This paper reports a preliminary study of recently proposed vibration sensor using an external cavity laser sensor. The behavior of the sensor is compared with conventional laser interferometers used for aerospace applications. It is found that the new method has advantages in the relatively few optical components that are required, namely: a collimated laser diode, and a reflective surface at the point of incidence on the structure. In addition, output of the device is an absolute measure of displacement. As well as outlining the principle of operation of the device, the practical issues of application are discussed. Although the system is still in development it offers the prospect of a low-cost, robust alternative to standard laser vibrometry.