Abstract: A simple, novel and reliable two-dimensional, cantilever based fiber optic acceleration and vibration sensor, able to measure constant and/or variable acceleration, velocity, displacement, and frequency spectrum simultaneously in two perpendicular directions is presented. The sensor has a long live-span, high sensitivity, wide dynamic range and linear response in both directions. According to one aspect of the present invention, the two-dimensional fiber optic accelerometer includes an elongated light conducting elastic member with a round cross-section which first end is coupled to a light emitting source. The elastic member can be an optical fiber, and is mounted on a support structure in such a way that its second end forms a cantilever. A lens focuses the light irradiated from the elastic member onto a dual axis position photosensor. Thus, the lens, the elastic member and the photosensor form an optical lever.