Spoke wheel filtering strategy for on-axis flattop shaping

Area of Science:

• Optics and Photonics
• Optical Engineering
• Image Processing

Background:

• Traditional pupil filters often suffer from significant intensity oscillations and limited focal depth control.
• The need for advanced optical filtering strategies is crucial for enhancing imaging resolution and depth.
• Super-Gaussian functions offer potential for novel filter designs with tailored optical properties.

Purpose of the Study:

• To develop a novel spoke wheel filter (SWF) for improved optical filtering.
• To investigate the impact of SWF design parameters on focal depth and intensity oscillations.
• To compare the performance of SWF against existing radial-symmetric pupil filters.

Main Methods:

• Development of a spoke wheel filter (SWF) based on a nonlinear optimization model.
• Introduction of a super-Gaussian function to define the filter's characteristics.
• Utilizing a simulated annealing algorithm for theoretical calculations and parameter optimization.

Main Results:

• Increased number of curved sectors in SWF leads to a higher focal depth.
• Appropriate bending and amplitude transmittance adjustments reduce peak-valley intensity oscillation.
• Enlarging the center-shaded circle of SWF results in transverse in-focus spot compression.

Conclusions:

• The proposed spoke wheel filter (SWF) demonstrates superior performance compared to radial-symmetric filters.
• SWF offers significantly reduced intensity oscillation and highly flexible control over focal depth extension.
• This strategy provides a promising approach for advanced optical system design and performance enhancement.