HIGH-FREQUENCY DISCHARGE-EXCITED LASER UNIT

Abstract: A high frequency voltage is applied to the electrodes (6a,6b) of a laser tube (5) whilst a laser medium gas is circulated through the laser tube. A high-frequency inverter (2) and a matching circuit (3) are located close to the optical resonator unit (7) and are directly coupled to the laser tube (5). A DC supply (1) provides direct power to the high-frequency inverter (22) through ordinary cables.

Description: The present invention relates to a high-frequency discharge-exciting laser device having a laser oscillator including a laser tube in which a laser medium gas is circulated, and more particularly to a high-frequency discharge-exciting laser device in which a high-frequency inverter, is coupled to the optical resonator. High-frequency discharge-exciting laser devices are employed for increasing the efficiency of laser output. One example of such a high-frequency discharge-exciting laser device is illustrated in FIG. 5 of the accompanying drawings. Designated in FIG. 5 at 1 is a DC power supply including a regulator circuit for rectifying a three-phase AC input into a DC output and keeping the DC voltage at a constant level as required. A high-frequency inverter 2 converts the DC input into a high-frequency AC output having a frequency ranging from 1 to several MHz. A matching circuit 3 of π-type serves to provide impedance matching between the output of the high-frequency inverter 2 and a coaxial cable (described later). The coaxial cable, denoted at 4, transmits high-frequency electric power from the high-frequency inverter 2. A laser tube 5 has electrodes 6a, 6b respectively on its opposite sides, and a laser medium gas is circulated in the laser tube 5. By applying high-frequency electric power to the electrodes 6a, 6b, an electric discharge is excited to oscillate and amplify a laser beam in the axial direction. The matching circuit 3 and the laser tube 5 are placed at a considerable distance from the high frequency inverter 2 and the like. The coaxial cable has an impedance which is normally of 50Ω. Therefore, the coaxial cable is poor in its matching capability with the high-frequency inverter and the laser tube, and a matching arrangement such as for automatic tracking is complex and expensive. The coaxial cable causes a large high-frequency loss. Moreover, coaxial cables which can transmit high electric power are limited and expensive. The coaxial cable limits the distance by which a laser head can be spaced from a cabinet that houses the high-frequency inverter. In addition, the coaxial cable has to be shielded at its opposite ends for protection against radio disturbance. It is an object of the present invention to dispense with the coaxial cable, etc., and hence provide a laser device which is well controllable and highly reliable. There is provided therefore in accordance with the present invention a high-frequency discharge-exciting laser device having a laser oscillator including a laser tube in which a laser medium gas is circulated, comprising: a DC power supply for rectifying an AC input and issuing a DC voltage; a high-frequency inverter for supplying high frequency electric power to said laser tube; a matching circuit for gaining impedance matching between said high-frequency inverter and said laser tube; and said high-frequency inverter and said matching circuit being disposed on the surface of said optical resonator. Since the high-frequency inverter and the matching circuit are disposed in the same position as that of the optical resonator, no coaxial cable is required, it is not necessary to take impedance matching with any coaxial cable into consideration, and the matching cable is simple and inexpensive. Preferably, also, the DC power supply is also disposed immediately adjacent to the optical resonator. Two examples of devices according to the present invention, will now be described with reference to the accompanying drawings, in which:- FIG. 1 is a circuit diagram of a first embodiment of the present invention; FIG. 2 is a perspective view of the embodiment of the present invention; FIG. 3 is a circuit diagram of another embodiment of the present invention; FIG. 4 is a perspective view of the other embodiment of the present invention; and FIG. 5 is a circuit diagram of a high-frequency discharge-exciting laser device which employs a coaxial cable. An embodiment of the present invention will hereinafter be described in specific detail with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment according to the present invention. Those elements in FIG. 1 which are identical to those shown in FIG. 5 are denoted by identical reference numerals. Designated at 1 is a DC power supply including a regulator circuit for rectifying a three-phase AC input into a DC output and keeping the DC voltage at a constant level as required. A high-frequency inverter 2 converts the DC input into a high-frequency AC output having a frequency ranging from 1 to several MHz. A matching circuit 3 of π-type serves to gain impedance matching between the output of the high-frequency inverter 2 and a laser tube (described later). The laser tube, denoted at 5, has electrodes 6a, 6b, an respectively on its opposite sides, and a laser medium gas is circulated in the laser tube 5. By applying high-frequency electric power to the electrodes 6a, 6b, an electric discharge is excited to oscillate and amplify a laser beam in the axial direction. The high frequency inverter 2 and the matching circuit 3 are disposed in the same place as that of the laser tube 5, so that the distance between the matching circuit 3 and the laser tube 5 is small and no coaxial cable is required therebetween. Impedance matching only needs to be considered between the high-frequency inverter 2 and the laser tube 5, and hence the matching circuit 3 can easily be designed for its arrangement. Any shield for protection against radio disturbance is simple as the matching circuit 3 and the laser tube 5 may be shielded together. FIG. 2 shows in perspective the high-frequency discharge-exciting laser device of FIG. 1. The high-frequency inverter 2 and the matching circuit 3 are mounted on an upper surface of the optical resonator 7 including the laser tube 5. As shown, the distance between the matching circuit 3 and the optical resonator 7 is very small, and no coaxial cable needs to be used. The high-frequency inverter 2 and the matching circuit 3 are of a proportionate size as compared with the laser resonator, as shown in FIG. 2. Denoted at 8 is a laser beam output. By installing the device on the head of a laser machining system or the tip end of a robot arm, there is constructed a high-frequency discharge-exciting laser device. As described above, by positioning the high-frequency inverter and the matching circuit near the optical resonator, any coaxial cable is dispensed with, and as a consequence impedance matching can easily be gained, and any shield to safeguard the components against radio disturbance is simplified. Another embodiment of the present invention will hereinafter be described with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment according to the present invention. Those elements in FIG. 2 which are identical to those shown in FIG. 5 are denoted by identical reference numerals. Designated at 1 is a DC power supply including a regulator circuit for rectifying a three-phase AC input into a DC output and keeping the DC voltage at a constant level as required. A high-frequency inverter 2 converts the DC input into a high-frequency AC output having a frequency ranging from 1 to several MHz. A matching circuit 3 of the π-type serves to gain impedance matching between the output of the high-frequency inverter 2 and a laser tube (described later). The laser tube, denoted at 5, has electrodes 6a, 6b respectively at its opposite ends, and a laser medium gas is circulated in the laser tube 5. By applying high-frequency electric power to the electrodes 6a, 6b, an electric discharge is excited to oscillate and amplify a laser beam in the axial direction. The DC power supply, the high-frequency inverter 2, and the matching circuit 3 are disposed in the same place as that of the laser tube 5, so that the distance between the matching circuit 3 and the laser tube 5 is small and no coaxial cable is required therebetween. Impedance matching only needs to be considered between the high-frequency inverter 2 and the laser tube 5, and hence the matching circuit 3 can easily be designed for its arrangement. Any shield for protection against radio disturbance is simple as the matching circuit 3 and the laser tube 5 may be shielded together. FIG. 4 shows in perspective the high-frequency discharge-exciting laser device of FIG. 2. The DC power supply 1, the high-frequency inverter 2, and the matching circuit 3 are mounted on an upper surface of the optical resonator 7 including the laser tube 5. As shown, the distance between the matching circuit 3 and the optical resonator 7 is very small, and no coaxial cable needs to be used. The high-frequency inverter 2 and the matching circuit 3 are of a proportionate size comparable to the laser resonator, as shown in FIG. 4. Denoted at 8 is a laser beam output. By installing the device on the head of a laser machining system or the tip end of a robot arm, there is constructed a high-frequency discharge-exciting laser device. As described above, by positioning the DC power supply, the high-frequency inverter, and the matching circuit near the optical resonator, any coaxial cable is dispensed with, and as a consequence impedance matching can easily be gained, and any shield to safeguard the components against radio disturbance is simplified.

Claims: A high-frequency discharge-exciting laser device having an optical resonator (7) with a laser tube (5) in which a laser medium gas is circulated; a DC power supply (1) for rectifying an AC input and providing a DC output voltage; a high-frequency inverter (2) for supplying high frequency electric power to said laser tube; and an impedance matching circuit (3) between the high-frequency (2) inverter and the laser tube (5); characterised in that the high-frequency inverter and the matching circuit are disposed on the surface of the optical resonator. A device according to claim 1, wherein the high-frequency inverter (2) and the impedance matching circuit (3) are disposed on an upper surface of the optical resonator (7). A device according to claim 1, wherein the high-frequency inverter (2) and the impedance matching circuit (3) are smaller than the optical resonator (7). A device according to any of claims 1 to 3, wherein the DC power supply (1), is also disposed on the surface of the optical resonator (7).

Inventors: EGAWA, A.FANUC MANSION HARIMOMI 3-303
Applicants: FANUC LTD.
Application year: 1987
Main classification: H01S3
IPC codes: H01S3