Abstract
LIGO will detect gravitational waves using laser interferometers that will be quantum noise limited over most of the apparatus's operating frequency range. Before one can build an interferometric gravitational wave detector that works at the limits set by quantum mechanics, it is necessary to first build a detector that one can control and read out optically. In the LIGO interferometer, several photodiodes are used to sense various degrees of freedom and to provide feedback signals to position the mirrors so that the optical cavities will be in optical resonance. In addition, the main interferometric gravitational wave signal is read out with a photodiode. In this sort of precision physics experiment it is necessary to treat the photodiode and its readout electronics as systems whose performance, including frequency response, can change over time and with changing operating conditions. The goal of this project is to build an automatic frequency response measurement system for the gravitational wave detector photodiodes. This system will use a modulated diode laser coupled through a fiber optic distribution system to illuminate the photodiodes and then automatically and quickly measure the frequency response of each photoreceiver using a network analyzer and an RF switch to select the photodiodes one after another. The experiment will be carried out at Caltech on the LIGO 40m prototype interferometer.
Documents
Work plan: https://dcc.ligo.org/LIGO-T1300561
RF photoreceiver schematics: https://dcc.ligo.org/LIGO-D1300586
Laser Module Documentation: https://dcc.ligo.org/LIGO-D1300587
What's going on right now
Working on drawing diagrams with Inkscape... crude laser module diagram completed.
Beginning familiarization with network analyzer and GPIB...