Position control system for suspended masses in laser interferometer gravitational wave detectors

Abstract
We review and present an analysis of the major issues in the design of test mass control systems for laser interferometergravitational wave detectors. Based on this analysis, we present a design for a computer controlled modular analog servocontrol system which is well suited to the control of a large number of degrees of freedom in long baseline instruments. The system has been tested on an interferometer using multistage cantilever spring isolators. The system enables simple monitoring, testing, and display of many channels simultaneously, while retaining the advantages of analog proportional‐integral‐derivative control electronics.