Fiber-diffraction interferometer for vibration desensitization.

We describe a new interferometer designed to obtain high immunity to vibration by generating the reference wave by means of fiber diffraction so as to share a common path with the measurement wave. A spatial phase shifter is added to secure vibration desensitization by capturing four phase-shifted interferograms simultaneously without time delay. Experimental results prove that the proposed interferometer is capable of providing stable measurements with a level of fringe stabilization of less than 1 nm in a typical workshop environment equipped with no excessive ground isolation for antivibration.