A Six-Degree-of-Freedom (6-DOF) Simultaneous Measurement Method Using Dual-Wavelength Laser Sources for Compensation...

Area of Science:

• Metrology and Precision Engineering
• Optical Measurement Techniques
• Mechanical Systems Analysis

Background:

• Geometric errors in linear guides significantly impact precision equipment accuracy.
• Accurate measurement of six degrees of freedom (6-DOF) motion errors is crucial for high-end machinery.
• Air turbulence degrades measurement accuracy in long-distance straightness assessments.

Purpose of the Study:

• To develop an efficient and accurate 6-DOF simultaneous measurement method for linear guides.
• To mitigate the effects of air turbulence on straightness measurement accuracy.
• To validate the proposed method's performance against traditional techniques.

Main Methods:

• Integration of heterodyne interferometry, collimation/autocollimation, and polarization principles for 6-DOF measurement.
• Implementation of a dual-wavelength laser-based compensation method to suppress turbulence-induced beam deviation.
• Establishment of a turbulence compensation model based on a dual-wavelength proportional cancellation principle.

Main Results:

• The proposed method significantly improves straightness measurement stability by over 56% compared to the simple moving-average (SMA) filter.
• Achieved high repeatabilities for 6-DOF motion errors: 6.4 μm (positioning), 6.4/5.5 μm (straightness), 1.7″/2.1″ (yaw/pitch), and 4.3″ (roll) over a 3200 mm range.
• Effectiveness verified through COMSOL simulations and experimental studies.

Conclusions:

• The developed simultaneous 6-DOF measurement method offers high accuracy and robustness for linear guides.
• The dual-wavelength compensation effectively suppresses air turbulence, enhancing measurement reliability.
• This technique is well-suited for precise motion error assessment of long linear guides in demanding applications.