Abstract: A rectangular opening/closing bar is formed, which is inserted in the curl ring of the ring binder to bind papers. The tip end of the opening/closing bar 28A is provided with an instruction portion 28a to raise and open ring pieces in turn while inserting the opening/closing bar 28A. Further, the opening/closing bar may have swollen portions on both ends of the opening/closing bar 28A to enable the bar slide smoothly in the curl ring. And it may be provided with a guide plate 28D perpendicular to the side wall 28b of the opening/closing bar 28A of the swollen portions side. In order to enhance the workability of the opening/closing bar, it may be preferable to use an auxiliary device for positioning the ring binder.

Abstract: A hollow cathode type metal ion laser utilizing negative glow discharge for generating a laser beam. A hollow cathode is inserted into a glass tube, and there are provided springs between opposite ends of the hollow cathode and adjacent ends of the glass tube respectively.

Abstract: A helium-cadmium ion laser is disclosed which has a tubular housing hermetically closed at both ends by Brewster windows and having a hollow cathode mounted therein. Disposed outside the hollow cathode and open to its interior are a row of primary anodes and a row of metal chambers containing a metal material to be vaporized. A pair of secondary anodes are further disposed adjacent the opposite ends of the hollow cathode for protecting the Brewster windows from contamination by the metal vapor by sending it back into the hollow cathode. In order to prevent the metal vapor from depositing on the ends of the hollow cathode on being thus sent back, a pair of tubular insulators are coaxially mounted next to the opposite ends of the hollow cathode for the passage of the metal vapor therethrough. Each tubular insulator has a bore including a smaller diameter portion away from the hollow cathode, and a larger diameter portion closer to the hollow cathode.

Abstract: A He-Cd ion laser of the type having a series of anodes open to the interior of a hollow cathode, a series of metal chambers containing a supply of Cd to be vaporized, and a heater for heating the metal chambers for vaporizing the Cd supply. For holding constant the Cd vapor pressure within the hollow cathode and, in consequence, the intensity of the output beam, an electric control system is provided which comprises a constant current regulator connected to each anode for supplying a constant current thereto, and a heater control circuit for controlling the magnitude of a current fed to the metal chamber heater so as to hold the output voltage of each constant current regulator equal to a reference voltage.