Machining, Measurement, and Control Laboratory

'Open-loop' Tracking Interferometer for Three-dimensional Volumetric Error Measurement for Machine Tools
Soichi Ibaraki, Goh Sato

The tracking interferometer is a laser interferometer with a steering mechanism to change the laser beam direction to follow a retroreflector ('target') attached to the machine spindle. Based on the multilateration principle, it measures the target's three-dimensional position at an arbitrary location in the workspace. This paper proposes the 'open-loop' tracking interferometer, where the laser beam is regulated toward the command target position. This eliminates the automated tracking mechanism and thus may significantly reduce the manufacturing cost of conventional tracking interferometers. The paper investigates its measurement uncertainty both analytically and experimentally.
Key words: Tracking interferometer, laser tracker, volumetric accuracy, machine tools, uncertainty.