Homodyne laser vibrometer capable of detecting nanometer displacements accurately by using optical shutters

This paper describes a homodyne laser vibrometer with optical shutters. The parameters that define the nonlinearity of the quadrature signals in a vibrometer can be pre-extracted before the measurement, and can then be used to compensate for nonlinear errors, such as unequal AC amplitudes and DC offsets. The experimental results indicated that the homodyne laser vibrometer developed has the ability to accurately detect the vibration state of the object to be measured, even when the amplitude is ≤λ/4. The displacement residual error can be reduced to a value under 0.9 nm.