Scanning LDV using wedge prisms

Recent work on laser vibrometry proposed a mathematical model for the velocity sensed by a laser beam incident in an arbitrary direction on a rotating target undergoing arbitrary vibration. A single arbitrary point along the line of incidence of the laser beam must be known, together with an arbitrary known point along the line of the beam and the main purpose of this paper is to introduce a general procedure to determine both. This new procedure is applied to a novel, scanning LDV arrangement in which rotating wedge prisms are used in order to track a rotating component. Special attention is given to the time-dependent laser beam orientation using a vector description of refraction to enable concise expression. Experimental data are presented for the first time suggesting advantages over the convention dual-mirror system currently used for tracking LDV.