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We report the development of an efficient and compact neodymium-doped yttrium aluminium garnet (Nd-YAG) laser for eye microsurgery. High efficiency and excellent multimode beam quality were obtained by use of a reflecting close-coupled cavity. Stable and unstable resonator configurations were compared. Some experiments performed with this laser are presented and discussed. [ABSTRACT FROM AUTHOR]

Continuous wave and time-resolved fluorescence microscopy have been extensively used to characterize the behaviour of haematoporphyrin derivative (HPD) both in solution and in single cells. In this work, we report experimental evidence for the presence of a 580 nm-emitting species, occurring as a consequence of modifications in HPD induced by the cellular microenvironment. The fact that the formation of this 'modified' species seems to be favoured in tumour cells might increase sensitivity in the diagnostic use of HPD for the localization of early-stage tumours. [ABSTRACT FROM AUTHOR]

In this paper we describe a simple and inexpensive Distributed Feedback Dye Laser (DFDL) system for picosecond pulse generation. This system consists of an oscillator-amplifier DFDL, either in the grating or in the prism configuration: both stages are pumped by a single TEA nitrogen laser with improved beam quality. Single pulses having duration of 26 ps are obtained at a frequency up to 100Hz; the overall pulse-to-pulse stability is, at the maximum frequency, of about 25%. This system is particularly well-suited for time-resolved fluorescence microscopy studies where short tunable laser pulses of low energy are required. [ABSTRACT FROM AUTHOR]

In an ocular model plasmas were induced by Q-switched, commercially available Nd:YAG lasers that operated in low order or fundamental mode. Plasma shielding was measured and analysed in relation to energy input, number of plasmas and plasma evolution. Near breakdown threshold, attenuation or shielding of the laser beam resulting from absorption and scattering by the plasma is low and is characterized by high variability from shot to shot. More importantly, shielding does not increase when multiple plasmas are formed, possibly due to a competitive mechanism between these plasmas. Further evidence of this mechanism was obtained from measurement performed using a streak camera. The effectiveness of shielding is scarcely changed by an increase in the cone angle of the incident radiation. In the light of these experiments and other published data, safety guidelines for the clinical use of the Nd:YAG laser have been formulated. [ABSTRACT FROM AUTHOR]

A simple and relatively inexpensive microprocessor-controlled apparatus to measure pulsed spectra has been developed. The system enables the average for a given number of pulses to be taken at each data point. Spectra of a mercury lamp are presented as an example. [ABSTRACT FROM AUTHOR]

The analysis of the spatial and temporal dynamics of plasmas induced in liquids by nanosecond laser pulses, based on a model of moving breakdown combined with a model of distributed shielding, is herein presented. Time- and space-resolved characteristics of energy absorption and transmission are evaluated with the aid of the two models, and compared to experimental findings available in the literature. In particular, energy absorbed per unit length and volume of the plasma column, time-resolved transmission, and energy input-output characteristics of the plasma, are considered. The dependence of the plasma attenuation of the focusing geometry is also discussed. The relevance of this analysis in relation to laser photodisruption is finally outlined. [ABSTRACT FROM AUTHOR]