Transforming a green laser pointer in a self-mixing interferometer capable of submicrometer vibration sensing

We show that, by adding a photodiode and a plain glass beam splitter to a commercial green laser pointer, we can obtain a very sensitive self-mixing interferometer capable of detecting minute vibrations down to submicrometer amplitude, typically ≈13nm resolution, or make displacement measurements with half-wavelength (λ/2=266nm) count increments.