Interscale mixing microscopy: numerically stable imaging of wavelength- scale objects with sub-wavelength resolution and far field measurements.

Sandeep Inampudi,Viktor A Podolskiy,Nicholas Kuhta

doi:10.1364/oe.23.002753

Abstract

We present an imaging technique that allows the recovery of the profile of wavelength-scale objects with deep subwavelength resolution based on far-field intensity measurements. The approach, interscale mixing microscopy (IMM), relies on diffractive elements positioned in the near-field proximity of an object in order to scatter information carried by evanescent waves into propagating part of the spectrum. A combination of numerical solutions of Maxwell equations and nonlinear fitting is then used to recover the information about the object based on far-field intensity measurements. It is demonstrated that IMM has the potential to recover wavelength/20 features of wavelength-scale objects in the presence of 10% noise.

Highlights

Numerous applications in materials, device characterization, security and biology require imaging with subwavelength resolution[1, 2, 3, 4]
We present an imaging technique that allows the recovery of the transparency profile of wavelength-scale objects with deep subwavelength resolution based on far-field intensity measurements
The approach, interscale mixing microscopy (IMM), relies on diffractive element positioned in the near-field proximity to the object, to scatter information carried by evanescent waves into propagating part of the spectrum

Summary

Introduction

Device characterization, security and biology require imaging with subwavelength resolution[1, 2, 3, 4]. Diffraction-imaging techniques capable of deep subwavelength resolution based on far-field field[16] and intensity[17] measurements of have been recently proposed. In the latter approach, interscale mixing microscopy (IMM), the object is positioned in the near-field proximity to diffraction element that outcouples information about subwavelength features of the object to the far field where it can be detected by conventional means, followed by computational reconstruction of the object. While there is no fundamental limit on coupling between different parts of the spectrum, accuracy and resolution of the final image and the robustness of the technique are dependent on i) the efficiency and stabilty of the diffraction element to couple the spectrum, and ii) the efficiency of employed computational optimization techniques to un-couple the spectrum and cope with the noise in the measurement data[12]. We aim to resolve λ /20 features of ∼ λ -sized objects

IMM with periodic diffraction elements

Findings

Conclusion