Nonparaxial aberrations in the optical Talbot effect probed by quantum-dot fluorescence tomography

Abstract

The Talbot effect is a near-field phenomenon of a coherent wave transmitted through a grating to form self-images at distances of integer multiples of the so-called Talbot length. However, at long distances, the higher-order diffraction waves fail to converge and spatial walk-off aberration occurs. Here, we describe a scheme for measuring the optical Talbot effect including the spatial walk-off aberration. Our approach utilizes a quantum dot fluorescent film as a tomographic means to probe the Talbot intensity patterns. Since the Talbot effect itself is based on diffraction and interference, measuring it with conventional microscopy systems with a limited acceptance angle might not allow for covering aberrations introduced by walk-off effects. The experiment demonstrates that, by utilizing the fluorescent film as an intermediate step and imaging the fluorescence instead, rather than imaging the intensity patterns directly, higher resolution can be achieved and effects not covered by the numerical aperture of the microscope objectiveused for imaging can be observed.