JPH1152259A - Laser beam absorption structure and attenuator using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avert the trouble which occurs when a light absorber consisting of a carbon based material is directly irradiated with a high-energy laser beam, more specifically, the splashing of the carbon based material on the surface of the light absorber and the function hindrance of the light absorption effect and contamination of a peripheral atmosphere occurring therewith. SOLUTION: This laser beam absorption structure has the carbon based light absorber 1 which comprise the carbon based material and has the surface state for obtaining a laser beam absorption function and a translucent buffer member (fused quartz glass plate material) 2 which is disposed on the front surface side of this carbon based light absorber 1 and has a laser beam transmission characteristic and a laser beam impact buffer characteristic. The structure has also a translucent coating member (SiC) which coats the front surface side of the carbon based light absorber, has at least the laser beam transmission characteristic and executes the action to prevent the splashing of the carbon based material in place of the translucent buffer member 2. In addition, the laser beam absorption structure is applied to an attenuator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light absorbing structure and an attenuator using the same, and more particularly, to a problem that occurs when a light absorber made of a carbon-based material is directly irradiated with laser light. Regarding techniques to avoid.

[0002]

2. Description of the Related Art Generally, when an optical experiment or the like is performed using a laser beam, the laser beam is reflected by the optical device when an appropriate characteristic conversion is given to the laser beam using the optical device or the like. In some cases, unnecessary light that is emitted in a direction deviating from the original purpose may be generated. The unnecessary light is incident on other optical elements or the like, or adversely affects the surrounding environment, and is a factor that hinders a suitable optical experiment operation or the like.

In order to cope with such a situation, a light absorber having a laser light absorption characteristic is generally provided in the optical system of this type in the middle of the unnecessary light passage. . As a specific example of the light absorber, there is a carbon-based solidified or sintered body in which a surface portion is formed into a predetermined state for obtaining a laser light absorbing function. The unnecessary light is absorbed by the surface of the solidified material of this kind, so that the light is prevented from traveling at that position, and adverse effects on other optical elements and the surrounding environment are avoided.

On the other hand, when conducting an optical experiment or the like, it may be necessary to convert a laser beam emitted from a light source into required characteristics on the light receiving side in the middle of the optical path. As an example of such light characteristic conversion means, there is a case where an attenuator is provided in the optical path for the purpose of attenuating light intensity. The attenuators for attenuating light intensity are roughly classified into a fixed type in which the attenuation is maintained at a constant value and a variable type in which the attenuation can be changed.

[0005]

By the way, in recent years, with the transition of the purpose of use and the transition of the required level,
The fact is that higher energy of laser light is being promoted. In this case, the light absorber made of the carbon-based material exemplified above can be expected to exhibit its effect with respect to a relatively low-energy laser beam, but with respect to a high-energy laser beam, There is a problem that the light absorption function is hindered.

The problem will be described in detail. When high-energy laser light is irradiated on the surface of the light absorber made of the carbon-based material, the shock wave component of the laser light is large or the laser light is irradiated. Since the thermal stress caused by the temperature rise is large, the carbon-based particles on the surface of the light absorber are blown off and scattered. This causes not only the surrounding atmosphere to be contaminated, but also the surface portion to be eroded, so that the surface condition of the carbon-based light absorber can secure the original light absorption function. From an unexpected state, and the original function cannot be exhibited. As a result, not only does the durability of the carbon-based light absorber become a problem, but the light radiated to the light absorber is irregularly reflected on its surface, and is a factor that hinders good optical experiment work and the like. Becomes

Further, such a problem is caused in both the fixed type and the movable type attenuators exemplified above, when high-energy laser light is used, in the vicinity of the optical element which performs the light attenuating action. This is a prominent problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an adverse effect when a light absorber made of a carbon-based material is directly irradiated with a high-energy laser beam. It is an object of the present invention to avoid the scattering of the carbon-based material on the surface of the surface and the resulting impairment of the function of absorbing light and the contamination of the surrounding atmosphere.

[0009]

Means for Solving the Problems A laser light absorbing structure and an attenuator using the same according to the present invention have the following features in order to achieve the above technical object.

In other words, the invention according to the first aspect of the present invention relates to a carbon-based light absorber composed of a carbon-based material and having a surface state for obtaining a laser-beam absorbing function.
A light transmitting buffer member having at least laser light transmission characteristics and laser light shock mitigation characteristics disposed on the surface side of the carbon-based light absorber.

In the invention according to a second aspect of the present invention, the light transmitting buffer member is made of a fused silica glass plate.

[0013] On the other hand, the invention according to claim 3 relates to a carbon-based light absorber composed of a carbon-based material and having a surface state for obtaining a laser light absorbing function.
A light-transmitting coating member that is coated on the surface side of the carbon-based light absorber and has at least a laser light transmission property and performs a carbon-based material scattering prevention action.

Further, in the invention according to a fourth aspect of the present invention, the light-transmitting coating member is made of SiC and is coated on the surface of the carbon-based light absorber in close contact.

Further, in the invention according to the fifth aspect of the present invention, the cross-sectional shape of the surface portion of the carbon-based light absorber is such that triangles having a predetermined vertical angle are continuously arranged in a row. It has a waveform.

In addition, the invention according to a sixth aspect of the invention provides the attenuator in which the laser light absorbing structure according to the first, second, third, fourth or fifth aspect is disposed at a place where the absorption function is required. is there.

[0016]

According to the first aspect of the present invention, the high-energy laser light irradiated to the surface of the carbon-based light absorber is directed to the surface of the carbon-based light absorber. The light reaches the light transmitting buffer member provided. In this case, since the light transmitting buffer member has a laser light transmitting characteristic, the laser light passes through the light transmitting buffer member and reaches the surface of the carbon-based light absorber. When the laser light passes through the light transmitting buffer member, the incident angle of the laser light to the light transmitting buffer member is 90 ° so that reflected light is not generated or the reflected light is reduced as much as possible. Alternatively, it is preferable to set the angle to approximately 90 °. In addition, since the light transmitting buffer member has laser light shock mitigation characteristics, high energy laser light having a large shock wave component is reduced in its shock wave component by transmitting through the light transmitting buffer member. After that, it reaches the surface of the carbon-based light absorber.

In this case, since the surface of the carbon-based light absorber is formed in a state for obtaining a laser light absorbing function, the laser light reaching the surface absorbs the carbon-based light absorber due to the absorption function. Appropriately absorbed by the light absorber.
Since the laser light has a reduced shock wave component as described above, the carbon-based particles do not blow off from the surface portion of the carbon-based light absorber and are not scattered, so that the surface portion may be eroded. Cannot occur. For this reason, the surface state of the carbon-based light absorber can maintain the state for obtaining the initial laser light absorption function, and the original function can be continuously exhibited. As a result, it is possible to avoid such a problem that a laser beam applied to the carbon-based light absorber is irregularly reflected on the surface of the carbon-based light absorber, thereby hindering a favorable optical experiment operation.

According to a second aspect of the present invention, a fused quartz glass plate is used as the light transmitting buffer member, and the fused quartz glass plate has both laser light transmission characteristics and laser light shock mitigation characteristics. It has characteristics. Therefore, if this fused quartz glass plate is used, the same operation and effect as the case of the invention described in claim 1 can be obtained. Further, since the fused quartz glass plate material also has excellent heat resistance, even if the temperature rises due to the irradiation of the laser beam, there is no possibility of causing trouble such as damage or breakage.
In this case, sapphire glass, diamond, or the like can be used as a material capable of obtaining the same operation and effect as the above fused silica glass material.

On the other hand, according to the invention described in claim 3,
The high-energy laser light directed toward the surface of the carbon-based light absorber passes through the light-transmitting covering member and reaches the surface of the carbon-based light absorbing member. Because of the transmission characteristics, the same transmission characteristics can be said to be the same as those described in the first aspect of the present invention.

In addition, since the light-transmitting coating member covers the surface side of the carbon-based light absorber and performs an action of preventing scattering of the carbon-based material, the surface of the carbon-based light absorber has high energy. Even if a large thermal stress occurs on the surface of the carbon-based light absorber due to the arrival of the laser light, the surface of the carbon-based light absorber is solidified by being firmly covered by the light-transmitting coating member. In state. Therefore, the carbon particles do not blow off and scatter from the surface,
Since the surface portion cannot be eroded, the surface state of the carbon-based light absorber can maintain the state for obtaining the initial laser light absorption function, and perform appropriate optical experiment work and the like. The adverse effects at the time are eliminated.

According to the fourth aspect of the present invention, as the light-transmitting covering member, a member made of SiC and coated on the surface of a carbon-based light absorber is used. In addition to having light transmission characteristics, it has excellent strength and heat resistance, and is also in close contact with the surface of the carbon-based light absorber, so that it is possible to suitably prevent the scattering of carbon-based materials. It is. Therefore, by using this SiC coating means, the same effect as in the case of the invention described in claim 3 can be obtained with respect to the prevention of carbon-based particle scattering.

As described above, the first and second aspects of the present invention address the situation where the surface portion of the carbon-based light absorber is eroded by the shock wave component of the high energy laser light. On the other hand, the inventions described in the third and fourth aspects deal with a situation in which the surface portion of the carbon-based light absorber is eroded due to an increase in thermal stress accompanying irradiation of the high-energy laser light. As described above, the two types of countermeasures exist because the cause of erosion of the carbon-based light absorber differs depending on the difference in the characteristics of the laser beam.

On the other hand, according to the invention described in claim 5, the cross-sectional shape of the surface portion of the carbon-based light absorber is such that triangles whose apex angle is a predetermined angle (for example, an angle of 90 ° or less) are continuously arranged in a row. With such a waveform, the laser beam incident at right angles or substantially at right angles to the surface portion of the carbon-based light absorber is alternately and repeatedly reflected a plurality of times on the opposing inclined surface of the above-mentioned triangle. In this case, the reflected light travels toward the bottom of the valley between the opposed slopes for geometric reasons. For example, when the apex angle is 30 °, the reflected light travels until reflection is performed three times. Does not cause a situation in which reflected light is emitted from the surface toward the side opposite to the incident direction. Therefore, the laser light incident on the surface portion of the carbon-based light absorber is suitably absorbed while being reflected a plurality of times (three times in the above example).

Further, the invention described in claim 6 is the one in which the laser light absorbing structure according to any one of claims 1 to 5 is applied to an attenuator that performs a light intensity attenuation function.
The laser light absorbing structure is provided at a portion of the attenuator that requires its absorption function. Specifically, when an optical element in the attenuator, which performs an optical intensity attenuating action, is irradiated with laser light, the optical element is disposed at a position where unnecessary laser light reflected by the optical element can be received. Therefore, in this case, the same operation and effect as described above can be obtained for the attenuator. In this case, the laser light absorbing structure described above can be applied to both a fixed type and a movable type as the attenuator.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a laser beam absorbing structure according to the present invention and an attenuator using the same will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing a laser light absorbing structure according to a first embodiment of the present invention. As shown in FIG. 1, the laser light absorbing structure includes a carbon-based light absorber 1 made of a carbon-based material, and a light-transmitting buffer member 2 disposed on the surface side of the carbon-based light absorber 1. And a bent holding plate 3 for holding the above both in a fixed state. in this case,
It is preferable to provide a predetermined gap between the outermost surface of the carbon-based light absorber 1 and the back surface of the light transmitting buffer member 2.

The carbon-based light absorber 1 is made of a solid or sintered body made of carbon or carbon fiber, or a C / C composite (made by Toyo Carbon Co., Ltd.) made of a carbon-based composite material. The cross-sectional shape of the surface portion of the carbon-based light absorber 1 exhibits a waveform in which triangles having a vertical angle of a predetermined angle are continuously arranged in a row. In this case, as shown in FIG. 2, if the apex angle A is, for example, 30 °, the laser beam X incident on the surface at a right angle or substantially at a right angle will be reflected on the opposing inclined surfaces 1a, 1a of the adjacent triangle. It is reflected alternately and repeatedly. The laser beam X is in a direction opposite to the incident direction (a direction) until the reflection is repeated three times.
Without going back to the bottom of the triangle. As a result, the laser beam X is subjected to an extreme light absorbing effect during the above-mentioned three reflections, and is compared with a case where the laser beam is irradiated only once on the surface of the carbon-based light absorber 1. As a result, the laser beam X is reliably absorbed with a better action.

The apex angle A of the triangle is 30 °.
For example, when the apex angle A is set to 20 °, the number of times of repetition of reflection without returning to the direction a is four, that is, the opposing slope 1 of the adjacent triangle.
It suffices that the angle is such that the laser beam X repeats the reflection two or more times without returning to the a direction in the directions a and 1a. In addition, even if the surface portion of the carbon-based light absorber 1 does not have a triangular waveform as described above, for example, it may have a flat shape without luster, or may have only a slight unevenness, Depending on the energy level of the laser beam, it is possible to have a sufficient laser light absorbing function.

On the other hand, the light transmitting buffer member 2 is made of a fused silica glass plate. The fused quartz glass plate 2 has excellent heat resistance in addition to having laser light transmission properties and laser light shock mitigation properties.
Therefore, the laser beam having high energy applied toward the surface side of the carbon-based light absorber 1 first transmits through the fused silica glass plate material 2 to reduce its shock wave component, and then absorbs the carbon-based light. It is incident on the surface of the body 1. Since the surface of the carbon-based light absorber 1 is formed into a shape for obtaining a laser light absorbing function as described above, laser light incident on the surface of the carbon-based light absorber 1 In addition to being reliably absorbed inside the system-based light absorber 1, the laser beam has a reduced shock wave component as described above, so that a large impact force of the laser light is applied to the surface of the carbon-based light absorber 1. The carbon-based particles are not blown off from the part and are not scattered, and therefore, a situation in which the surface portion is eroded cannot occur.

Thus, the surface shape of the carbon-based light absorber is
The original shape for obtaining the laser light absorbing function can be maintained, and the original function can be continuously exhibited. As a result, the durability of the carbon-based light absorber is improved, and the laser light applied to the light absorber is irregularly reflected on the surface of the light absorber. Will be avoided.

Since the fused quartz glass plate 2 also has excellent heat resistance, even if the temperature rises due to the irradiation of the laser beam, there is no danger of causing damage or breakage. In this case, sapphire glass, diamond, and the like can be used as materials capable of obtaining the same operational effects as the above fused silica glass material. However, in view of cost, a fused silica glass material is advantageous.

FIG. 3 is an enlarged vertical sectional front view showing a laser light absorbing structure according to a second embodiment of the present invention. As shown in the figure, the laser light absorbing structure includes a carbon-based light absorber 10 having the same configuration as that of the first embodiment, and a light-transmitting covering member 20 coated on the surface side. . And
In this case, it is not necessary to dispose the above-mentioned light transmitting buffer member (fused quartz glass plate material) on the surface side.

The light-transmitting coating member 20 is made of SiC and has high adhesion with the carbon-based light absorber 10.
The surface is coated. The translucent coating member 20 made of SiC has a laser light transmission characteristic and also has a function of preventing the carbon-based light absorber 10 from scattering carbon-based particles. Further, as a characteristic for performing a carbon-based particle scattering prevention action, the light-transmitting coating member 20 made of SiC is used.
Has high strength and high heat resistance, so that the surface of the carbon-based light absorber 10 is firmly solidified by the light-transmitting covering member 20 so as not to swell independently.

Accordingly, the high-energy laser light reaches the surface of the carbon-based light absorber 10 via the light-transmitting coating member 20 made of SiC, and causes a large thermal stress on the surface of the carbon-based light absorber 10. Occurs, the surface portion of the carbon-based light absorber 10 is firmly covered with the light-transmitting covering member 20, so that the carbon-based particles do not blow off and scatter from the surface portion. It is not possible for parts to erode. Therefore, the carbon-based light absorber 1
The surface state of 0 can maintain the initial state for obtaining the laser light absorbing function, and the harmful effects in performing an appropriate optical experiment work or the like are eliminated. Although the translucent covering member 20 is made of SiC, it is also possible to use another material whose strength and durability are equivalent or slightly inferior thereto.

FIG. 4 is a schematic plan view showing a state in which the laser light absorbing structure according to the first embodiment is applied to a movable attenuator which performs light intensity attenuating action. As shown in the drawing, the attenuator 50 includes two optical element groups 51, 51, 5
2, 52. The two optical element groups are configured to rotate in mutually opposite directions in the angular range between the state shown by the solid line and the state shown by the chain line, and the attenuation rate of the light intensity is changed according to the difference between the rotation angles. Changes. In this embodiment, the optical elements 51, 5
Reference numerals 1, 52, and 52 are made of a fused silica glass plate. The laser beam Y that passes through the two optical element groups and travels in a straight line becomes useful light used for various measurements by irradiating the sample, for example. The laser light X reflected by the element group is unnecessary light that is irradiated toward the worker or hinders the various measurements.

Therefore, the attenuator 50 is provided with a laser light absorbing structure for absorbing the unnecessary light at each required position. Specifically, a total of four laser light absorbing structures 1, 2, and 3 are arranged as one set of optical elements, and these are fixed to a mounting frame 53 to form a unit, which is detachably attached to a casing. The configuration is as described above. In this case, care is taken so that the unnecessary reflected laser light X is incident on the surfaces of the laser light absorbing structures 1, 2, and 3 at substantially right angles. In order to make the unnecessary reflected laser beam X incident on the surface of each laser light absorbing structure at a right angle with accuracy at a location, it is conceivable to configure each laser light absorbing structure to rotate in conjunction with the rotation of the optical element. Can be

FIG. 4 shows a state in which the laser light absorbing structure according to the first embodiment is applied to an attenuator, but the laser light absorbing structure according to the second embodiment is replaced with the same structure. Naturally, it is also possible to apply to the attenuator.

FIG. 4 shows a state in which the laser light absorbing structure is applied to a movable type attenuator. However, it goes without saying that the present invention is also applicable to a fixed type attenuator.

Further, in the above embodiment, the laser light absorbing structure is applied to an attenuator. However, the laser light absorbing structure may be applied to another optical device such as a spectroscope instead. It is.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a first embodiment of a laser light absorbing structure according to the present invention.

FIG. 2 is an enlarged vertical sectional front view of a main part showing a first embodiment of the laser light absorbing structure according to the present invention.

FIG. 3 is an enlarged longitudinal sectional front view of a main part showing a second embodiment of the laser light absorbing structure according to the present invention.

FIG. 4 is a schematic plan view showing a state in which the first embodiment of the laser light absorbing structure according to the present invention is used for an attenuator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 carbon-based light absorber 2 translucent buffer member (fused quartz glass plate material) 10 carbon-based light absorber 20 translucent covering member (SiC) 50 attenuator

Claims (6)

[Claims] 1. A carbon-based light absorber composed of a carbon-based material and having a surface state for obtaining a laser light absorption function, and provided at least on a surface side of the carbon-based light absorber to transmit at least laser light. And a light transmissive buffer member having laser light shock mitigation characteristics. 2. The laser light absorbing structure according to claim 1, wherein the light transmitting buffer member is a fused silica glass plate. 3. A carbon-based light absorber composed of a carbon-based material and having a surface state for obtaining a laser light-absorbing function, and coated on the surface side of the carbon-based light absorber to have at least laser light transmission characteristics. And a light-transmissive coating member having a carbon-based material scattering prevention function. 4. The laser beam absorbing structure according to claim 3, wherein the translucent covering member is made of SiC and is coated in close contact with the surface of the carbon-based light absorber. 5. A sectional shape of a surface portion of the carbon-based light absorber is as follows:
4. The laser beam absorbing structure according to claim 1, wherein the laser beam absorbing structure has a waveform in which triangles having a vertical angle of a predetermined angle are arranged in a continuous manner. 6. An attenuator characterized in that the laser light absorbing structure according to claim 1, 2, 3, 4, or 5 is provided at a place where the absorbing function is required.