This thesis is concerned with the application of Laser Microprobe Mass Spectrometry (LAMMS) to the microanalysis of inorganic materials and in particular to the quantification of such analyses. The investigation consists both of an assessment of the capabilities of a LAMMS instrument, the Cambridge Mass Spectrometry LIMA 2A, and an attempt to correlate experimental results with theoretical predictions. The principles of the operation of a LAMMS instrument are discussed and a description of the LIMA 2A instrument is presented. A survey of the literature concerned with the interaction of a high-powered laser with a solid specimen to produce a plasma, the basis of the LAMMS technique, is included. Particular emphasis is given to the description of this interaction in terms of a model based on a local thermodynamic equilibrium (LTE) in the plasma. This model is applied to the conditions estimated to be produced in the LIMA instrument to make simple predictions of expected results. A discussion of the possible methods for converting LAMMS data into a quantitative analysis is given, along with a brief description of the statistical techniques used for data handling. Several model materials, principally chosen for their well-defined composition and known lateral homogeneity, are used in this work. These are single-crystal silicon, a binary copper-nickel alloy and three III-V semiconductors drawn from the Ga-In-As system. The effect of the instrument itself is investigated, with a view to establishing its contribution to the errors observed in the data. This is followed by an investigation of the variation of both the absolute and relative ion signals produced. The variations in the relative ion signals are then compared with the predictions of the LTE model in an attempt to establish its validity. This comparison is also used to estimate the conditions produced in the laser-induced plasma and their variation with specimen chemistry and laser power density. The general conclusions of the investigation are drawn together in a discussion of the preferred methods for the quantification of LAMMS data and the expected error in the resulting analysis. It is shown that, provided appropriate methods are used, the LAMMS technique can provide quantitative analyses with precisions of about 5-20%.

The technique of laser speckle photography has been developed with the aim of measuring the strain field around the tip of a fast crack. An image processing system to allow automatic point-by-point analysis of a speckle photograph is described. The Young's fringes diffraction pattern, produced by directing a narrow laser beam through the photograph, is digitised and processed by computer. Two algorithms have been developed based on Fourier and Walsh spectral analysis. The system can measure speckle displacements with an accuracy of better than 0.1 μm. A new technique for measuring time-varying displacement fields by multiple exposure of a single photograph is presented. Results are shown from a five-exposure speckle photograph of a cantilever deformed under quasi-static conditions. Extension of the technique to dynamic problems requires a stroboscopic laser light source; one chapter deals with the development of a Q-switched ruby laser for this purpose. Modulation of the cavity losses with a Pockels cell at up to 1 MHz results in a train of short (~50 ns) light pulses at the modulation frequency. Results are presented from the analysis of speckle photographs of cracks in polymethylmethacrylate (PMMA) under quasi-static loading. Three different data analysis methods for estimating the stress intensity factor from the displacement field are proposed and evaluated. Preliminary results from dynamic crack propagation studies are described. The dynamic stress intensity factor is estimated from double exposure speckle photographs of fast cracks in PMMA, recorded with the ruby laser in double pulse mode. The application of the techniques of moire and high speed photography to the study of dynamic fracture is also discussed; results are presented from a sequence of moire photographs recorded at 5 x 10<SUP>5</SUP> frames s<SUP>-1</SUP> . Further topics covered in the dissertation include a theoretical analysis of viscoelastic losses as a function of crack velocity, and strain-to-failure measurements on plastic bonded explosives in the Brazilian test using laser speckle photography.

Recent advances in experimental laser cooling have shown the possibility of stopping an atomic beam using the light pressure force of a counter-propagating laser wave. As an application to laser cooling, it is proposed to build a single frequency cesium laser that has a narrow linewidth. Laser cooling techniques are used to cool an atomic beam of cesium to an average velocity of 5 m/s, corresponding to a temperature of 0.2°K. Expressions of the basic forces that a laser wave exerts on atoms are derived according to a semi-classical approach. The experimental problems and methods of avoiding these problems are treated in detail. A computer Monte-Carlo simulation is used to discuss the feasibility of building the proposed laser. This simulation was done for an ensemble of 10,000 atoms of cesium, and it included the effects of the gravitational force and the related experimental variables. The possibility of building single frequency lasers that use a cooled medium of noble gases, and many other applications of laser cooling are briefly discussed at the end of this work.

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