Varifocal Metalens for Optical Sectioning Fluorescence Microscopy

Fluorescence microscopy with optical sectioning capabilities is extensively utilized in biological research to obtain three-dimensional structural images of volumetric samples. Tunable lenses have been applied in microscopy for axial scanning to acquire multiplane images. However, images acquired by conventional tunable lenses suffer from spherical aberration and distortions. Here, we design, fabricate, and implement a dielectric Moire metalens for fluorescence imaging. The Moire metalens consists of two complementary phase metasurfaces, with variable focal length, ranging from similar to 10 to similar to 125 mm at 532 nm by tuning mutual angles. In addition, a telecentric configuration using the Moire metalens is designed for high-contrast multiplane fluorescence imaging. The performance of our system is evaluated by optically sectioned images obtained from HiLo illumination of fluorescently labeled beads, as well as ex vivo mice intestine tissue samples. The compact design of the varifocal metalens may find important applications in fluorescence microscopy and endoscopy for clinical purposes.

Automated summary

A dielectric Moire metalens is designed, fabricated, and implemented for fluorescence imaging with varifocal capabilities, utilizing two complementary phase metasurfaces with adjustable focal length through mutual angle tuning. The compact design may have important applications in clinical fluorescence microscopy and endoscopy.