The generation of the laser beam was understood by the semiclassical theory, and the rate equation was derived from the semiclassical theory. From this process of the laser oscillation, amplification, and mode-locking were understood. And all devices of our system were specified. The mode-locking pulse can not be caught because that the fast oscilloscope was disordered. In conventional mode operation the pulse width is about 2.5 ms, but the spiking pulse can not be seen easily since the impedence mismatches between the photo diode and the oscilloscope input. The calculated pulse width agrees well with the experimental data. Although the perfect operation of our ruby laser system were not by lacking of many parts, we can prepare the future experiments. I believe that these experiences can help the future experiments.