavevector k and normal n to the target reflective surface. By proper interrogation of P(a) along two orthogonal components of tilt and yaw, the two angles can be measured simultaneously, together with the displacement, in a single self-mixing interferometer channel implemented by a single-laser diode and monitor photodiode combination.