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Abstract:

A widely tested approach to overcoming the diffraction limit in microscopy without disturbing the sample relies on substituting widefield sample illumination with a structured light beam. This gives rise to confocal, image scanning, and structured illumination microscopy methods. On the other hand, as shown recently by Tsang and others, subdiffractional resolution at the detection end of the microscope can be achieved by replacing the intensity measurement in the image plane with spatial mode demultiplexing. In this work, we study the combined action of Tsang’s method with image scanning. We experimentally demonstrate superior lateral resolution and enhanced image quality compared to either method alone. This result paves the way for integrating spatial demultiplexing into existing microscopes, contributing to further pushing the boundaries of optical resolution.

Abstract:

The need to observe objects that are smaller than the diffraction limit has led to the development of various superresolution techniques. However, most such techniques require active interaction with the sample, which may not be possible in multiple practical scenarios. The recently developed technique of Hermite–Gaussian imaging (HGI) achieves superresolution by passively observing the light coming from an object. This approach involves decomposing the incoming field into the Hermite–Gaussian basis of spatial modes and measuring the amplitude or intensity of each component. From these measurements, the original object can be reconstructed. However, implementing HGI experimentally has proven to be challenging, and previous achievements have focused on coherent imaging or parameter estimation of simple objects. In this paper, we implement interferometric HGI in the incoherent regime and demonstrate a three-fold improvement in the resolution compared to direct imaging. We evaluate the performance of our method under different noise levels. Our results constitute a step towards powerful passive superresolution imaging techniques in fluorescent microscopy and astronomy.