Abstract: An apparatus for measuring small angular displacement of any object having an attached light reflective surface. A reflecting mirror is attached to the test object for receiving a light beam from a light source and for reflecting the beam toward an angular excursion amplifier. A beam position detector is included in the angular excursion amplifier together with adjustable means for directing the beam toward the beam position sensor. A second beam is directed toward the angular excursion amplifier for impingement upon a reflector mounted upon the adjustable means in the angular excursion amplifier. The reflected second beam is directed toward a scale having a linear gradient calibrated in terms of angular excursion of the test object. In this fashion minute excursion angles of the test object are presented at the scale as amplified linear sweeps of the reflected second beam.