Two-step retrace error calibration removing tilt ambiguity in coherence scanning interferometry.

Area of Science:

• Optical metrology
• Interferometry
• Precision engineering

Background:

• Retrace error in interferometry limits high-precision measurements.
• Existing calibration methods using tilted flats have inherent tilt ambiguity.

Purpose of the Study:

• To propose a novel two-step calibration method to resolve tilt ambiguity in interferometry.
• To improve the accuracy of retrace error calibration.

Main Methods:

• A two-step calibration approach is introduced.
• Additional measurements using spherical mirrors with known curvatures are incorporated.
• The method addresses the ambiguity between introduced tilt angles and retrace error tilt terms.

Main Results:

• The proposed method effectively resolves tilt ambiguity.
• Significant reduction in curvature deviation caused by tilt ambiguity was observed.
• Enhanced accuracy in interferometry measurements is achieved.

Conclusions:

• The novel two-step calibration method successfully overcomes tilt ambiguity in interferometry.
• This advancement is crucial for high-precision metrology applications.
• The technique offers improved accuracy and reliability in optical measurements.