Abstract: An electronic circuit is provided to improve the performance of a conventional power supply for driving a He-Ne laser. In order to avoid an undershoot of the DC current due to operation of the feedback circuit at driving start of the laser, a feedback interrupting circuit is provided in the power supply which compares a detected voltage with a first reference voltage smaller than a predetermined voltage to produce a resultant voltage when the detected voltage is larger than the first reference voltage. The resultant voltage is charged at a charging circuit with a charging time constant to produce a charged voltage. The charged voltage is compared with a second reference voltage having a predetermined voltage level, and the feedback circuit is prevented from producing the control signal during the time interval when the charged voltage is smaller than the second reference voltage.

Abstract: There is prevented mirrors from being misaligned owing to a thermal expansion difference caused by temperature distribution along constituent portions of an argon ion laser supporting the mirrors to improve the stability of a laser output. For this purpose, a member having a thermal expansion coefficient to cancell a thermal expansion difference is joined with any of portions of the cathode bulb supporting the mirrors both constituting an optical resonator, said portions demonstrating a temperature difference.

Abstract: The gas laser tube has a cap-shaped mask attached to the outer surface of an output mirror portion. The mask has an aperture or a window on the bottom thereof to pass a laser beam therethrough. The mask can be rotated around the laser optical axis. The center position of the aperture is located so as to deviate from the rotational center of the mask. Therefore, even when the laser output optical axis is deviated from the rotational center of the mask, the laser beam may easily be adjusted to position within the aperture simply by rotating the mask.

Abstract: An ion laser comprises a main circuit for maintaining the discharge state of an ion laser tube, and an auxiliary circuit for adding an auxiliary DC voltage to a main DC voltage of the main circuit. The impedance of the auxiliary circuit is much larger than that of the main circuit when the ion laser tube has been discharging. At the starting of the ion laser tube discharge, a starter circuit drives the ion laser tube to discharge in accordance with an added voltage of the main and auxiliary DC voltages. Thereafter, the auxiliary circuit is substantially separated from the main circuit due to the difference of the impedances. As a result, surplus power which is not consumed in the ion laser tube is decreased to be negligible.