Compact radial shearing interferometer with a randomly encoded cosinusoidal zone plate for wavefront measurements

Area of Science:

• Optics and Photonics
• Interferometry
• Wavefront Sensing

Background:

• Traditional interferometers face limitations in dynamic range and sensitivity.
• Wavefront measurement is crucial for optical system characterization and correction.

Purpose of the Study:

• To propose and validate a new radial shearing interferometer (RSI) based on a randomly encoded cosinusoidal zone plate (RECZP).
• To investigate the influence of various errors on the performance of the RECZP-RSI system.
• To demonstrate the system's capability for accurate wavefront measurement.

Main Methods:

• Development of a radial shearing interferometer (RSI) employing a randomly encoded cosinusoidal zone plate (RECZP).
• Simulation experiments to analyze the impact of beam tilt, distance errors, CCD nonlinearity, and noise.
• Analysis of fabrication errors on diffraction intensity and RECZP tolerance.
• Experimental comparison with a commercial ZYGO interferometer.

Main Results:

• The RECZP-RSI system successfully generates two beams (extended and contracted) essential for radial shearing.
• Continuously adjustable radial shearing rate achieved by varying the distance between the RECZP and CCD.
• Simulation identified key error sources affecting wavefront reconstruction accuracy.
• Fabrication error analysis provided insights into RECZP manufacturing tolerances.
• Experimental results demonstrated comparable performance to a ZYGO interferometer.

Conclusions:

• The proposed RECZP-RSI is a viable and effective tool for wavefront measurement.
• The system's adjustable shearing rate enhances its adaptability and measurement capabilities.
• Understanding error sources and fabrication tolerances is critical for optimizing RECZP-RSI performance.