Rapid Cellular-Resolution Skin Imaging with Optical Coherence Tomography Using All-Glass Multifocal Metasurfaces

Area of Science:

• Biomedical Optics
• Optical Engineering
• Materials Science

Background:

• Cellular-resolution optical coherence tomography (OCT) provides noninvasive histology-like imaging.
• High numerical aperture (N.A.) lenses in OCT limit imaging speed due to narrow depth of field, requiring dynamic focusing.

Purpose of the Study:

• To develop a metasurface platform for generating multiple axial foci to overcome OCT's depth-of-field limitation.
• To enhance volumetric OCT imaging speed for applications like rapid virtual biopsy.

Main Methods:

• Fabrication of all-glass metasurface optical elements from fused-silica wafers.
• Integration of the metasurface into a scanning OCT system to create multifocal beams.
• Evaluation of lateral resolution and volumetric acquisition speed in dermatological imaging.

Main Results:

• The metasurface platform enables flexible control over the number, position, and intensity of axial foci.
• A constant lateral resolution of 1.1 μm was maintained across all depths.
• Volumetric OCT imaging speed was tripled for dermatological imaging, with potential for 7-fold improvement.
• Distinct visualization of skin layers and diagnostic features for basal cell carcinoma was achieved.

Conclusions:

• Metasurface-based multifocal OCT significantly accelerates volumetric imaging for noninvasive virtual biopsies.
• This technology offers high resolution and compact imaging system potential.
• The approach provides valuable morphological information for dermatological diagnostics.