A non-contact measurement of position, movement, and vibration is possible with PSM modules. The heart of these devices is a silicon chip made by the Swedish company Sitek.

The sensor is delivered as a complete unit with housing. It is "plug-and-play" compatible with any position sensor amplifier that creates an analogue output signal proportional to the x and y position of the incident light. In most cases, the extremely low linearity error (which is typically 0.3%, but can reach a maximum of 1%) across the whole area renders any corrections using complicated tables obsolete.