Prototype Michelson interferometer with Fabry-Perot cavities

We describe a rigid, internally modulated Michelson interferometer with Fabry-Perot cavities in the interferometer arms. The high contrast (0.986) and the small cavity losses (2.7%) permit efficient use of the light power available. The measured shot-noise-limited displacement sensitivity for 35mW of light power is 2.5 x 10(-17) m radicalHz, in good agreement with the calculated signal-to-noise ratio.