Paul Scherrer Institut

Mirko Holler

Jörg Raabe

A laser interferometer and a method for operating a laser interferometer perform a differential position measurement by laser interferometry of two elements while offering a rotational degree of freedom to one of the elements using a reflecting sphere as a mirror for the laser beam. The laser interferometer and method do not require the object to be aligned with the rotation axis, but instead can track the object in off-centered geometries. This is achieved by employing the pointing of the reflected beam from the sphere as a feedback signal to realign the interferometer which then has a constant beam pointing to the center of the sphere in all cases. The laser interferometer and method keep the direction of the measurement constant. The laser interferometer and method are suitable for homodyne and heterodyne types of laser interferometer technology.

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Lauchringen, Germany

Mirko Holler