Structured illumination fluorescence microscopy with distorted excitations using a filtered blind-SIM algorithm.

Structured illumination microscopy (SIM) is a powerful technique for obtaining super-resolved fluorescence maps of samples, but it is very sensitive to aberrations or misalignments affecting the excitation patterns. Here, we present a reconstruction algorithm that is able to process SIM data even if the illuminations are strongly distorted. The approach is an extension of the recent blind-SIM technique, which reconstructs simultaneously the sample and the excitation patterns without a priori information on the latter. Our algorithm was checked on synthetic and experimental data using distorted and nondistorted illuminations. The reconstructions were similar to that obtained by up-to-date SIM methods when the illuminations were periodic and remained artifact-free when the illuminations were strongly distorted.

Scanning-less wide-field single-photon counting device for fluorescence intensity, lifetime and time-resolved anisotropy imaging microscopy.

A scanning-less single-photon counting system for FLIM and fluorescence anisotropy wide-field imaging is described and characterized in this paper. The two polarizations of the fluorescence are divided by a Glan prism and acquired at the same time by the Q(A) detector. Fluorescence decay profiles can be reconstructed for any desired area up to each pixel and used to calculate time-resolved fluorescence anisotropy decays.

Coherent anti-Stokes Raman scattering (CARS) microscopy imaging at interfaces: evidence of interference effects.

We show in this paper that the contrast of the interface between resonant and nonresonant media imaged in Coherent anti-Stokes Raman scattering (CARS) microscopy strongly depends on the pump and Stokes fields spectral detuning. More specifically, when this detuning drives the vibrational resonance with the maximum phase difference, a spatial dip appears at the interface in the CARS image. This effect is studied both theoretically and experimentally and is an evidence of the coherent and resonant nature of the CARS contrast mechanism.

Defocused imaging of second harmonic generation from a single nanocrystal.

We demonstrate the direct imaging of the second harmonic generation radiation from a single nonlinear nanocrystal using defocused nonlinear microscopy. This technique allows the retrieval of complete information on the 3D orientation of a nanocrystal as well as possible deviations from its purely crystalline nature, in a simple experimental implementation. The obtained images are modeled by calculation of the radiation diagram from a nonlinear dipole that accounts for the excitation beam, the crystal symmetry and the particle size. Experimental demonstrations are performed on Potassium Titanyl Phosphase (KTP) nanocrystals. The shape and structure of the radiation images show a strong dependence on both crystal orientation and field polarization state, as expected by the specific nonlinear coherent coupling between the induced dipole and the excitation field polarization state.