We present a point-diffraction interferometer that has been specially devised to perform absolute distance measurements in three dimensions. It is composed of two main parts: One is a target that moves in three dimensions, and the other is a stationary two-dimensional array of photodetectors. The target is made of point-diffraction sources that emit two spherical wave fronts, whose interference is monitored by the photodetectors. Application of a phase-shifting technique allows the phase values of the photodetectors to be precisely measured, which are then fitted to a geometric model of multilateration so as to determine the <i>xyz</i> location of the target by minimization of least-squares errors. Experimental results show that the proposed diffraction interferometer is capable of measuring the <i>xyz</i> coordinates of the target with a volumetric uncertainty of less than 1.0 μm over a working volume of a 100-mm side.
© 2002 Optical Society of America
(050.5080) Diffraction and gratings : Phase shift
(060.2310) Fiber optics and optical communications : Fiber optics
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.3940) Instrumentation, measurement, and metrology : Metrology
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
Hyug-Gyo Rhee and Seung-Woo Kim, "Absolute Distance Measurement by Two-Point-Diffraction Interferometry," Appl. Opt. 41, 5921-5928 (2002)