Interferometric vibration sensor

A system for measuring unidirectional vibration displacements on a device comprising:

• a sensor affixed to the device and including a structural beam which is secured at its ends with respect to the device, and which is selected in dimension to enable it to vibrate within a selected frequency range exertable on the device for constraining movement of said seismic reference substantially in a single direction, and a reflective element which is secured to said structural beam at its centroid;
• and
• an interferometer for detecting the unidirectional movement,
• said sensor comprising a block having
• first through fifth exterior surfaces, said first, second and third surfaces defining planes which lie perpendicular to one another and said fourth surface defining a plane which is parallel to said first surface,
• said reflective element and said structural beam being secured to said sensor on said first surface,
• first means defining a through bore extending between said first and fourth surfaces and aligned with said reflective element,
• second means defining a bore intersecting said first bore means and extending parallel to said second surface and perpendicularly from said first bore means through said surface, said second bore means lying equidistantly from said second and fourth surfaces, and
• a reflective surface positioned at the intersection between said first and second bore means for enabling electromagnetic energy to be reflected therebetween.