Rigid and high-numerical-aperture two-photon fluorescence endoscope

We present a rigid miniaturized optical system block fiber-optic two-photon endoscope based on a compact two-axis piezo scanner system and a miniature high (0.65) NA GRIN lens objective. The optical system is scanned as a whole by a piezo scanner allowing always an on-axis beam irradiation of the optical system. A photonic crystal fiber is used for excitation and ultrashort laser pulses can be delivered with typical power up to 100 mW at 800 run. Two-photon fluorescence signal is collected by the use of a multimode fiber. Lateral resolution values for the system were experimentally measured to be 0.67 mu m vertically and 1.08 mu m horizontally. Axial resolution was found to be 5.8 mu m. The endoscope is highly flexible and controllable in terms of time acquisition, resolution, and magnification. Fluorescence images were acquired over a 420 mu m x 420 mu m field of view. Results presented here demonstrate the ability of the system to resolve subcellular details and the potential of the technology for in vivo applications

5 W à 255 nm et 15 kHz obtenus par doublage de fréquence d'un laser CuHBr dans du BBO

5.1 W de rayonnement ultra-violet ont été obtenus à 15 kHz par doublage de fréquence de la raie à 510.6 nm d'un laser CuHBr dans deux cristaux de BBO. La qualité de faisceau du rayonnement UV est exprimée par le paramètre $M^2 : M_X^2 = 30\pm 2$ et $M_Y^2= 24 \pm 2$. Les deux faisceaux UV issus des deux cristaux de BBO, combinés au point focal d'une lentille, permettent le micro-usinage UV à haute cadence

Large-area, uniform, high-spatial-frequency ripples generated on silicon using a nanojoule-femtosecond laser at high repetition rate

Large-area high-spatial-frequency patterns (HSFLs) of /6 periodicity have been generated by a nanojoule-femtosecond laser scanning technique (80MHz, 170 fs, 700-950nm) at the silicon-air interface. The excellent large-area uniformity allowed reproducible and accurate measurements of the periodicity. Variation of experimental parameters as illumination geometry, and pulse energy and number showed no influence on the ripple spacing. A wavelength dependence was observed and compared to current models of HSFL formation. A particular second- armonic model was found to match the results best but needs to take into account transient changes in the refractive index under laser exposure. A second-harmonic mechanism is further supported by direct spectroscopic observation

High (1 GHz) repetition rate compact femtosecond laser: A powerful multiphoton tool for nanomedicine and nanobiotechnology

Multiphoton tomography of human skin and nanosurgery of human chromosomes have been performed with a 1 GHz repetition rate laser by the use of the commercially available femtosecond multiphoton laser tomograph DermaInspect as well as a compact galvoscanning microscope. We performed the autofluorescence tomography up to 100 mu m in the depth of human skin. Submicron cutting lines and hole drillings have been conducted on labeled human chromosomes