977 research outputs found
Complementary Speckle Patterns : deterministic interchange of intrinsic vortices and maxima through Scattering Media
Intensity minima and maxima of speckle patterns obtained behind a diffuser
are experimentally interchanged by applying a spiral phase delay of charge to the impinging coherent beam. This transform arises from the intuitive
expectation that a tightly focused beam is so-changed into a vortex beam and
vice-versa. The statistics of extrema locations and the intensity distribution
of the so-generated "complementary" patterns are characterized by numerical
simulations. It is demonstrated experimentally that the incoherent
superposition of the three "complementary speckle patterns" yield a synthetic
speckle grain size enlarged by a factor . A cyclic permutation of
optical vortices and maxima is unexpectedly observed and discussed.Comment: 9 pages, 9 figure
Compressive Raman imaging with spatial frequency modulated illumination
We report a line scanning imaging modality of compressive Raman technology
with spatial frequency modulated illumination using a single pixel detector. We
demonstrate the imaging and classification of three different chemical species
at line scan rates of 40 Hz
Nonlinear imaging through a golden spiral multicore fiber
We report two-photon lensless imaging through a novel golden spiral multicore
fiber. This unique layout optimizes the sidelobe levels, field of view,
cross-talk, group delay and mode density to achieve a sidelobe contrast of
atleast 10.9 dB. We demonstrate experimentally the ability to generate and scan
a focal point with a femtosecond pulse and perform two-photon imaging.Comment: Submitted to Optics Letter
Photonic Methods to Enhance Fluorescence Correlation Spectroscopy and Single Molecule Fluorescence Detection
Recent advances in nanophotonics open the way for promising applications towards efficient single molecule fluorescence analysis. In this review, we discuss how photonic methods bring innovative solutions for two essential questions: how to detect a single molecule in a highly concentrated solution, and how to enhance the faint optical signal emitted per molecule? The focus is set primarily on the widely used technique of fluorescence correlation spectroscopy (FCS), yet the discussion can be extended to other single molecule detection methods
A versatile dual spot laser scanning confocal microscopy system for advanced fluorescence correlation spectroscopy analysis in living cell
A fluorescence correlation spectroscopy (FCS) system based on two independent
measurement volumes is presented. The optical setup and data acquisition
hardware are detailed, as well as a complete protocol to control the location,
size and shape of the measurement volumes. A method that allows to monitor
independently the excitation and collection efficiency distribution is
proposed. Finally, a few examples of measurements that exploit the two spots in
static and/or scanning schemes, are reported.Comment: Accepted for publication in Review of Scientific Instrumen
- …