An object is placed at a particular distance away from the nonreflecting side of a mirror, such that the gravitational force of the object affects the mirror. A laser is then pointed at the opposite, reflecting side of the mirror, thereby itself reflecting off the mirror and going back in to the cavity of the laser, creating a mode-hopping effect. The mirror will be affected by three forces, the force of a spring (F.sub.S), the force of a modulating signal (F.sub.MS), created by an electro mechanical device attached to the mirror, and the gravitational force of objects as they approach and recede away from the mirror.