Optical Pathlength Noise in Sensitive Interferometers Due to Residual Gas

Document #:

LIGO-T952011-v1

Document type:

T - Technical notes

Abstract:

An analysis of the noise in the apparent optical pathlength in an interferometer due to
the presence of statistical fluctuations in the passage of gas molecules through a laser
beam is presented. An experimental test using a 40 m long prototype interferometer
confirms the main predictions of the model regarding the dependence on frequency,
pressure, molecular polarizability and molecular speed. The results are used to derive
the vacuum requirements for the planned Laser Interferometer Gravitational-wave
Observatory (LIGO).

Files in Document:

• PDF (SKM_22723042408400.pdf, 499.4 kB)

Topics:

• Vacuum
• Requirements
• Document Migration from the old DCC

Authors:

• Rainer Weiss
• Stan Whitcomb
• Michael Zucker

Notes and Changes:

Unpublished draft combining elements of T840003, T890025 and P940008.

Related Documents:

• LIGO-T840003: Optical Pathlength Fluctuations in an Interferometer Due To Residual Gas
• LIGO-P940008: Measurement of Optical Path Fluctuations due to Residual Gas in the LIGO 40 Meter Interferometer