Many new 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. A HgCdTe sensor was selected for detecting the laser output and this sensor was interfaced 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 model using a cross-correlation technique in the Fourier domain. This software provided 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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© 1994 Laser Institute of America.
1994
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