Measurement of laser diode astigmatism

Theoretical and experimental studies are presented on the two commonly used laser diode astigmatism measurement methods: the moving-diode method and the moving-profiler method. Both methods use lens(es) to focus the laser beam and a camera (or beam profiler) to locate the focal point of the focused beam. It is theoretically shown that the moving-diode method is valid when the distance between the diode and the lens is much larger than the lens focal length and the camera is positioned at a corresponding distance to the lens, and that virtually no calculation is required in a measurement. It is theoretically and experimentally shown that the moving-profiler method is valid when the measured data are elaborately processed using Gaussian optics and that the previous measurement with the measured data being processed by geometric optics was wrong.