Uncertainties in Small-Angle Measurement Systems Used to Calibrate Angle Artifacts

Area of Science:

• Metrology
• Optical Engineering
• Surface Metrology

Background:

• Small-angle measurement systems are crucial for calibrating artifacts like optical polygons.
• Quantifying errors from non-flat artifact surfaces is challenging, impacting orientation interpretation.
• Existing methods face difficulties in accurately assessing uncertainty in surface orientation measurements.

Purpose of the Study:

• To investigate and compare error sources in small-angle measurement systems.
• To evaluate the performance of Fizeau phase-shifting interferometers against autocollimators for artifact calibration.
• To explore the potential of interferometry as an alternative for precise small-angle measurements.

Main Methods:

• Comparison of angle measurements using an autocollimator and a Fizeau phase-shifting interferometer.
• Calibration of optical polygons and analysis of measurement uncertainties.
• Investigating the impact of imperfect, non-flat artifact faces on measurement accuracy.

Main Results:

• Autocollimator and interferometer measurements showed no significant differences in results.
• The Fizeau interferometer provides a clear and robust definition of surface orientation.
• Quantifying interferometer measurement errors appears more straightforward than autocollimator uncertainties.

Conclusions:

• Fizeau phase-shifting interferometers offer a promising alternative to autocollimators for small-angle measurements.
• Interferometry simplifies the quantification of measurement uncertainty, especially with imperfect surfaces.
• Further research may validate interferometers as a superior tool for precise artifact calibration.