Search

In this study, a novel optical super-resolution imaging technique, grating and deep neural network assisted super-resolution microscopy, is proposed. The technique utilizes a sub-wavelength grating, placed between the sample and the microscope objective, to convert the evanescent waves of a sample surface into propagating waves, allowing more high spatial-frequency information of the sample to be detected in the far field. Then, the far-field image of the sample is captured and trained end-to-end with a customized deep neural network model to heuristically reconstruct a clear image of the sample with structural features smaller than λ/3. Compared with the existing super-resolution imaging techniques, the proposed technique has the advantages of label-free, large field of view, one-time direct imaging, and white light illumination and observation in an atmospheric environment. Moreover, it has the flexibility to replace raster and network rendering components according to specific inspection requirements to meet diverse application scenarios. [ABSTRACT FROM AUTHOR]

Waveguide-based total internal reflection fluorescence microscopy has been widely adopted due to its excellent signal-to-noise ratio over a large field of view. However, with the increasing demand for label-free imaging, waveguide-based evanescent light scattering microscopy (ESM) has also garnered significant attention. Here, we present a low-cost waveguide-based microscope slide that offers easier integration with conventional optical microscopy. This microscope slide uses an incoherent light source coupled to a lithium tantalate (LT) planar waveguide to generate an evanescent light that illuminates samples located within a few hundred nanometers of the waveguide surface. We perform its application for imaging chromium nanoholes and polystyrene nanospheres, demonstrating its label-free, high-resolution, high-contrast imaging performance. LT waveguide microscope slides provide a simple and effective solution for ESM. [ABSTRACT FROM AUTHOR]

There is an increasing demand for label‐free imaging of subwavelength low‐index dielectric samples with high contrast and high sensitivity using a dark‐field optical microscope. However, subwavelength low‐index dielectric samples usually do not show strong Mie scattering resonance characteristics due to the weak light confining ability, which makes them difficult to clearly resolve under a traditional optical microscope. In this work, a fast, simple, and effective approach is proposed to enhance the optical response of subwavelength low‐index dielectric samples by using metallic substrate‐enhanced scattering nanoscopy. It is found that the high reflectance of a substrate can significantly enhance the electric dipole resonance of a SiO2 nanoparticle and the substrate‐nanoparticle interaction, which amplifies the scattering signal of the sample and improves the imaging contrast. Compared with the silica substrate, the Ag‐coated substrate can enhance the scattering intensity of a SiO2 nanoparticle up to 3.7 times under 540 nm wavelength illumination. Furthermore, label‐free stand‐alone 50‐nm‐radius SiO2 nanoparticles and ≈100‐nm‐thick bacterial capsules can be clearly observed when placed on Ag‐coated substrates under a conventional dark‐field optical microscope. The substrate‐enhanced subwavelength‐resolution scattering nanoscopy can enhance the scattering of low‐index subwavelength samples and benefit a significant application in biology, medical testing, and optical detection. [ABSTRACT FROM AUTHOR]

Using a two-dimensional hexagonally close-packed SiO2/Ag nanoshell array coated with or without a dielectric layer as an imaging object, we find that the imaging quality of microsphere-assisted microscopy depends strongly on the optical properties of the metallodielectric sample. When a thin dielectric film is deposited on the top surface of a SiO2/Ag nanoshell array, a periodic enhanced near-field electric field is formed at the interface between the Ag layer and the deposited dielectric layer due to the excitation of surface plasmon polaritons. By increasing the dielectric constant of the coating layer, the enhanced near-field electric field region becomes larger and extends into the region which is closer to the imaging system. When the SiO2/Ag nanoshell array is coated with a SiO layer, the best resolution, the highest magnification, and the longest working distance are obtained. And, a SiO coated nanoshell array with a core size of 180 nm (λ/3, where λ = 540 nm is the central wavelength of illumination) can be resolved. [ABSTRACT FROM AUTHOR]

Research is presented into the effect of density of Ge nanocrystals on violet-blue photoluminescence of Ge+-implanted SiO2 film.