A Compact Dual-Oblique-Fiber Heterodyne Phase-Shifting Point Diffraction Interferometer.

Area of Science:

• Optical Engineering
• Metrology
• Interferometry

Background:

• Point diffraction interferometers (PDIs) are crucial for high-quality optical testing due to their reference wavefront generation.
• Existing PDI designs can be complex and costly, limiting their widespread application.

Purpose of the Study:

• To propose and demonstrate a compact, low-cost, and highly stable dual-oblique-fiber heterodyne phase-shifting point diffraction interferometer (DOF-HPSPDI).
• To enable precise optical testing and sub-aperture stitching of large-aperture optical components.

Main Methods:

• Development of a novel dual-oblique-fiber point diffraction wavefront generator (DOF-PDWG) for separate reference and measurement beam generation.
• Utilizing heterodyne phase-shifting interferometry (HPSI) for accurate wavefront phase retrieval.
• Analysis of theoretical system errors via simulations and experimental validation.

Main Results:

• Successful demonstration of a compact and stable DOF-HPSPDI system.
• Efficient utilization of fiber-generated diffracted wavefront divergence and common path propagation.
• Minimization of system errors through close fiber spacing and reflective structures.

Conclusions:

• The proposed DOF-HPSPDI is a feasible, stable, and cost-effective solution for high-precision optical testing.
• This compact interferometer shows significant promise for advanced optical metrology and manufacturing applications.