JPS5838950B2 - Laterally excited gas laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laterally excited gas laser device,
The purpose is to stabilize the discharge and lower the pressure loss in the laser gas transport path.

To explain a conventional gas laser device of this type with reference to FIG. 1, reference numeral 1 denotes a transport path duct forming a transport path for laser gas 2;
Reference numeral 3 denotes a metal anode plate supported on one side of the transport path duct 1, and 4a and 4b are cathode groups, for example, needle-shaped, which are disposed upstream and downstream of the laser gas 2 flow, facing the metal anode plate 3. The cathode groups 4a, 4b form discharge groups 5a, 5b between them and the metal anode plate 3, and the cathode groups 4a, 4
The arrangement direction b is parallel to the laser optical axis 6 which is orthogonal to the laser gas 2 flow.

7 is a glass plate holding the row-shaped cathode groups 4a and 4b;
A block resistor 8 for stabilizing discharge made of mica, carbon, metal, etc. has a cooling water passage 9 and a block resistor 7
These metal blocks are supported by the transport path duct 1.

Reference numeral 10 denotes a power source that applies voltage between the metal anode plate 3 and the cathode groups 4a and 4b.

In this conventional device, electric energy is injected between the anode metal plate 3 and the cathode groups 4a and 4b by a power source 10, and
2. CO, N2. The laser gas 2 consisting of a mixture of He 2 is excited in the discharge groups 5a and 5b, or the gain (
In order to increase the excitation efficiency (pumping efficiency), it is necessary to lower the temperature of the laser gas 2, so the laser gas 2 is forced to circulate, passes through a high gain area, and the axis perpendicular to the laser gas 2 flow is aligned with the laser optical axis 6. A resonator (not shown) is installed so that the laser beam is extracted from the laser gas excitation space.

However, in this conventional gas laser device, a plurality of cathode groups 4a and 4b are arranged in series in the direction in which the laser gas 2 flows in a single laser gas transport path duct 1. The gas ionized by the glow discharge between the cathode group 4a and the anode metal plate 3 in the downstream cathode group 4b
- It flows into the discharge group 5b constituted by the anode metal plate 3.

In this case, in a culm where the distance between the upstream discharge group 5a and the downstream discharge group 5b is short, the discharge in the downstream discharge group 5b is influenced by the upstream discharge group 5a and is injected into the downstream discharge group 5b. The electrical energy is considerably larger than that of the upstream discharge group 5a, which has the disadvantage of making the discharge unstable.

On the other hand, when considering the fluid pressure loss within the transport path duct 1, the required laser gas flow velocity V in the discharge group is given by the following equation.

However, n3 is the number of rows of discharge groups arranged in series with respect to the laser gas flow, Pl is the discharge input per discharge group-row, C
is the specific heat of the laser gas, p is the density of the laser gas, S is the cross-sectional area of the discharge group space, and (JTmax) is the allowable temperature rise of the laser gas.

In order to keep (l Tmax ) constant, the flow velocity V must be increased in proportion to n.

Fluid pressure loss PS in the laser gas transport path duct
is, P5=αβ■2 ・・・・・・・・・・・・
...■.

Here, α is a coefficient depending on the shape of the transport path duct, β is a coefficient depending on the fluid characteristics of the laser gas, and ■ is the flow velocity of the laser gas given by the above equation (4).

(4) From @formula, fluid pressure loss P is, is given by

However, γ=αβp12/(CpS, 71ITmax
)2.

This shows that when the discharge groups are arranged in series with respect to the laser gas flow, the fluid pressure loss P increases in proportion to the square of the number of rows ns of the discharge groups, and therefore, in the conventional device, the pressure loss can be kept low. That is impossible.

In view of the problems of the conventional device described above, the present invention proposes a gas laser device that can stabilize discharge and reduce fluid pressure loss, by arranging a diversion duct in the laser gas transport path duct, The present invention is characterized in that a branch transport path is formed through which laser gas flows that do not interfere with each other is formed, and discharge groups are arranged in each of the branch transport paths.

To explain the embodiment shown in FIG.
A.

A diversion duct 12 forming a flowchart 11B is provided.

Both ducts IA, 12 are intercepted from heat-resistant insulation.

An anode metal plate 3 is supported on the inner wall of the upper and lower transport path ducts, and cathode groups 40, for example, needle-shaped, are provided in rows, facing the metal anode plates 3, on the upper and lower sides of the branch duct 12, respectively. A discharge group 50 is formed.

Reference numeral 7 denotes a block resistor similar to that of the reciprocating device shown in FIG.

Note that 6 is a laser optical axis, and 10 is a power source.

In this device, as in the conventional device shown in Fig. 1, the laser gas 2
This is forced to circulate in order to lower the temperature of the
A resonator (not shown) is installed to excite the laser gas 2 in the parallel discharge group 4C, and extract laser light from the laser gas excitation space.

From the viewpoint of stabilizing the discharge and reducing fluid pressure loss, since the row-shaped discharge groups 5C are arranged in parallel in the divided laser gas flow that does not interfere with each other, the negative discharge groups 5C are It is not affected by gas ionization due to the electrical discharge in the discharge group 5C, and therefore, stabilization of the discharge can be obtained.

Since the required flow velocity of the laser gas in the discharge section is given by equation (4), the flow velocity when n discharge groups are arranged in parallel with respect to the laser gas flow is equal to the flow velocity when n discharge groups are arranged in series. The flow rate may be 1/n of the current flow rate.

In addition, since the fluid pressure loss in the laser gas transport path when the shapes of the laser gas transport paths in the discharge section are the same is given by the formula 0, the fluid pressure loss when n discharge groups are arranged in parallel is The change in the cross-sectional shape of the laser gas transport path when the discharge groups are arranged in parallel can be smaller than when the discharge groups are arranged in series. Therefore, fluid pressure loss can be reduced.

In the above embodiment, an example was shown in which the cathode group 4C was provided in the diversion duct 12 and the anode metal plate 3 was provided in the transport duct 1-IA, but this relationship may be reversed, and parallel discharge groups 5
Of course, C can be provided in two or more rows.

As described above, in the horizontally excited gas laser device according to the present invention, discharge groups are provided in parallel discharge groups by providing each discharge group in the divided transport path in which the laser gas flow is divided, so that the discharge is stable and This has the effect of lowering fluid pressure loss.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of the vicinity of the discharge section of a conventional horizontally excited gas laser device, and FIG. 2 is a schematic perspective view showing an embodiment of the horizontally excited gas laser device according to the present invention. 1A: Transport path duct, 2elm-2i body, 3: Anode metal plate, 4C: Cathode group, 5C: Discharge group, 12: Diversion duct, 11A, 11B: Diversion transport path.

Claims (1)

[Scope of Claims] 1. A diversion duct is disposed within the laser gas transportation path to form a diversion transportation path, and within this diversion transportation path, there are anodes located on both sides of the laser optical axis and opposing anodes. 1. A laterally excited gas laser device, characterized in that each discharge group is provided with a row of cathode groups. 2. The horizontally excited gas laser device according to claim 1, wherein cathode groups are provided above and below the flow dividing duct, respectively. 3. The horizontally excited gas laser device according to claim 1 or 2, wherein a metal block having a cooling water transport path is disposed in the branch duct.