Speaker
Description
The force required on the mirrors for interferometer lock acquisition can be reduced below 0.25 mN if the pendulum modes are actively damped to levels below the Low Noise Peterson model. The required locking force can be applied using the rigid suspension beams as mechanical levers by mounting electrostatic actuators between the beam counterweights and the intermediate mass. This approach eliminates the need for a recoil mass or additional structure near the mirror. For a parallel-plate electrostatic actuator with an area of 25 cm² and a separation of 500 μm, the required locking force can be achieved with voltages below 100 V. These voltages can be generated by external low-noise electronics and delivered inside the cryostat using the cryogenic heat-link wires as conductors. The same actuators can provide yaw control.
Similar electrostatic actuators applied to the vertical springs can be used to modify the effective spring stiffness, enabling additional vertical attenuation as well as pitch control.