This paper presents a novel, universally applicable framework for modelling measured velocity in laser vibrometry systems. The framework is introduced generically before demonstration of its application to three scanning vibrometer systems, each configured to measure vibration of a tracked point on a rotating target. The novelty in this vectorial framework lies in the combination of its elements, which include vector descriptions of target velocity, optical device velocity at deflection points, laser beam orientations, incorporating reflection and refraction, and surface normals. Initial alignment and a full set of inevitable misalignments are incorporated by the modification of position vectors and the use of rotation matrices. Inclusion of components of measured velocity associated with moving optical devices is an important feature of the framework. The models derived and their validation against published data demonstrate how this versatile framework can be applied to any optical configuration measuring target motions with any level of complexity. The individual models are explored extensively and quantitatively through simulation. Small but inevitable misalignments are shown to generate measurable low order velocity components and their effects on the sensitivities to in-plane and out-of-plane components of target vibration are quantified
