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Real-time detection of NAD(P)H is particularly important for understanding physiological activities of neutrophils. We scrutinize the performance of weak light detection systems with electron multiplying CCDs (EMCCDs) with regard to the feasibility of valid investigations by autofluorescence NAD(P)H in single human neutrophils. The low-noise amplification facility of EMCCDs is indeed just adequate to permit detection at an irradiation level where neither quenching nor phototoxic effects occur. For demonstration, a neutrophil respiratory burst was triggered and observed in real time. Our low-intensity detection system fulfills all requirements for real-time investigations at high spatiotemporal resolution in the field of neutrophil physiology and pathology. OCIS codes: 170.3880, 110.2970, 260.2510.

Generation and evolution of plasma during femtosecond laser ablation of silicon are studied by steady-state and time-resolved spectroscopy in air, N2, SF6, and under vacuum. The plasma is generated faster than 200 ps (time resolution of our experiment) after excitation and mainly contains atoms and monovalent ions of silicon. Time-resolved spectra prove that silicon ions are faster than the silicon atoms which may be attributed to Coulomb repulsion and a local electric field when they are ejected from the silicon surface. During plasma evolution, ambient gas causes a confinement effect that enhances the dissociation of ambient gas molecules and the re-deposition of the removed material and leads to higher intensity and longer lifetime of the emission spectra. In SF6, a chemical reaction increases the plasma density and weakens the re-deposition effect. The different processes during plasma evolution strongly influence microstructure formation. [ABSTRACT FROM PUBLISHER]

We investigated the light-induced backward scattering in doubly doped lithium niobate crystals and observed an intensity threshold effect. It will be shown that scattering microregions are locally recorded in the sample by holographic interaction due to the existence of the threshold effect. Experimental results of multilayer recording point out that this property could be used for high-density multilayer-like bit data optical storage while keeping high signal-to-noise ratio. [ABSTRACT FROM AUTHOR]