Highly accurate imaging based position measurement using holographic point replication

The experimental approach of a highly accurate imaging based stereo measurement setup with a total measurement volume of 140 mm x 100 mm x 50 mm is presented. The system can detect the position of multiple target points (LEDs) in a calibrated volume of 100 mm x 75 mm x 24 mm with an accuracy of sigma(x) = 0.367 mu m, sigma(y) = 0.373 mu m and sigma(z) = 0.437 mu 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 mu m is sigma(d) = 0.242 mu m and for a three-dimensional trajectory of distance D = 57.2 mm it is sigma(d) = 0.674 mu m.

Automated summary

The experimental approach presents a highly accurate imaging-based stereo measurement setup with the ability to detect multiple target points with great precision. By holographically replicating each point light source and averaging the center positions of all spots on the camera sensor, the system achieves high accuracy.Validation with interferometers as reference sensors shows minimal residual error in two- and three-dimensional trajectory measurements.