JP3500752B2 - Laser light attenuator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an attenuator used in a laser processing machine or the like for stably attenuating laser light output from a laser oscillator.

[0002]

2. Description of the Related Art For example, in a laser processing machine that outputs a high power YAG laser of the super 400 W class, it is necessary to perform processing under various conditions. There is.

In such a case, the discharge current and voltage of the laser oscillator are adjusted to lower the output of the laser oscillator,
Although low power laser light is used, when the discharge current of the laser oscillator is lowered to lower the output, the laser output becomes unstable and there is a problem that precise fine processing cannot be performed.

For this reason, in the prior art, the output of the laser oscillator is set to a high output so that a stable output can be obtained, and an attenuation filter is arranged in the optical path of the laser light output from the laser oscillator to attenuate the laser light. There was a method of transmitting the light to the target and attenuating it to the target output.

However, when high-power laser light is attenuated by passing through an attenuation filter having a relatively large attenuation factor, the attenuation filter itself is heated to a high temperature, and the filter is damaged in a short time.

On the other hand, a technique of using a wire screen as an attenuation filter and attenuating a laser beam by diffracting or reflecting the laser beam has been proposed by USP 4,561,721 and the like. There is a problem that the temperature of the housing rises remarkably, resulting in damage to equipment and shortening of life.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to prevent the attenuation filter from being damaged.
It is an object of the present invention to provide a laser light attenuator capable of efficiently attenuating a high output laser light and stably obtaining a low output laser light from a high output laser oscillator.

[0008]

In order to achieve the above object, a laser light attenuating device of the present invention has an attenuating filter arranged in the optical path of a laser light output from a laser oscillator, and the laser light is attenuating filter. In a device for attenuating a laser beam that transmits and attenuates the laser light, water cooling chambers that directly contact and cool the cooling water are provided in front of and behind the attenuating filter, and a plurality of attenuating filters are placed at intervals.
Are installed side by side on the optical path, and a water cooling chamber is provided between the attenuation filters.
Characterized in that it has been.

[0009] Here, the water cooling chamber may be communicatively connected to the cooling water circulation passage for circulating cooling water. further,
A tank may be provided in a part of the cooling water circulation path, and a cooling unit for cooling the cooling water in the tank may be provided.

[0010]

In the attenuator having such a structure, the laser light emitted from the laser oscillator is used so as to pass through the attenuating filter and attenuate the light intensity of the laser light. Since the front surface and the back surface are directly contacted with the cooling water to be cooled, temperature rise is effectively suppressed, damage to the attenuation filter due to heating is prevented, and the life of the attenuation filter can be extended.

Further, when a plurality of filters are arranged in parallel and used, the laser light can be attenuated in stages, and the attenuation amount of the laser light can be reduced in each attenuation filter, so that the laser light can be emitted at a relatively large attenuation rate. Even when attenuating light, it is possible to prevent a rapid temperature rise and prevent damage to the attenuation filter.

Further, since the cooling water in the tank is pressurized and circulated by the pump, fresh cooling water always circulates in the water cooling chamber, which improves the cooling effect of the attenuation filter.

Furthermore, when a plurality of attenuation filters are arranged side by side in a cylindrical casing with a space, the casing is divided into a plurality of casing pieces so that each of the plurality of casing pieces holds the attenuation filter. With the structure to be assembled into, the number of attenuation filters can be freely changed, the transmittance of the attenuation filters can be freely changed, and the attenuation amount can be arbitrarily and easily set with one attenuation device. You can

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a laser light attenuator. The damping device is composed of a water-cooled filter device, a tank for cooling water, and a cooling water supply passage for supplying cooling water. Reference numeral 1 denotes a casing of the filter device, which is formed in a cylindrical shape with both ends open. Five circumferential grooves are formed at intervals in the casing 1, and two transparent glasses 3a and 3b are fitted so as to fit into the circumferential grooves.
And the three attenuation filters 2a, 2b, 2c are the casing 1
It is fitted inside.

As the attenuation filters 2a, 2b, 2c, an ND filter (neutral density filter) is used which obtains an appropriate amount of light by weakening the light intensity at a constant rate regardless of the wavelength. As the ND filter, for example, chromel is used. It is possible to use a metal vapor deposition filter, or a gray filter containing Co and Ni.

The three attenuation filters 2a, 2b, 2c are arranged in the central portion of the casing 1, and the transparent glasses 3a and 3b are arranged outside (both sides) of these attenuation filters.
The three attenuation filters 2a, 2b, 2c are, for example, 1/2
In order to realize the attenuation rate of 0, it is configured and arranged so as to have transmittances of 50%, 50%, and 20% from the laser light incident side, respectively. In this way, by attenuating the laser light stepwise by the plurality of attenuation filters and disposing the attenuation filter 2c having a low transmittance on the emission side, a rapid temperature rise of the filter is prevented and its damage is prevented. be able to.

On the other hand, these transparent glasses 3a, 3b and the attenuation filters 2a, 2b, 2c form four water cooling chambers 4a, 4b, 4c, 4d in the casing 1 for circulating cooling water. Supplied.

That is, the transparent glass 3a and the attenuation filter 2a
A water cooling chamber 4a is formed between them, a water cooling chamber 4b is formed between the attenuation filter 2a and the attenuation filter 2b, a water cooling chamber 4c is formed between the attenuation filter 2b and the attenuation filter 2c, and the transparent glass 3b and the attenuation filter are formed. Water cooling room 4 between 2c
d is formed. The joint between each transparent glass, each attenuation filter and the casing 1 is completely sealed.

The water cooling chambers 4a and 4b are the casing 1
The water cooling chambers 4b and 4c communicate with each other by a water passage 7a provided inside.
Are communicated with each other by the water passage 7b provided in the casing 1, and the water cooling chambers 4c and 4d are communicated with each other by the water passage 7c provided in the casing 1. Further, the casing 1 is connected with an inlet pipe 6a for cooling water and an outlet pipe 6b, the inlet pipe 6a communicates with the water cooling chamber 4a, and the outlet pipe 6b communicates with the water cooling chamber 4d.

Reference numeral 10 is a water tank for cooling water. A pipe 5a is connected between the water tank 10 and an inlet pipe 6a, and a pipe 5b provided with a pump 14 is connected between the water tank 10 and an outlet pipe 6b. A cooling water circuit is formed. Then, by the operation of the pump 14, the cooling water in the water tank 10 becomes
The water is circulated and supplied to the water cooling chambers 4a to 4d in sequence through a and 5b.

A cooling unit 8 for cooling the inside of the water tank is attached to the bottom of the water tank 10. The cooling unit 8 is controlled by a temperature controller 9 so that the temperature of the cooling water becomes a predetermined cooling temperature. Reference numeral 11 denotes a laser oscillator such as a YAG laser, which is arranged so as to emit the laser light L toward the incident side of the water-cooled filter device.

The attenuator thus constructed is arranged in front of the optical path of the laser oscillator 11 such as a laser beam machine,
It is used to drop high power laser light to low power.

While the laser oscillator 11 operates and irradiates the laser beam through the water-cooling type filter device, the pump 14 is operated and the cooling water in the water tank 10 is circulated in the water-cooling chambers 4a to 4d in order through the pipes 5a and 5b. -Supplied. As a result, the attenuation filter 2a is cooled by directly contacting the cooling water in the water cooling chambers 4a and 4b, and similarly, the attenuation filter 2b is contacted and cooled in the cooling water in the water cooling chambers 4b and 4c, and further, the attenuation filter 2a. 2c is cooled by coming into contact with the cooling water in the water cooling chambers 4c and 4d.

When the laser light emitted from the laser oscillator 11 passes through the respective attenuation filters 2a, 2b, 2c, it is gradually attenuated in a stepwise manner according to the transmittance of each filter. For example, each attenuation filter 2a , 2b, 2c are set to 50%, 50%, and 20%, the laser light transmitted through each attenuation filter is attenuated to a light amount of about 1/20.

The attenuating portion of the laser light is converted into heat energy and heats the attenuating filters 2a, 2b and 2c. The attenuating filters 2a, 2b and 2c are in contact with the cooling water flowing through the water cooling chambers 4a to 4d efficiently. To be cooled. Therefore, the temperature rise is prevented and the attenuation filters 2a, 2b, 2c are
It is possible to prevent the casing 1 from being damaged by heat.

Further, a plurality of attenuation filters 2a, 2b, 2
Since the laser light is attenuated stepwise by c and the attenuation filter 2c having a lower transmittance is arranged on the emission side,
It is possible to prevent the temperature of the filter from rising rapidly and to prevent the laser light from being damaged even when the laser light is attenuated at a relatively large attenuation rate.

Further, according to the experiment, when a laser beam with an output of 10 W is transmitted through an attenuation filter that does not perform water cooling,
Although the attenuating filter was damaged by irradiation for about 30 seconds, the attenuating filter was not damaged in the water-cooled filter device having the above configuration even when the laser beam with an output of 80 W was continuously transmitted to the attenuating filter for about 5 minutes. It was

As described above, since the laser light can be attenuated to an arbitrary low output by using the attenuation filter, the output of the laser oscillator of the laser processing machine or the like can be maintained at a high output that can obtain a stable output. It is possible to obtain a stable low-output laser light with little output fluctuation.

2 and 3 show a filter device according to another embodiment. This filter device has the same basic configuration as that of the above embodiment except that the casing 20 is divided.

That is, the casing 20 is formed by stacking cylindrical casing pieces 20a, 20b, 20c having short widths to form a casing portion for holding an attenuation filter, and at the outside (both sides) of the casing piece for holding transparent glass. 21a, 2
1b is assembled and formed into a cylindrical shape.

Each casing piece 20a, 20b, 20c is provided with a recess for fitting the attenuation filter 2a, 2b, 2c and a water channel for cooling water, and the recess has a peripheral edge of the attenuation filter 2a, 2b, 2c. The parts are fitted into each other and assembled so as to press the convex parts of the adjacent casing pieces from above. Then, in this state, the water channels in each casing piece are connected to each other to form the water channels 7a, 7b, 7c.

Further, a casing piece 21a for holding transparent glass is fitted on the outside of the casing piece 20a, and a similar casing piece 21b is fitted on the outside of the casing piece 20c. In that state, the long tightening bolts 27 are inserted into the holes provided at the edges of each casing piece,
0a, 20b, 20c, 21a, 21b are clamped and fixed to each other, and the casing is assembled.

Then, the transparent glass 3a is fitted inside the casing piece 21a, the transparent glass 3b is fitted inside the casing piece 21b, and ring-shaped ring screws 23a and 23b are screwed from the outside thereof, Transparent glasses 3a and 3b are attached to the outside (both sides) of the attenuation filter.

As a result, similarly to the above, a water cooling chamber 4a is formed between the transparent glass 3a and the attenuation filter 2a, and a water cooling chamber 4b is formed between the attenuation filter 2a and the attenuation filter 2b. Attenuation filter 2c
A water cooling chamber 4c is formed between them, and a water cooling chamber 4d is formed between the transparent glass 3b and the attenuation filter 2c.

An annular seal member 24a is inserted between the casing pieces 2a, 2b, 2c to form the transparent glass 3
A seal member 24b is fitted around the peripheral portions of a and 3b, and the joint is completely sealed. Also, one casing piece 2
1a is provided with an inlet pipe 26a for cooling water, and the other casing piece 21b is provided with an outlet pipe 26b.

In such a filter device, the casing 20 has casing pieces 20a, 20b, 20c, 21a,
The number of the casing pieces 20a, 20b, 20c for holding the attenuation filters, which are divided and formed by 21b, can be assembled in an arbitrary number according to the number of the attenuation filters to be used, so that the number of the attenuation filters to be used is arbitrarily determined. However, the amount of attenuation that attenuates the laser light can be set arbitrarily and easily.

The filter device having the above-mentioned structure is arranged on the optical path of the laser light emitted from the laser oscillator, and the cooling water circulation path is connected to the introduction pipe 26a and the discharge pipe 26b, and the pump 14 is introduced through the pump 14 as in the above-mentioned embodiment. The cooling water in the tank 10 is circulated and supplied to each of the water cooling chambers 4a to 4d, and the damping filter 2
It operates so as to attenuate the laser light while cooling a, 2b, and 2c with water.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a laser light attenuator according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a filter device in an attenuation device of another embodiment.

FIG. 3 is a front view of the filter device.

[Explanation of symbols]

1-casing, 2a, 2b, 2c-attenuation filter, 3a, 3b-transparent glass, 4a, 4b, 4c, 4d-water cooling chamber, 5a, 5b-piping, 8-cooling unit, 10-pump, 11-Laser oscillator.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michio Kameyama 1-1, Showa-machi, Kariya city, Aichi Japan Denso Co., Ltd. (56) Reference JP-A-4-15528 (JP, A) JP-A-56 -17092 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 5/00 G02B 5/18 G02B 5/20 H01S 3/00

Claims (4)

(57) [Claims] 1. A laser light attenuating device in which an attenuating filter is arranged in an optical path of laser light output from a laser oscillator, and the laser light is transmitted through the attenuating filter to be attenuated. Water cooling chambers for directly contacting water for cooling are provided before and after the attenuation filter ,
Multiple attenuating filters are placed side by side in the optical path at intervals.
And a water cooling chamber provided between the attenuation filters . 2. A laser beam attenuation device communicatively connected claim 1 in the cooling water circulation passage water-cooling chamber for circulating the cooling water in the water cooling chamber. 3. The laser light attenuation apparatus according to claim 2 , wherein a tank is provided in a part of the cooling water circulation path, and a cooling unit for cooling the cooling water in the tank is provided. 4. The plurality of attenuation filters are arranged in parallel in a cylindrical casing at intervals, and the casing is formed by combining a plurality of divided casing pieces, each of the plurality of casing pieces being an attenuation filter. laser light attenuating device structure as claims 1, wherein for holding.