GB2144262A - Igniting a gas laser - Google Patents

Abstract

In an arrangement for firing a gas laser, a piezoelectric means 5 is provided in parallel with a d.c. power source 10 (which is connected to laser anode 2 through a resistor 4) and a laser tube (1) for producing a break-through voltage when mechanical force is exerted upon said piezoelectric means. Feed back of the break-through voltage to the d.c. power source is prevented by a high voltage blocking diode 6, or, in an alternative embodiment, by feeding the voltage pulse through an auxiliary anode. <IMAGE>

Description

SPECIFICATION Method and device for igniting a gas laser The invention relates to a method and device for igniting a gas laser.

Hitherto, the ignition voltages required for initiating the operation of commercially available gas lasers are produced by high voltage ignition cas cadets. The voltages required are considerable, for example, 5 to 1 Skvolt for He-Ne lasers, depending on the type used.

For reasons, of safety, the entire ignition cascade has to be sealed in epoxide resin or silicone gum and is installed in the power supply unit so that the mains f-or the laser head have to be laid out for a higher voltage than the continuous operation voltage. Access to the ignition cascade unit involves the destruction of the seal. Furthermore, U.S.A. Patent No. 3909745 discloses a laser transmitter system which uses mechanical energy for generating a laser output signal in a semiconductor laser. This system as disclosed is not applicable for gas lasers apart from the fact that a capacitor system has to be employed to produce laser pulses.

It is an object of the present invention to obviate the above disadvantages.

It is a further object of the present invention to provide a simple, cheap and sturdy means for firing gas lasers.

In accordance with one aspect of the present invention, there is provided apparatus for firing a laser tube wherein piezoelectrical energy is coupled parallel to the laser tube via an anode resistor, and wherein a high voltage blocking diode is provided in the anode current path.

In accordance with another aspect of the present invention there is provided gas laser apparatus comprising a laser tube filled with a gaseous material and having an anode and a cathode, said anode and said cathode being provided at opposite end portions of said laser tube, a d.c. power source adapted for continuous operation of the apparatus, an anode resistor, a high voltage diode, said anode being electrically connected to the positive terminal of the power source via said high voltage diode and said anode resistor, an electrical connection between said cathode and the negative terminal of the power source, a piezoelectric means coupled to said anode via said anode resistor and coupled to said cathode via said electrical connection, and means for exerting a mechanical force on said piezoelectric means for producing a high voltage pulse at said piezoelectric means, said high voltage diode blocking said pulse towards said positive terminal, and transmitting current from said power source to said anode via said anode resistor, whereby said high voltage pulse ignites said gaseous material in said tube.

By exerting a mechanical force upon the piezoelectric means, the latter produces a break-through voltage which is applied to the laser electrodes for starting operation of the gas laser. The breakthrough voltage is applied via the anode resistor, which is necessary due to electrical capacity of the piezoelectric means.

In accordance with another aspect of the present invention there is provided an apparatus for firing a laser tube wherein piezoelectrically produced energy is fed in parallel between an auxiliary anode and the cathode of the laser tube.

In accordance a still further aspect of the present invention there is provided gas laser apparatus comprising a laser tube filled with a gaseous material and having an anode, a cathode, and an auxiliary anode, said anode and said cathode being provided at opposite end portions of said laser tube and said auxiliary anode being inserted into the laser tube ajdacent said anode, an anode resistor, a piezoelectric means, a power source, said anode being connected to said power source via said anode resistor, said auxiliary anode being connected to said piezoelectric means and said cathode being connected to said piezoelectric means and to said power source, and means for exerting a mechanical force upon said piezoelectric means for producing a high voltage pulse for igniting said gaseous material.

The invention includes the firing of laser tubes by means of piezoelectric energy.

A high voltage blocking diode prevents that the current resulting from the high voltage produced in the piezoelectric means flows through a voltage source provided for the continuous operation of the gas laser, however, is in forward direction for the current flow from the voltage source for feeding the gas laser operation after firing. Alternatively, the blocking diode is omitted and an auxiliary anode is provided in the laser tube.

The invention will now be described further hereinafter, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a laser tube arrangement including a piezoelectric means for producing a break-through voltage; and Figure 2 shows a laser tube arrangement including an auxiliary anode circuit in series with a piezoelectric means.

In Figure 1 a firing circuit comprises a piezoelectric means 5 which has a first terminal connected to one side of an anode resistor 4. The other side of anode resistor 4 is connected to an anode 2 of a laser tube 1. A cathode 3 of the laser tube 1 is connected to a second terminal of the piezoelectric means 5. The laser tube 1 is filled with a gas, for example, He-Ne gas.

The laser tube 1 is only schematically shown, the laser resonator reflectors being omitted for the sake of simplicity.

A d.c. power source 10 has its positive terminal connected to the anode of a high voltage diode 6 whose cathode is connected to the first terminal of the piezoelectric means 5, the second terminal of which is connected directly to the negative terminal of the power source 10.

In operation, a mechanical force F is exerted on the piezoelectric means 5 which produces a high voltage of about 10 kV which is applied across the anode resistor 4 and the laser resonator 1. The resistor 4 of approximately 60 kQ sets the operating point of the laser 1 and further eliminates the capacitive effects inherent in the piezoelectric means 5, the connection lines and the laser 1 itself. A current flows through the anode resistor 4 and excites an induced emission in the lasertube 1.

The diode 6 prevents a current flow through the power source 10 at the moment of generation of the high voltage pulse in the piezoelectric means 5, the diodes 6 at that time being reverse biased. After ignition, a continuous laser discharge takes place due to the current flow from the power source 10 through the now forward biased diode 6.

In the embodiment shown in Figure 1 the same numerals refer to the same components. The anode 2 of the gas laser 1 is connected via the anode resistor 4 to the positive terminal of the power source 10 and the cathode 3 is connected directly to the negative terminal thereof. In contrast to Figure 1 an auxiliary anode 7 is provided which projects into the laser cavity adjacent the anode 2. The auxiliary anode 7 is connected via the piezoelectric means 5 to the power source 10 via the connection between the negative terminal of the powersource 10 and the cathode of the laser 1.

The operation of the embodiment of Figure 2 is similar to that of Figure 1. A force F is exerted on the piezoelectric means 5 which produces a high voltage of about 1OKv which is applied across auxiliary anode 7 and cathode 3 in order to excite an inducted emission in the laser 1. Auxiliary anode 7 obviates the need for the protection diode 6 of Figure 1.

After ignition, a continuous laser discharge takes place due to a current flow from the power source 10.

The solution according to the invention is very simple and easy to manufacture, ensuring a high degree of reliability.

Claims (7)

1. Apparatus for firing a lasertubewherein piezoelectrical energy is coupled parallel to the laser tube via an anode resistor, and wherein a high voltage blocking diode is provided in the anode current path.

2. Gas laser apparatus comprising a laser tube filled with a gaseous material and having an anode and a cathode, said anode and said cathode being provided at opposite end portions of said laser tube, a d.c. power source adapted for continuous operation of the apparatus, an anode resistor, a high voltage diode, said anode being electrically con nected to the positive terminal of the power source via said high voltage diode and said anode resistor, an electrical connection between said cathode and the negative terminal of the power source, a piezoelectric means coupled to said anode via said anode resistor and coupled to said cathode via said electrical connection, and means for exerting a mechanical force on said piezoelectric means for producing a high voltage pulse of said piezoelectric means, said high voltage diode blocking said pulse towards said positive terminal, and transmitting current from said power source to said anode via said anode resistor, whereby said high voltage pulse ignites said gaseous material in said tube.

3. Apparatus for firing a laser tube wherein piezoelectrically produced energy is fed in parallel between an auxiliary anode and the cathode of the laser tube.

4. Gas laser apparatus comprising a laser tube filled with a gaseous material and having an anode, a cathode and an auxiliary anode, said anode and said cathode being provided at opposite end portions of said laser tube and said auxiliary anode being inserted into the lasertube adjacent said anode, an anode resistor, a piezoelectric means, a power source, said anode being connected to said power source via said anode resistor, said auxiliary anode being connected to said piezoelectric means and said cathode being connected to said piezoelectric means and to said power source, and means for exerting a mechanical force upon said piezoelectric means, for producing a high voltage pulse for igniting said gaseous material.

5. The firing of laser tubes, by means of piezoelectrical energy.

6. Gas laser apparatus constructed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.

7. Methods of firing laser tubes substantially as herein described with reference to the accompanying drawings.