In one aspect, an apparatus for estimating a characteristic of a sensor is disclosed that in one embodiment may include a chamber housing sensor, wherein the sensor includes a suspended movable force mass having an opening therethrough, a first partially reflective member that moves with the force mass and a second partially reflective member spaced from the first partially reflective member, a source of buoyant fluid configured to supply the buoyant fluid to the chamber at a plurality of pressures, a device for directing light to the first and second partially reflective members at a plurality of angles, a detector for providing signals corresponding to light passing through the second partially reflective member corresponding to each of the plurality of angles and each of the plurality of pressures, and a processor for determining the characteristic of the sensor from the signals provided by the detector.