O1.2 - An auto-focusing approach for a dynamic quadrature interferometer

Andreas Gollwitzer, Susanne Haugg & Gerhard Fischerauer
The measurement of surface vibrations with small amplitudes is often accomplished using interferometric techniques. For a good local resolution of the vibration amplitudes, the laser beam has to be focused on the surface through a high magnification lens. Owing to the small depth of focus of this lens, its distance to the surface has to be controlled accurately and precisely. In order to avoid the nonlinear components present in heterodyne interferometers (such as acousto-optic modulators)...