A measurement of the in-loop error signal gives a lower limit on the frequency noise in the laser. An analyzer cavity is then locked to the laser by actuating its temperature. The error signal from this cavity will contain both frequency noise and cavity noise and so will give an upper bound for the laser frequency noise. Thermal noise is the major limiting factor in a gravitational wave detector and the TNI intends to study and minimize it. Laser frequency noise competes with thermal noise in the TNI and must be understood before an effective measurement can be made.
Electrostatic actuators exert a force on a dielectric mirror without touching it.
This allows one to move the LIGO test mass mirrors or possibly even levitate them without spoiling the mechanical quality factor. We investigated the theoretical properties of various electrostatic actuator configurations. In particular, the thermal noise generated by intrinsic electrical loss in the dielectric mirrors was calculated. Phil Willems Suspensions for high-quality pendula using uniform steel fibers are well understood. We want to determine the magnitude of this effect, and to suggest optimal taper designs.