A Method to Calibrate Angular Positioning Errors Using a Laser Tracker and a Plane Mirror.

Area of Science:

• Metrology
• Optical Engineering
• Mechanical Engineering

Background:

• Accurate angular positioning is critical for precision machinery.
• Existing calibration methods for rotation stages can be limited in accuracy and scope.
• Laser trackers offer high precision but require robust calibration techniques.

Purpose of the Study:

• To develop and validate a novel mirror-based method for calibrating angular positioning errors of rotation stages.
• To compare the performance of the proposed method against a direct measurement approach.
• To quantify the uncertainty and accuracy of the new calibration technique.

Main Methods:

• Utilizing a laser tracker (LT) and a plane mirror mounted on the rotation stage.
• Determining the mirror's normal vector via two LT measurements to a stationary spherically mounted retroreflector (SMR).
• Employing stationary registration nests to integrate data from multiple LT stations for full 360° coverage.

Main Results:

• The mirror-based method achieved angular positioning errors of ±0.5 arcseconds.
• This is significantly smaller than the ±1.5 arcseconds error of the direct approach.
• Simulations estimate the uncertainty of the mirror-based method at 0.4 arcseconds (k=2).

Conclusions:

• The developed mirror-based laser tracker method offers superior accuracy for calibrating rotation stage angular errors.
• The technique is more precise than direct measurement methods, with potential for further uncertainty reduction.
• Optimal placement of the laser tracker and spherically mounted retroreflector enhances measurement certainty.