Low-cost 3D-printed optics for super-resolution multifocal structured illumination microscopy

We present a low-cost 3D-printing method of fabricating optical quality lenslet arrays for integration in a multifocal structured illumination microscope (mSIM), achieving super-resolution fluorescence imaging using 3D-printed optics for the first time. We detail the design and manufacturing processes to produce high-quality 3D-printed optics, showing their comparable surface roughness of 30 ± 2.5 nm for the 3D-printed elements compared to 37 ± 1.4 nm for commercial glass optics. A 3D-printed lenslet array with a 'honeycomb' geometry and 1.2 mm lenslet diameter was compared to a high-end glass commercial lenslet array with 250 µm lenslet diameter and a lower cost commercial lenslet array with a 1 mm by 1.4 mm lenslet footprint. The imaging performance of the different optics was benchmarked using a custom mSIM setup by quantifying the beam profile homogeneity and the experimental lateral resolution. The mSIM setup incorporating the different microlens arrays was tested using a commercial bovine pulmonary artery endothelial cell specimen, highlighting an achievable resolution enhancement from 237 nm ± 12 nm with laser-scanning illumination to 151 ± 12 nm using the high-end commercial microlens array and from 232 ± 18 nm with laser-scanning illumination to 151 nm ± 12 nm using the 3D-printed honeycomb lenslet array. Advantages of improved background rejection through the custom lenslet geometry are discussed, highlighting the super-resolution microscope performance achievable using custom 3D-printed optics costing as low as £0.50 to produce.