Jerome Wenger NanoBioPhotonics

See the paper by Lynn Savage in the July issue on the recent work of “Patrick Ferrand and colleagues at the Fresnel Institute” :

http://www.photonics.com/content/spectra/2008/July/microscopy/92560.aspx

This trimester’s selection is pretty short (sorry, I’m in a rush to finish several research projects). I pointed out a contribution of Jordan Gerton’s team in Optics Express :

http://www.opticsinfobase.org/abstract.cfm?URI=oe-16-9-6183

The papers points out a nice theoretical and experimental study on the limits of single-molecule fluorescence detection within a dense ensemble, using tip-enhanced near-field microscopy. Specifically, the minimum magnitude of tip-induced signal enhancement is discussed and compared to the capabilities of commercially available silicon tips. Last, the authors show that modulation of fluorescence signals induced by an oscillating tip followed by demodulation with a lock-in amplifier increases image contrast by nearly two orders of magnitude.

Back from the first French-Taiwanese symposium on Frontiers of Sciences, which was held in Taiwan from 25^th to 29^th of June this year. I’m very pleased to have attended this stimulating exchange. Taking some distance from the everyday’s lab work is always fruitful, specifically to think about the way of presenting the research work : what is the problematic, what is the goal ? I often forget about both questions, conferences help keeping connected with these issues.

Published recently in Optics Express, it’s freely available at :
http://www.opticsinfobase.org/abstract.cfm?URI=oe-16-10-6930

We investigate the focusing of light by single latex microspheres illuminated by a collimated beam. Measurements are performed with a fast scanning confocal microscope in detection mode, where the detection pinhole defines a diffraction-limited observation volume that is scanned in three dimensions over the microsphere vicinity. From the collected stack of images, we reconstruct the full 3 dimensional photonic nanojet beam created by the microsphere.

Remarkably, we measure spot sizes as small as 270 nm FWHM for a wavelength of 520 nm. The beam keeps a subwavelength FWHM over a propagation distance of more than 3 micrometers, displaying all the specificities of a photonic nanojet. 

Click on the video below to visualize the photonic nanojet :