JPH01246519A - Dustproofing device for optical parts - Google Patents

Abstract

PURPOSE:To protect optical parts against sticking of dust and dirt contained in the ambient atmosphere by utilizing a cylindrical body having double structures to form a toric outflow port and adjusting the quantity of the dry air to be discharged to a specific value. CONSTITUTION:The dry air is supplied to the gap B formed to a circumferential shape through plural pieces of supply ports 6 circumferentially at equal intervals on the outside cylinder 4 having a cylindrical shape so that this dry air leaks from between the open end part of the inside cylinder and the optical parts to fill the inside of the cylindrical body. The dry air forms the flow heading toward the outside over the entire area of the cylindrical body 5 when the flow rate of the dry air is so adjusted that the Reynolds number attains 200<=Re<=500. The stagnation of very slight fine powder is then merely generated in the central part at the outlet of the inside cylinder 5 and the infiltration thereof into the deep inside part is obviated. Sticking of the dust in the ambient atmosphere to the optical parts is thereby averted and the degradation in output and the deterioration of the optical parts are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a structure for dustproofing optical components used in laser processing equipment.

(Prior Art) Processing devices that utilize high-power lasers such as carbon dioxide lasers have been commonly used. In such processing equipment, if dust used or generated from the workpiece adheres to the optical parts, the absorption rate of laser light will increase, hindering the transmission of laser light and reducing the performance of the processing machine. or reduce the life of optical components. Among optical components, transparent dielectric materials such as the output window of a laser oscillator and a beam splitter are difficult to form a free cooling structure, so if dust adheres to them, a thermal lens effect occurs. Thermal lens effect here refers to a phenomenon in which optical components absorb laser light and generate thermal stress, essentially acting like an optical lens and impairing the transmission characteristics of laser light. .

Therefore, the output window, beam splitter, etc. are housed inside the oscillator case or in a special box.
It may be possible to prevent this phenomenon by making it completely dust-proof, but since these cases and boxes require holes for the laser light to pass through,
A hermetically sealed structure is impossible.

Therefore, conventionally, as a measure to prevent dust and dust from adhering to optical components, a method of flowing dry air around optical components has generally been taken. In this method, as shown in FIG. 7, a cylindrical member 11 is attached to the opposite side of a mount 2 for attaching the optical component 1 to a laser oscillation container (not shown). The cylindrical member 11 has a dry air supply port 12,
Dry air is supplied to the inside of the cylindrical member 11 from a dry air supply source (not shown) via the regulating valve 7 .

(Problem to be Solved by the Invention) However, even in the method of flowing dry air around optical components, it is known from experience that simply blowing dry air cannot completely prevent optical components from adhering to dust and dust. ing. One possible reason for this is that when dry air is simply blown, the dry air entrains surrounding dust and an atmosphere containing dust, as shown in FIG. In order to operate a laser processing machine stably over a long period of time, it is necessary to completely prevent dust and dust from getting into the atmosphere and, ultimately, from adhering to optical components.

Therefore, an object of the present invention is to provide a dustproof device for optical components that can prevent a decrease in output and deterioration of optical components by protecting the optical components from adhesion of dust and dust contained in the surrounding atmosphere. do.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention is characterized in that a gap is formed circumferentially by closing the circumference of one end of a double cylinder so that the cross section forms a U-shape. The cylindrical body is constructed such that the outer cylinder of the double cylinder protrudes beyond the inner cylinder, and the outer cylinder on the open end side of the cylindrical body is attached to one surface of the optical component via a mount. Then, a plurality of dry air supply ports are provided at equal intervals on the outer cylinder of the cylindrical body,
The present invention is characterized by a structure in which dry air is supplied to the circumferential gap through this supply port by a dry air supply device.

(Function) With the above-described configuration, in the present invention, dry air is supplied from the dry air supply device to the circumferentially formed gap through the supply port provided in the outer cylinder of the cylindrical body, and this dry air is supplied to the inner cylinder. It leaks from between the open end of the lens and the optical component and fills the cylindrical body.

Therefore, dust and dirt contained in the surrounding atmosphere will not enter the inner cylinder and adhere to the optical components, making it possible to prevent a decrease in output and deterioration of the optical components.

(Example) A first example of the present invention will be described below with reference to FIG. This figure is a sectional view of the dustproof device attached to the output window. Reference numeral 1 denotes an output window as an optical component, which is attached via a mount 2 to a laser oscillator (not shown). Then, the cylindrical body 3 is attached to the side of the mount 2 opposite to the laser oscillator. The cylindrical body 3 has an outer cylinder 4 fixed to the output window 1, and a large diameter part 5a opposite to the output window 1 inside the outer cylinder 4, which is airtightly held by the outer cylinder 4, and has a predetermined interval between the outer cylinder 4 and the outer cylinder 4. and an inner cylinder 5 forming a circumferential gap A. The inner cylinder 5 has a shorter axial length than the outer cylinder 4, and has a predetermined gap B between it and the output window 1. Further, a plurality of supply ports 6 for clean dry air (dry air) are provided in the outer cylinder 4 at equal intervals in the circumferential direction, and are connected to a dry air supply source (not shown) via a dry air adjustment valve 7.

The operation of the embodiment described above will be explained below.

Dry air supplied from a dry air supply source (not shown) is sent to the gap A through the supply port 6, and from there is sent out almost uniformly from the entire gap B provided in an annular shape, filling the inner cylinder 5 and filling the output window. It flows from side 1 towards the left side of the drawing.

The results of experiments conducted under various conditions in which dry air flows will be described below with reference to FIGS. 2 to 5. In general, the properties of a flow are defined by the Reynolds number (Re), and vary depending on the following relationship expressed by the inner diameter d of the cylinder 5, which is a representative length, the flow velocity U, and the kinematic viscosity coefficient ν.

Re -ud/v The inventors conducted an experiment in which the dustproof device shown in FIG. 1 was immersed in a liquid turbid with fine powder, and fresh water was blown away. This experimental result shows that similar effects can be obtained in gas flows due to the flow similarity law.

FIG. 2 shows the case where Re<200, and the flow inside the inner cylinder 5 is localized because the inflow of fresh water sent into the inner cylinder 5 from the circumferential gap A through the gap B is too small. A flow of the turbid liquid into the inner cylinder 5 occurs, and adhesion of dust to the surface of the output window 1 is unavoidable.

In addition, in the case of Re>500, as shown in FIG. A peripheral flow that flows outward and a central return flow that flows inward are generated, and this central return flow causes the turbid liquid to flow into the cylinder 5 and prevent dust from adhering to the surface of the output window 1. Inevitable.

When 200≦Re≦500, as shown in FIG. 4, the flow is directed to the outside over the entire area of the inner cylinder 5, and only a small amount of fine powder stagnates at the center of the outlet of the inner cylinder 5. Since the flow can be prevented from entering deep inside, the area near the surface of the output window 1 is protected while remaining clean. Therefore, implementation under these conditions is most desirable.

Furthermore, in order to equalize the flow of fresh water into the gap A, it is desirable that the supply ports 6 be arranged at equal intervals in the circumferential direction. For example, when we conducted an experiment with only one supply port 6, we found that no matter what the Reynolds number Re was, there was no range in which the output window 1 could be protected from dust. Even in the range where the flow is localized as shown in Figure 5, the surrounding turbid liquid flows into the inner cylinder 5.
This is clear from the fact that it invades the inside of the computer.

As mentioned above, this experimental result shows that similar effects can be obtained in gas flows due to the flow similarity law. Therefore, as explained above, by forming an annular outflow port using a double-layered cylindrical body and adjusting the amount of dry air discharged from each supply port using the adjustment valve 7 so that the amount of dry air is equalized. The output window 1 can be protected from dust in the surrounding atmosphere. The most desirable condition at this time is that the Reynolds coefficient Re is 200≦Re≦500, and the output window 1 can be almost completely protected.

Next, a second embodiment will be described with reference to FIG. This figure shows the inner tube 5 shown in FIG. 1 of the first embodiment divided into two parts: an inner tube 5a held on the outer tube 4 side and an inner tube 5b on the mount 2 side. Also, the same effects as in the first embodiment described above can be obtained.

In the above-mentioned embodiments, an example in which the present invention was applied to an output window was explained, but the present invention can also be appropriately applied to other similar optical components such as a beam splitter.

[Effects of the Invention] As explained above, according to the present invention, dry air is supplied from the dry air supply device to the circumferentially formed gap through the supply port provided in the outer cylinder of the cylindrical body, and this dry air is Since dry air leaks from between the open end of the inner cylinder and the optical component and the cylinder is filled with dry air, dust from the surrounding atmosphere will not adhere to the optical component.
It becomes possible to prevent a decrease in output and deterioration of optical components.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the first embodiment of the present invention, and FIGS.
The figure is an explanatory diagram of the experimental results according to the first embodiment, Figure 5 is an explanatory diagram of the experimental results when there is one dry air supply port, and the sixth
The figure is a sectional view of the second embodiment of the present invention, FIG. 7 is a sectional view of the conventional example, and FIG. 8 is an explanatory diagram of the operation of the conventional example. 1...Output window, 2...Mount, 3...
・Cylindrical body, 4...Outer cylinder, 5...Inner cylinder, 6...
Supply port, 7...adjustment valve. @1 figure δ 21st! l δ Figure 3 Figure 4

Claims (1)

[Claims] A gap is formed circumferentially by closing the space between the cylinders at one end of the double cylinder so that the cross section forms a U-shape, and the outer cylinder of the double cylinder protrudes more than the inner cylinder. a cylindrical body, and a dry air supply device that provides a plurality of dry air supply ports at equal intervals in the outer tube of the cylindrical body and supplies dry air to the circumferential gap through the supply ports. A dustproof device for an optical component, characterized in that an outer cylinder on the open end side of the cylindrical body is attached to the optical component via a mount.