Evaluation of optical aberrations in point images

Area of Science:

• Optics
• Optical Engineering
• Image Quality Assessment

Background:

• Merit figures for optical systems differ based on whether ray or wave-front aberrations are considered.
• Understanding the transition between physical and geometrical optics is crucial for accurate optical design.
• Zernike polynomials and wave-front slope-based orthogonal polynomials offer distinct approaches to aberration analysis.

Purpose of the Study:

• To investigate the transition from physical optics to geometrical optics using different aberration analyses.
• To compare merit figures derived from ray aberrations versus wave-front aberrations.
• To establish a consistent measure of image quality across different optical regimes.

Main Methods:

• Utilized Zernike polynomials and orthogonal polynomials based on wave-front slope.
• Employed a knife-edge energy distribution to evaluate point images from both physical and geometrical optics.
• Analyzed parameters like major axis radius and irradiance distribution eccentricity.
• Performed a direct comparison of geometrical and physical aberrations up to tenth order using geometrical-physical spot size.

Main Results:

• Ray aberration-based merit figures yield different results compared to wave-front aberration-based ones.
• Knife-edge scans provide a consistent measure of spot size for both geometrical (spot diagrams) and physical (diffraction) optics.
• Spot size is a valid figure of merit, applicable even at the diffraction limit.
• Direct comparison shows consistency in image quality assessment between the two optical domains.

Conclusions:

• Spot size, determined via knife-edge scans, serves as a reliable and consistent figure of merit for optical image quality.
• This measure is valid across the transition region between geometrical and physical optics, extending to the diffraction limit.
• The study bridges the gap between geometrical and physical optics by validating a common metric for aberration assessment.