Abstract: A device for measuring vibrations of a rotating blade of a gas turbine includes an optical probe that is mounted within a casing of the rotating blade. The probe includes a light projecting and a light receiving optical fiber along with associated focusing lenses and a protective glass. In addition, liquid coolant channels are provided within the probe housing and air coolant channels are provided within the blade casing in order to protect the probe from the hostile environment of the turbine.

Abstract: A relative displacement control apparatus provides both coarse and extremely fine precise control over displacements between a sample and a detecting probe as required, e.g. in operations of optical instruments, analyzing instruments and scanning tunneling microscopes. This precise fine displacement is produced through a double-lever-action which is created substantially by means of an arm assembly preferably with a piezoelectric drive for precise displacement control, a support pivotally holding the arm assembly, a rigid arm fixed solidly atop the support and a pointed stop or "foot" fixed in the proximity of the free end of the rigid arm.