Angle spread function degradation by surface roughness in imaging optics

Area of Science:

• Optics
• Optical Engineering
• Surface Science

Background:

• Surface roughness degrades the performance of imaging optical systems.
• Existing models often rely on approximations for surface roughness effects.

Purpose of the Study:

• Derive a formula for the total width of the angle spread function in systems with surface roughness.
• Investigate the contribution of scattering from surface roughness without small roughness approximations.

Main Methods:

• Utilized the scalar theory of diffraction.
• Developed a derivation not limited by the small roughness approximation.

Main Results:

• The contribution of scattering from surface roughness depends solely on the variance of the roughness slope.
• Identified an inaccuracy in the common method of calculating the total angle spread function width.

Conclusions:

• A novel formula for angle spread function width is established.
• The variance of roughness slope is a critical parameter for understanding scattering effects.
• The conventional square-sum rule for combining scattering and specular components is shown to be inadequate.