Abstract: A method of evaluating quality of a laser beam output of an X-Y-Z movement laser processing head of beam generator by detecting an instantaneous profile of the beam by means of dynamical laser beam analyzer, calculating values of beam stability parameter of the beam profiles, each value of the beam stability parameter corresponding to one of the laser beam profiles, comparing the beam profiles detected and adjusting mirror orientation in the generator and calculating a standard deviation of the stability parameters and adjusting condition in supplying a laser gas to the generator.

Abstract: An optical system for a folded cavity laser has a partially transmitting output mirror and a fully reflective folding mirror on one side of an active laser medium, and another folding mirror on the other side of the active laser medium disposed so that a resonating laser beam inside the resonator cavity may make multiple passes to obtain a long effective cavity length. Means are provided for adjusting at least one of the folding mirrors so that the laser beam resonates within the cavity. Means are also provided for adjusting the output mirror so that misalignments of the folding mirrors are compensated.

Abstract: In order to facilitate the initiation of plasma discharge inside a gaseous discharge tube, some form of pre-ionizing the gas is required. This invention describes a technique whereby a small but intense discharge region is created near the cathode of a d.c. discharge in order to generate the necessary electrons to initiate the formation of the main electrical discharge. It makes use of the high negative voltage that is applied on the discharge cathode with respect to the discharge anode. A third auxiliary pin electrode near the cathode is introduced into the discharge tube. It is connected on the outside to the anode through a resistor of a suitable value. In the presence of a high voltage across the main electrodes, corona discharge occurs near the auxiliary electrode. This leads to the formation of a small region of intense discharge between it and the cathode. The electron generated in this small discharge region would drift towards the anode under the high electric field between the main electrodes.