A DISPLACEMENT AND ANGLE INTERFEROMETER WITH SUBATOMIC RESOLUTION

The position and angle measurements discussed in the paper are carried out by application of a displacement-angle interferometer which employs a single laser and is capable of resolutions better than 1 pm and 1 nrad. Angle and displacement values are simultaneously obtained by measuring the phase shifts between four points of the interference pattern with the use of a position-sensitive detector. Though the instrument resembles an optical lever, it is largely insensitive to beam movements, since angle values are obtained by phase rather than position measurements. The interferometer design and performance are discussed, emphasis being given to applications in x-ray/optical interferometry.