Polarization grating based circular subaperture stitching interferometer insensitive to vibration and alignment...

Area of Science:

• Optical metrology
• Precision engineering
• Nanotechnology

Background:

• Subaperture stitching interferometry is crucial for high-resolution measurement of large-aperture, high-slope aspheres, extending dynamic range.
• Traditional methods often demand high-precision multi-axis motion control and vibration-free environments, limiting practical applications.
• Existing techniques are susceptible to mechanical adjustments and alignment errors, impacting measurement accuracy.

Purpose of the Study:

• To propose a novel polarization grating-based circular subaperture stitching interferometer.
• To develop a virtual-real combination algorithm for enhanced measurement accuracy and robustness.
• To achieve non-null measurement that is insensitive to vibration and alignment errors.

Main Methods:

• Utilized a polarization grating for subaperture scanning via axial rotation, replacing complex multi-axis systems.
• Employed polarization phase-shifting interferometry for transient, single subaperture measurements.
• Implemented a virtual-real combination algorithm to mitigate retrace and alignment errors.

Main Results:

• The proposed system is more compact and reduces errors from mechanical adjustments compared to traditional methods.
• Demonstrated improved insensitivity to vibration during individual subaperture measurements.
• The virtual-real combination algorithm effectively suppressed retrace errors and reduced alignment error impact.

Conclusions:

• The polarization grating-based circular subaperture stitching interferometer offers significant insensitivity to vibration and large alignment tolerance.
• The system and virtual-real combination algorithm provide a robust and accurate solution for aspheric surface metrology.
• This research offers innovative insights for advanced optical measurement techniques.