High-magnification super-resolution FINCH microscopy using birefringent crystal lens interferometers

Area of Science:

• Biomedical Optics
• Microscopy
• Cell Biology

Background:

• Fresnel incoherent correlation holography (FINCH) microscopy offers high-resolution imaging potential.
• Previous FINCH implementations were limited to low-magnification and low-numerical-aperture configurations, hindering broader applications.
• Aberrations and distortions affected image quality in earlier FINCH systems.

Purpose of the Study:

• To develop and validate a novel FINCH microscopy system capable of high-numerical-aperture imaging.
• To overcome the limitations of previous FINCH microscopy setups by employing birefringent elements.
• To demonstrate enhanced resolution and image quality for biological samples.

Main Methods:

• Utilized in-line incoherent interferometers constructed from uniaxial birefringent crystals (α-barium borate or calcite).
• Integrated these birefringent elements with high-numerical-aperture oil immersion objectives.
• Validated resolution using sub-resolution fluorescent beads and imaging of labeled proteins in HeLa cells.

Main Results:

• Achieved a lateral point spread function of 149 nm at a 590 nm wavelength, surpassing standard wide-field fluorescence microscopy.
• Successfully resolved three different GFP-labeled proteins and two other fluorescent dyes within the Golgi apparatus of HeLa cells.
• Demonstrated image quality comparable to structured illumination microscopy for complex biological samples.

Conclusions:

• Novel birefringent elements significantly enhance FINCH microscopy performance, overcoming previous aberration issues.
• The improved FINCH system enables high-resolution imaging of subcellular structures with excellent detail.
• This advancement positions FINCH microscopy as a powerful tool for detailed biological investigation.