Note: Periodic error measurement in heterodyne interferometers using a subpicometer accuracy Fabry-Perot...

Area of Science:

• Metrology
• Optical Interferometry
• Precision Measurement

Background:

• Periodic error significantly limits the accuracy of heterodyne interferometry.
• Accurate measurement of periodic error is crucial for advancing precision engineering and scientific instrumentation.

Purpose of the Study:

• To develop a traceable system for measuring periodic error in interferometry.
• To quantify the periodic error present in commercial heterodyne interferometers.

Main Methods:

• Development of a nonlinearity-free Fabry-Perot (F-P) interferometer system.
• Utilizing an optical frequency comb for precise calibration and referencing.
• Experimental comparison between the developed F-P interferometer and a commercial heterodyne interferometer.

Main Results:

• The developed F-P interferometer achieved a displacement accuracy of 0.49 pm with an 80 ms averaging time.
• The study identified that the first harmonic periodic error is dominant in commercial heterodyne interferometers.
• The amplitude of this dominant error was measured to be 4.64 nm.

Conclusions:

• The nonlinearity-free F-P interferometer provides a traceable and accurate method for periodic error measurement.
• The findings highlight significant periodic error limitations in current commercial heterodyne interferometers.
• This work paves the way for improved accuracy in precision displacement measurements.