Two-photon scanning fluorescence microscopy has become a powerful tool for imaging living cells and tissues. Most applications of two-photon microscopy employ a Ti:sapphire laser excitation source, which is not readily portable or rapidly tunable. This work explores the use of two-photon fiber laser excitation (TP-FLEX) as an excitation source for scanning two-photon microscopy. We have further...

In this paper, I consider theoretical models of the decay via photobleaching of a sample of surface-immobilized fluorescent molecules excited by a spatially varying laser intensity profile. I show that, with mild restrictions on the photobleaching mechanism, the fluorescence decay measured in a nonuniform excitation profile is always nonexponential. Under the same conditions, the fluorescence d...

Photophysical parameters and lasing properties of Coumarin 540A dye molecules are studied in solutions of increasing viscosity, from liquid solutions in 1,4-dioxane to solid solutions in poly~methyl methacrylate!. The fluorescence quantum yield and lasing efficiencies decrease as the viscosity of the solution increases, reflecting the strong influence of the rigidity of the medium on the radiat...

A novel technique, designated dual imaging and modeling evaluation (DIME), for evaluating single-laser shot fluorescence lifetimes is presented. The technique is experimentally verified in a generic gas mixing experiment to provide a clear demonstration of the rapidness and sensitivity of the detector scheme. Single-laser shot fluorescence lifetimes of roughly 800 ps with a standard deviation o...

The acid resistance of Nd:YAG laser-ablated enamel surfaces was studied by evaluating crystal structure, mineral distribution, and fluorescence radiance and image in the present study. For comparison, 37% phosphoric acid etching was performed. The formation of beta-tricalcium phosphate (beta-TCP) was confirmed in the laser-ablated surface. The Ca/P ratio increased after ablation due to mineral ...

An ultrasound coupled handheld-probe-based optical fluorescence molecular tomography (FMT) system has been in development for the purpose of quantifying the production of Protoporphyrin IX (PPIX) in aminolevulinic acid treated (ALA), Basal Cell Carcinoma (BCC) in vivo. The design couples fiber-based spectral sampling of PPIX fluorescence emission with a high frequency ultrasound imaging system,...

The effect of dimethoate on the photosynthetic activity and pigments content on Cajanus cajan L. is determined by laser induced chlorophyll fluorescence (LICF) and fluorescence induction kinetics (FIK) of leaves. The LICF spectra is recorded in the region of 650-780 nm by using 405 nm violet diode laser and FIK curves are recorded at 685 and 730 nm by using 635 nm red diode laser as the excitat...

Laser-induced fluorescence (LIF) is a spectroscopic technique that involves the excitation of a molecular target by a beam of laser radiation followed by the detection of the subsequent emission of radiation from the target. LIF detection has several advantages over absorption spectroscopy. First, LIF has excellent detection sensitivity because a signal is observed against a dark background. Se...

Laser induced fluorescence is used to develop a 2D measurement technique for mixture formation analysis of fuel and air in a broad temperature regime from 398 K up to 548 K. The measurement principle is called FARLIF (fuel-air ratio by laser-induced fluorescence). Its application is tested on the tracer toluene in the non-fluorescent model fuel isooctane as well as on an auto-fluorescing nearst...

Plastic materials have the potential to substitute for glass substrates used in microfluidic and microTAS systems adding flexibility in materials' choices. Optical quality plastic materials with a low autofluorescence are crucial for optimal detection by fluorescence and laser induced fluorescence techniques. This paper summarizes a series of optical investigations on commercially available pla...