Improved resolution Fourier ptychography scheme using oil‐filled dome‐shaped LED array

Abstract

Abstract Utilising angular‐varied illumination in Fourier Ptychography, the resolution of optical microscopes can be increased and the phase of the sample can also be recovered while maintaining a wide field‐of‐view. In this work, an Fourier Ptychography microscopy imaging setup is demonstrated using a 10X 0.28 NA objective lens and a dome‐shaped light‐emitting diode array illuminator. By increasing the refractive index of the medium between the sample and light sources using oil filled dome, a synthetic system numerical aperture of 0.68 is achieved using only 37 light‐emitting diodes. The measured resolution of 345 nm at a wavelength of 530 nm closely matches the theoretical prediction. Furthermore, the results of the oil‐medium illumination are compared to free‐space illumination. The oil immersion on the illumination side effectively enhances the illumination numerical aperture as compared to air and reduces the need for far off‐axis light‐emitting diodes. The result is high‐resolution Fourier Ptychography imaging with relatively fewer light‐emitting diodes providing both short capture and reconstruction times.