Highly accurate imaging based position measurement using holographic point replication

Abstract

Abstract The experimental approach of a highly accurate imaging based stereo measurement setup with a total measurement volume of 140\xa0mm\xa0 × \xa0100\xa0mm\xa0 × \xa050\xa0mm is presented. The system can detect the position of multiple target points (LEDs) in a calibrated volume of 100\xa0mm\xa0 × \xa075\xa0mm\xa0 × \xa024\xa0mm with an accuracy of σ x = 0 . 367 μ m, σ y = 0 . 373 μ m and σ z = 0 . 437 μ m. This high accuracy is reached by holographically replicating each point light source to a predefined pattern (cluster) of spots on the camera sensor and averaging the center positions of all spots. We present a detailed description of the principle, the process and results of calibration including deformation compensation and stability measurements, as well as the results of two- and three-dimensional trajectory measurements. To validate the performance and accuracy of the measurement setup, interferometers are employed as reference sensors. The residual error of a two-dimensional trajectory of distance D = 277 μ m is σ d = 0 . 242 μ m and for a three-dimensional trajectory of distance D = 57 . 2 \xa0mm it is σ d \xa0=\xa00.674\xa0 μ m.