DE2039442A1 - High-power gas laser - Google Patents

Description

with the electrodes and the voltage source is unnecessary, whereby the efficiency of the system is increased · The effective electrode length "is approximately one meter, the The output beam diameter is approximately 30 mm and the continuous output power is over 1 kW.

Starting point of the invention:

The invention relates to lasers and, more particularly, to a high power (1kW or more) gas transport laser.

For a long time there has been a search for a practically feasible 1 kW continuous radiation laser and for a successful operation of such a laser. Although such high powers can be achieved with lasers in which a gas mixture is used that contains CO "as the laser medium, such lasers being referred to below as COg lasers, laser systems of this type have become impractical for general applications because of their size" ZeBe _{the maximum continuous output power of typical CO 2} lasers that can currently be produced is approximately 50 watts / m active interaction area length, which leads to a length of 20 m for a power of 1kW Heating in the laser interaction area. By heating the gas, a decrease in the occupation reversal is caused, which is mainly based on the fact that the lower energy levels are filled and, if necessary, the lower laser level is blocked.

The present invention generally seeks a working laser that has continuous output power of 1 kW or more per meter of active interaction area can be achieved.

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2039A42

The invention also seeks a high power continuous laser that achieves an output power of 1 kW / m active length.

In particular, it is a gas transport laser with a closed one Achieved cycle that is relatively compact in structure and works with relatively high efficiency,

Summary of the invention:

The output power of a COp laser becomes significant increased by the fact that the gas through the interaction area across the electrodes and thus across the optical Axis is moved so that the gas led out of the interaction chamber is cooled and that the gas in this Interaction chamber is returned on a closed cycle path. The gas is being used on this orbit of a blower with below the Sehall limit lying. speed moves, and by arranging the electrodes in relation to the direction of gas movement, one obtains for each Electrode length unit has essentially the same laser effect ο In addition, the withdrawal of the heated Gas from the interaction area stabilizes the discharge of this arrangement due to the continuous flow, whereby a stabilizing resistor in the electrode circuit becomes unnecessary. This fact contributes to the increased Efficiency of this system. ■

In the following the invention will be described in more detail with reference to one in the Preferred exemplary embodiment shown in the drawing are explained. In the drawing show:

- 4- * "10980871890.

1 shows a schematic representation in which the laser system shown in accordance with the present invention;

2 shows a section through the electrodes along the line 2-2 in Figure 1;

Figure 3 is a generally schematic, partially in section illustrated side view of a device embodying the invention;

FIG. 44 is a top plan view taken along line 4-4 in FIG. 3 the device shown there; and

Figure 5 is a graph of the output power of the system versus input power.

Description of a preferred embodiment

The laser system embodying the invention is shown in Fig. 1 and comprises a hermetically sealed housing 10 which defines a closed, annular gas path in which a laser interaction area 12, a heat exchanger 13 and a fan 14 are in series. According to a preferred embodiment of the invention, the gas mixture consists of carbon dioxide, nitrogen and helium, the gas mixture being enclosed in such a way that it can circulate on the path 11. In the interaction area 12 are mirrors 17 and 18 on opposite sides of the housing walls 10a and 10b and between the walls 10a and 10b and in the vicinity of the mirrors, on the upstream side of the mirrors, straight tubular electrodes 19 and 20 (see Fig. 2) are attached. The electrodes 19 and 20 have parallel axes A ₁ and A ₂ , which lie at a distance from one another in a common plane P, the perpendicular

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arranged right to the direction of gas flow in the circle 11 is. The electrodes are directly through leads 23 connected to a DC voltage source 22, the electrode 19 being the cathode and the electrode 20 being the grounded Anode forms.

According to a preferred embodiment of the invention, the housing 10 is designed in such a way that an essentially linear gas flow can take place over the entire length of the electrodes at a uniform velocity through the interaction area.This structure is shown schematically in Fig. 1, in which the path 11 has a substantially uniform width T in the vicinity of the interaction region 12. It is believed that an electrical Entladungsζone is formed, which is shown in Figure _e 2 schematically at 24, and in the · interaction region 12 in stretched, it is believed that the electrical discharge is stabilized by the gas flow, whereby a series The stabilization resistor switched with the discharge becomes unnecessary. By extending the discharge into the interaction area, an effective coupling of the electrical power can be achieved in order to generate GOo molecules excited by oscillation in this area. The fact that the stabilization resistor can be omitted further increases the efficiency of the device. By arranging the tubular electrodes in the transverse direction to the gas flow, a substantially unimpeded gas mixture flow can take place, so that only a minimal amount of power has to be supplied to the fan in order to maintain the flow. The laser process takes place in the interaction area, whereby the laser output beam 25 is generated.

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2039AA2

A laser system made in accordance with the present invention that has actually been built and tested istι is shown in Pig »3 and 4, in the drawings The same parts are denoted by the same reference numerals. The hermetically sealed housing 10 has a elongated upper chamber 26 having upper and lower walls 27 and 28 which are parallel to each other and perpendicular extending end chambers 30 and 31 connected to the opposite ends of the upper chamber 26 are. A heat exchanger 13 is connected via planes 33 and * 34 to the end chamber 30 and 31, respectively, and it has a Water jacket 35, through which a plurality of elongated tubes 36 arranged at a distance from one another run, through which the circulating gas can be passed. Cooling water is supplied via inlet and outlet lines 37 and 38 passed through the jacket 35 in order to extract heat from the gas in the tubes 36 by convection Centrifugal fan 15 is driven by a motor 39 and this centrifugal fan moves the gas through the system in the direction indicated by the arrows.

fc The electrodes 19 and 20 consist of copper tubes, and they are connected to external water lines 41 and 42, respectively, in order to continuously supply the electrodes with cooling water _o These electrodes are also connected to the voltage lines 23 via suitable fittings 44, and one of the electrodes, preferably the electrode 20 is grounded. Mirrors 17 and 18 can be mounted on the side walls of the housing 10 ", as shown in the drawing, or they can alternatively be supported in or without the housing. The gas is, as shown in Pig Rotated clockwise, and the mirrors are near and on the downstream side of the electrodes

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19 and 20 arranged.

Although the device above as a source or a generator has been described for coherent infrared radiation it can also be used as an amplifier can be used for a coherent beam which is irradiated into the device from an external source in the interaction region. One such application the system is in Pig. 4 in which the system is modified so that an external coherent radiation source or a laser S and optionally additional mirrors 46 and 47 are provided in the vicinity of the mirrors 17 and 18, as shown in the drawing. From the external source S a beam B is introduced through a suitable opening in of the side wall of the housing 10 is radiated into the interaction space 12, with the help of the mirrors 18, 46 and 47 can be reflected several times through this area or where the arrangement can be made so that that the beam only passes once through the alternating area of action and the beam then eventually exits as an amplified beam at 48. Thus, the laser effect the device can be used to achieve a gain if necessary.

A preferred embodiment of one embodying the invention Laser system that has been successfully built and tested has the following physical parameters and typical operating data:

Dimensions:

Height H 122 cm

Length L 152 cm

Width W 102 cm

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Depth of the interaction area 7 cm

(typical) gas parameters

Mixture of CO ₂ , He, Ϊ

Pressure (torr) CO ₂

Hey

N ₂

Maximum gas temperature

Flow velocity at the electrodes Electrodes

Material diameter

Cathode anode

Distance between electrodes Active length

(typical) output beam Diameter wavelength mode purity

power

Efficiency tube
all in all

A graphical representation of the actual test results with the system described above is shown in FIG.

2 cm 5 cm 11 cm 40O ⁰ K m mm around , unpola- ized clearing 30 m / sec. watt Copper tubes 0.93 0.63 5.08 1 30th 10.6 Multiple mode 1000 10 ok 8 4

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Claims (1)

Pat en tan s slogans High-power gas laser ge ken marked by a hermetically sealed housing (10), which has an elongated fluid path, which is formed in Έ _ο χμ a closed loop, and contains a gas mixture, through a device (14) »around the gas mixture in one direction to move this path, by at least two spaced apart, elongated electrodes (19 »20) which are held by the housing and in the housing and run transversely to the direction of flow of the gas flow, the electrodes having active parts with which an electrical Discharge across this Pluidbahn can be generated by an electrical voltage source (22), which is connected to the electrodes, through a laser oscillator cavity (12) with at least two mirrors (17, 18) attached to this housing near the electrodes and located on the downstream side of these electrodes optically aligned with one another along the optical axis of the system are estigt, this optical axis running transversely to the gas flow direction, and by a device (13) ι to cool the gas mixture. 2 · A device according to claim 1, characterized geke η η - ζ calibration η β t in that the gas mixture contains carbon dioxide. 3. Device according to claim 2, characterized in that g e k e η η that the mixture also contains helium and nitrogen » 4. Device according to one of claims 1 to 3 »thereby geke η η ζ β ic h. η et that the active parts of the electrodes (i9 _f 20) run straight and parallel to each other 10 9808/1890 and that the axes (A ^, A ₂ ) are arranged in a common plane which is perpendicular to the direction of flow, 5. Device according to one of claims 1 "to 4, characterized characterized in that the electrodes (19, 20) are tubular, and that means (41 »42) are provided in order to conduct a fluid through these electrodes in order to cool the electrodes. 6ο device according to one of claims 1 to 5 »thereby characterized in that the housing has two plane-parallel walls (10a, 10b) in the vicinity of the electrodes, which are arranged at a distance (T) from one another which is greater than the effective length of the electrodes (19, 20), and which form a substantially unobstructed fluid path. 7ο Device according to one of claims 1 to 6, characterized geke nnzeich that an external radiation source (S) is provided for a coherent radiation, the has a jet (B) which is directed into the cavity in such a way that it is at least once transverse to the direction of gas flow runs, increasing the energy of this beam. 109808/1830