Abstract
An interferometric accelerometer developed for use in characterizing isolation systems for gravitational wave detectors is described. A Nd:YAG laser is frequency locked to a Fabry–Pérot cavity in which one mirror is flexibly mounted. At 100 Hz the displacement sensitivity is 1.0×10−14 m/√Hz, 100 times more sensitive than the piezoelectric accelerometers normally used for such measurements. The sensitivity of the accelerometer is limited by the frequency noise of the laser.