An optical translation technique for moving the interrogation spot at which a triangulation system measures the displacement of a target is disclosed. In normal operation of the laser triangulation sensor, an incident laser beam is projected from a sensor head onto a surface of a web that is facing the sensor head. Radiation is reflected from the surface and detected by the sensor. The distance from the sensor head to the web surface is calculated by triangulation. With optical translation, both the incident ray path and the captured ray path are translated with a plurality of high refractive index geometries such that the nominal functioning of the triangulation sensor remains undisturbed. The optimal position on the sheet wherein the interrogation spot will be located can be ascertained.