Multi-azimuthal illumination total internal reflection microscopy based on dual wedge prism design.

Area of Science:

• Optical Microscopy
• Nanotechnology
• Biophysics

Background:

• Label-free microscopy techniques are crucial for observing unstained biological and nanomaterials.
• Total internal reflection microscopy (TIRM) offers high resolution near the coverslip but is often limited by directional illumination.
• Evanescent wave (EW) illumination in TIRM can be challenging to control across all azimuthal angles.

Purpose of the Study:

• To develop a high-quality, label-free total internal reflection microscopy method with multi-azimuthal evanescent wave illumination.
• To achieve uniform polarization control for evanescent waves at all azimuthal angles.
• To demonstrate the system's capability for high-resolution imaging of challenging samples.

Main Methods:

• A novel dual wedge prism (WP) design was employed to generate evanescent waves.
• Sequential rotation of the wedge prisms allowed excitation of evanescent waves with all-directional wave vectors.
• Integration of a half-wave plate (HWP) ensured consistent polarization directions of the evanescent waves across all azimuthal angles.

Main Results:

• The proposed dual WP design enables multi-azimuthal EW illumination, overcoming single-direction limitations.
• High-fidelity and high-resolution structures of fabricated resolution test targets were successfully resolved.
• Detailed imaging of silver nanowire (NW) samples, previously unresolved, was achieved.

Conclusions:

• The dual wedge prism design provides a simple, cost-effective, and user-friendly approach for advanced TIRM.
• This method significantly enhances imaging resolution and fidelity compared to conventional single-direction TIRM.
• The technique holds promise for detailed nanoscale imaging in various scientific fields.