The melting of carbon at a pressure of about 1 atm is observed. The escape of liquid carbon from the heating region and its spread over the sample surface are observed in the experiments. The structural change in graphite occurring in the melting region are determined from scanning tunneling microscope (STM) images obtained by means of an atomic force microscope and from Raman spectra. The STM images exhibit significant rearrange¬ment of the structure of the graphite surface in the region of the escape of liquid carbon. The Raman spectra show that the graphite ordering degree increases significantly. A method for reconstructing the surface relief from the video image is proposed and realized. The method is based on the measurement of the angular distribution of the light intensity scattered by the graphite sample surface. The surface relief of the graphite sample changing in time is reconstructed. The relative change in the relief height during laser excitation is measured. The statistical characteristics of the reconstructed graphite surface shape and their variation during laser irradiation are studied.
Diagnostics of laser-induced instabilities on surface of substance has been carried out by means of fractal geometry and nonlinear dynamics methods. The spatial and temporal characteristics of optical images of melted metal surface were obtained. The obtained characteristics may be used for automatic control by laser technological processes. (Summary only available)
For the diagnostics of processes induced by laser radiation we developed the system on basis of copper laser. This system (laser monitor) consists of laser brightness amplifier, CCD-camera, computer, and allows to obtain the image of a processing surface through plasma plume in a real time. In contradistinction to classical schemes of laser processing our system realizes continuous visual control of processing surface directly in the process of laser radiation interaction with material. The computer analysis of obtained information allows to form control signals for the laser technological complex. The offered system provides the increasing of reliability and accuracy of carrying out measurements and can be used in various technological processes of treatment of metal. In this report we present the result of processing the optical images of dynamic processes on substance surface by fractal geometry methods.
The experimental studying and mathematical modeling of laser-induced hydrodynamic phenomena has been carried out. The mathematical modeling of waves on surface of melted material is realized for case of pressure of return vapor presence. The form of free surface of melted material under the laser radiation action were determined.
The experimental studying of laser-induced hydrodynamic phenomena has been carried out by the system on base of laser brightness amplifier. The surface waves were registered and their parameters were determined. The form of free surface of melted by the laser radiation material was determined. New results of the field to study the laser- induced dynamic processes on the substance surface by the fractal geometry approach are presented.
Provided is the experimental study of the laser melting, treatment and oxidation of metals and alloys (steel, copper, brass, titanium and others) in a real time by the laser brightness amplifier on the basis of a copper laser. The image processing of obtained results has been carried out by computer. Worked out is the technique of measuring of the oxide layer growth by registration of movement of the interference minima (maxima) in reflective ability for radiation of the copper laser reflected from the inhomogeneous distribution of oxide over the cross section of the interaction zone. The results are compared with introduced theoretical models.
Reported is the observation of laser treatment processes of materials by the brightness amplifier based upon the copper laser. Provided is an experimental investigation of melting stainless steel under the laser radiation. Real time monitored is the process of surface heating, melting, spreading a melting boundary and the progress of turbulent movement in the melting container.
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