Classical imaging theory of a microlens with super-resolution

Area of Science:

• Optics and Photonics
• Nanotechnology
• Imaging Science

Background:

• Super-resolution imaging with transparent spherical microlenses has demonstrated significant resolution improvements.
• Previous explanations for this phenomenon primarily relied on the photonic nanojet super-focusing effect.
• Direct imaging calculations using classical imaging theory have been underexplored.

Purpose of the Study:

• To theoretically model the imaging process through a spherical microlens.
• To investigate the physical mechanisms behind experimentally observed super-resolution.
• To evaluate the validity of the photonic nanojet explanation within classical imaging theory.

Main Methods:

• Vectorial electromagnetic analysis was employed to model the microlens imaging process.
• Classical imaging theory, specifically the two-point resolution criterion, was applied.
• Theoretical calculations were performed to assess resolution limits.

Main Results:

• The study excluded the super-focusing effect of photonic nanojets as the sole explanation for super-resolution.
• Classical imaging theory, under the two-point resolution criterion, indicates that a perfect spherical microlens cannot achieve sub-100 nm resolution.
• The experimentally verified resolution surpasses the theoretical limits predicted by classical models.

Conclusions:

• The photonic nanojet super-focusing effect does not fully account for the observed super-resolution in microlens imaging.
• Classical imaging theory, as applied, is insufficient to explain the experimentally achieved sub-100 nm resolution.
• Unidentified physical mechanisms are likely responsible for the ultrahigh resolution reported in experimental studies.