Abstract

We have shown long term stability of two picometers in measurements on an unequal-arm Michelson distance gauge; we will soon test a design for point-to-point distance measurements. Frequency-modulated laser light enters the interferometer through a single-mode optical fiber; distance changes cause amplitude modulation of the emerging light, which is synchronously detected to provide a correction signal for a servo. We have also reduced the distance errors arising from ac interferometric production of amplitude modulation in the fiber; the angle-cleaved ends now reflect less than one-millionth of the incident laser intensity back into the fiber.

© 1992 Optical Society of America