Masters Theses

Date of Award

5-1993

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

L. Montgomery Smith

Committee Members

Bruce Bomar, Mary Helen McCay

Abstract

Many new composite materials are difficult or impossible to weld by conventional methods. The quality of the cut or weld in these materials is dependent upon the power of the laser pulses applied to the workpiece, as well as the temporal characteristics of the laser beam. Therefore, it is desirable to monitor and/or control the laser output in real time. This paper presents work towards the design of a laser output monitoring system. This research was begun by selecting a sensor for detecting the laser output and interfacing this sensor to a data acquisition system for further study of the laser output. A model of the ideal laser output was developed based on current knowledge of the laser. Several experiments were conducted to capture temporal laser output data under various conditions. Software was then written to process this data and compare it to the developed theoretical models using a cross-correlation technique in the Fourier domain. The laser model was then refined to represent the actual laser output more accurately. Then, the data processing software was written for real time processing and output of information on laser health as well as temporal and frequency characteristics. Finally, specifications were formulated for the hardware required for a real time system and recommendations were made for further study.

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