The invention relates to a system and method for detecting the displacement, such as the deflection, of a plurality of elements (1), such as microcantilevers, forming part of an array (2), by emitting a light beam (4) towards the array (2) and by receiving a reflected light beam on an optical position detector, whereby the position of incidence of the light beam is determined by the displacement of the corresponding element. The system further comprises: scanning means (7) for the displacing the light beam (4) along the array (2) so that the light beam is sequentially reflected, by the individual elements (1) along said array (2); and reflection detecting means (11) for detecting when the light beam is reflected by an element. The system is arranged so that when the reflection detecting means (11) detect that the light beam is reflected by an element, the corresponding position of incidence of the light on the detector is taken as an indication of the displacement of the element.