JP2599463Y2 - Laser focus position fluctuation measurement device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION An optical device for supplying laser light to an optical fiber for laser processing, a laser condensing position fluctuation measuring device used in an optical device using laser light such as a laser processing nozzle, And the focusing position and shape of the laser light,
The present invention relates to a laser beam fluctuation measurement device that measures intensity and the like.

[0002]

2. Description of the Related Art In a laser processing nozzle, it is necessary to accurately and stably focus a laser beam on a processing point in order to perform processing with high energy efficiency and high accuracy. Further, in an apparatus for laser processing, it is necessary to guide a laser beam so that energy loss does not occur in an optical fiber that supplies laser light to a laser processing nozzle. For that purpose, it is necessary to converge the laser beam accurately and stably for a long time at the center of the end face of the optical fiber. As described above, in the field of laser processing, a technique for stably focusing a laser beam at a predetermined position is an important key.

[0003] The fluctuation of the focusing position of the laser beam is one manifestation of a phenomenon called drift. It is considered that the drift is mainly caused by a temperature change occurring with the elapse of the processing time during laser processing. Specifically, this drift is caused by a change in the resonator length of the laser oscillator due to a rise in temperature, a change in the length or angle between optical elements in an optical system including optical elements such as a mirror and a condensing lens, and further, a laser. This is caused by a change in the refractive index due to gas floating in the space through which the beam passes. When such a drift occurs, the condensing position of the laser beam fluctuates not only in the optical axis direction but also in a plane perpendicular to the optical axis.

Conventionally, in the case of a laser processing nozzle, an apparatus or method having the following configuration has been used to stably supply a laser beam to a processing point.

(1) A well-known beam measuring apparatus that rotates a wire at a laser beam condensing position and obtains a condensing position by reflected light from the wire.

(2) As shown in FIG. 8, the distance between the laser oscillator beam extraction port and the condenser lens 84 is obtained by calculation in the device 83 based on the signal from the NC device 82, and based on the calculation result. Processing apparatus that keeps the converging spot constant (Japanese Patent Laid-Open No. 60-187492).

(3) As shown in FIG. 9, a method of measuring the intensity of reflected light from a processing point by using a power sensor 87 so that the converging point of the laser beam coincides with the processing point -23092).

(4) As shown in FIG.
8, the distance between the processing head 89 and the processing point is measured, and based on this, the focal point of the laser beam is made to coincide with the processing point (Japanese Patent Application Laid-Open No. H3-110091).

(5) As shown in FIG. 11, a measuring laser beam 98 is provided separately from the processing laser beam by the focusing lens 9.
7, the amount of thermal deformation of the condenser lens 97 is measured, and based on the measurement result, the position of the condenser lens 97 is adjusted so that the focal point of the processing laser beam coincides with the processing point. (Japanese Patent Application Laid-Open No. 61-137693).

[0010]

However, the configuration of (1) above seeks the focus position of the laser beam prior to laser processing, and cannot adjust the focal position during laser processing. Therefore, there is a problem that if a drift occurs as the processing time elapses, the processing must be interrupted and the wire must be rotated again to adjust the focal position.

In the configuration of (2), only the distance between the laser oscillator beam extraction port and the condenser lens is specified, and when the drift occurs as described above and the characteristics of the laser beam itself change, However, there is a problem that the focal point of the laser beam cannot be matched with the processing point.

Further, the configuration (3) has the following problems. That is, at the processing point, plasma is generated by irradiation of a high-energy processing laser beam. Due to the influence of the plasma and disturbance light, even if the intensity of the reflected light from the processing point is measured, it is not possible to accurately know the condensing position of the laser beam.

In the configuration (4), only the distance between the processing head and the processing point is measured. As in the case of the above (2), when the drift occurs to change the characteristics of the laser beam itself. However, the focal point of the laser beam cannot be matched with the processing point.

In the configuration of (5), although drift due to thermal deformation of the condenser lens is eliminated, it is not possible to cope with other drifts due to, for example, a change in the resonator length.

Further, the above configurations (1) to (5) have a problem that fluctuations in laser beam intensity, laser beam diameter, and the like at a processing point caused by drift cannot be measured.

The present invention solves such a conventional problem at a glance, and an object of the present invention is to measure a change in the focusing position of a laser beam while using the laser beam. An object of the present invention is to provide a laser condensing position fluctuation measuring device. Another object of the present invention is to provide a laser beam capable of measuring a change in a focused position of the laser beam, a change in the size of the focused beam, and a variation in the focused beam intensity using the laser beam. It is to provide a fluctuation measuring device.

[0017]

According to the present invention, there is provided a laser condensing position fluctuation measuring apparatus in which a laser beam emitted from a laser light source device having a laser oscillator is condensed to a predetermined condensing position by a condensing optical system. A laser light condensing position fluctuation measuring device used in an optical device to be used and measuring the fluctuation of the light condensing position while using the laser beam. A monitor means for extracting a part of the laser beam as monitor light in an optical path, and a light-condensing position fluctuation detecting means for detecting a fluctuation of the light-condensing position based on the monitor light.

In the above arrangement, the monitor means is a reflection member provided between the light-collecting optical system and the light-collecting position, and the light-condensing-position fluctuation detecting means detects the light from the reflection member. And a plurality of optical sensors for detecting the reflected light of the optical sensors, and a change in the light condensing position is measured by a change in the intensity of light at each of the optical sensors.

The monitor means is provided between the condensing optical system and the condensing position, and takes out a part of the laser beam as monitor light to a condensing point different from the condensing position. A reflection member for condensing light, wherein the light-condensing position fluctuation detecting means is disposed at a light-condensing point of the monitor light, and detects a fluctuation of the light-condensing position of the laser beam by a fluctuation of the light condensing point of the monitor light. It can also be configured to be a beam position detecting device that performs the above.

Further, the monitor means is a reflection member provided between the laser light source device and the condensing optical system for extracting a part of the laser beam as monitor light. Means, a monitor light condensing optical system for condensing monitor light from the reflection member, and a light condensing position of the laser beam, which is disposed at a light condensing point of the monitor light, and which varies the light condensing point of the monitor light. It can also be constituted by a beam position detecting device for detecting fluctuation.

The laser beam fluctuation measuring device according to the present invention is used in an optical device which uses a laser beam emitted from a laser light source device having a laser oscillator by condensing it with a converging optical system. A laser beam fluctuation measurement device that measures the fluctuation of the focal position of the laser beam by the optical system, the fluctuation of the size of the focused beam, and the fluctuation of the focused beam intensity using the laser beam,
Monitoring means for extracting a part of the laser beam as monitor light in an optical path from the laser light source device to the light condensing position; light separating means for separating the monitor light into a plurality of measurement lights; A beam intensity variation measuring means for measuring a variation in the intensity of the laser beam at the focusing position from one of them, and a focusing device for detecting a variation in the focusing position from the other one of the measurement lights. Position change detection means;
Laser beam size variation measuring means for measuring the size variation of the focused beam spot at the focusing position by detecting the size of the laser beam from yet another one of the measurement lights. It is characterized by having.

[0022]

In the laser condensing position fluctuation measuring device having the above-mentioned configuration, a laser beam emitted from a laser light source device constituted by a laser oscillator, an optical lens and the like is condensed to a predetermined condensing position by a condensing optical system. Used in optical devices to light. The end face of the optical fiber, the object to be processed, and the like are arranged at the laser beam condensing position. Further, the laser condensing position fluctuation measuring device of the present invention measures the fluctuation of the condensing position of the laser beam in process, that is, using this laser beam. For example, when the measuring device of the present invention is used for an optical device that focuses a laser beam on the end face of an optical fiber, a change in the focus position is measured while actually supplying a laser beam to the end face of the optical fiber. When the measuring device of the present invention is used for a laser processing device, the fluctuation of the light-collecting position is measured while actually performing the processing.

The laser condensing position fluctuation measuring device of the present invention has a laser beam monitoring means, and this monitoring means monitors a part of the laser beam in the optical path from the laser light source device to the condensing position. Take it out as light. This monitor light is guided to the focus position change detecting means, where the change in the focus position is detected.

The monitor means is constituted by one or two or more reflecting members provided between the condensing optical system and the condensing position,
The light condensing position variation detecting means can be constituted by a plurality of optical sensors for detecting the reflected light from the reflecting member.
In this configuration, the fluctuation of the light condensing position is measured by the fluctuation of the light intensity (including the fluctuation from the light-off state to the light-on state) in each optical sensor. That is, the variation in the light intensity detected by each optical sensor can be used to measure the variation in the optical axis direction of the condensing position, and the position of the optical sensor that has detected the variation in the light intensity is perpendicular to the optical axis. It is possible to measure the fluctuation of the light condensing position in a complicated plane.

Further, the reflection member as the monitor means is a reflection member for condensing the reflected light at a light condensing point different from the light condensing position, and the light condensing position fluctuation detecting means is provided at the light condensing point of the monitor light. In the case of using the beam position detecting device, the position and size of the spot of the incident light can be detected by the beam position detecting device. In this configuration, the monitor light reflects the change in the focusing position of the laser beam actually used as it is. Therefore, the fluctuation of the condensing position of the laser beam in the optical axis direction is measured as a change in the spot size of the monitor light in the beam position detecting device. Further, the fluctuation of the laser beam condensing position in a plane perpendicular to the optical axis is measured as the fluctuation of the spot position of the monitor light in the beam position detecting device.

Further, a reflecting member provided between the laser light source device and the condensing optical system is used as the monitor means, and the condensing position fluctuation detecting means is used as a monitor condensing optical system for condensing monitor light from this reflecting member. And the above-mentioned beam position detecting device, the monitor light is taken out before passing through the condensing optical system, so that the monitor light is condensed on the beam position detecting device by the monitor condensing optical system. There is a need.
As described above, the beam position detecting device measures the fluctuation of the laser beam condensing position in the optical axis direction and the fluctuation in a plane perpendicular to the optical axis.

The laser beam fluctuation measuring device of the present invention is used in an optical device for condensing a laser beam at a predetermined light condensing position by a light condensing optical system, similarly to the aforementioned laser light condensing position fluctuation measuring device. In-process measurement of a change in the focused position of the laser beam, a change in the size of the focused beam, and a change in the intensity of the focused beam. In this laser beam fluctuation measuring device, the monitoring means extracts a part of the laser beam in the optical path from the laser light source device to the focusing position as monitor light. The extracted monitor light is separated into a plurality of measurement lights by a light separating unit. The beam intensity fluctuation measuring means uses one of these measuring lights,
The fluctuation of the intensity of the incident laser beam is measured. The other one of the measurement lights is used for detecting a change in the light condensing position by the light condensing position fluctuation detecting means. Further, the other one of the measurement lights is used for measuring a change in the size of the focused beam at the focusing position by the laser beam size variation measuring means.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 (a) shows a cross-sectional configuration of a laser condensing position fluctuation measuring apparatus according to a first embodiment of the present invention. The laser condensing position fluctuation measuring apparatus of this embodiment adjusts a high-output carbon dioxide laser 1 and a laser beam emitted from the high-output laser 1 to a predetermined beam diameter substantially parallel to the optical axis X. The optical device includes a telescope 2 that converts the laser beam B into a converted laser beam B, and a bending mirror 3 that causes the laser beam B from the telescope 2 to enter a condenser lens 4. In this embodiment, a high-power laser oscillator 1 and a telescope 2 constitute a laser light source device, and a condenser lens 4 functions as a condenser optical system. The condensing lens 4 condenses the laser beam B incident as a substantially parallel light beam on a converging position P on the optical axis X. At the light condensing position P, an end face of the optical fiber, an object to be processed, and the like are placed.

Further, in this embodiment, between the condensing lens 4 and the condensing position P, the four first light sources shown in the plan view of FIG.
Knife edge reflectors 5a to 5d are provided. In the present embodiment, these first knife edge reflectors 5a to 5d
And second knife-edge reflecting plates 7a to 7d described later function as monitoring means. The first knife edge reflectors 5a to 5d are arranged at positions surrounding the optical axis X in a plane perpendicular to the optical axis X, and when the laser beam B is converged toward a normal condensing position P. Is disposed without touching it and at a position very close to the laser beam B. Also, the first knife edge reflectors 5a to 5d
Below the four first reflecting plates 5a to 5d.
Optical sensors 6a to 6d are provided. In the present embodiment, these first optical sensors 6a to 6d and second optical sensors 8a to 8d described later function as light-condensing position fluctuation detecting means. The first optical sensors 6a to 6d deviate from the normal position where the condensing position P of the laser beam B deviates from the normal position.
When the laser beam B is applied to the laser beam, it is arranged at a position where the reflected light can be detected.

Below the first optical sensors 6a to 6d, four second knife edge reflectors 7a to 7d corresponding to the respective optical sensors 6a to 6d are provided. These second knife edge reflectors 7a to 7d are connected to the first knife edge reflector 5
a to 5d are provided at positions translated in a downward direction along the optical axis X, and the first knife edge reflectors 5a to 5d move the optical axis X
It is arranged at a position close to. Below the second knife edge reflectors 7a to 7d, the respective reflectors 7a to 7d
, Four second optical sensors 8a to 8d are arranged. These second optical sensors 8a to 8d detect reflected light when the laser beam B is applied to the second knife edge reflectors 7a to 7d when the condensing position P of the laser beam B deviates from a normal position. It is arranged at a position where it can be detected.

The laser condensing position fluctuation measuring device of the present embodiment functions as follows. First, a laser beam B emitted from a laser oscillator 1 is adjusted to a predetermined beam diameter by a telescope 2 and emitted toward a bending mirror 3 as a laser beam B substantially parallel to an optical axis X.
The laser beam B reflected by the bending mirror 3 enters the condenser lens 4 and is further condensed at a predetermined condensing position P. At this time, the beam diameter of the laser beam B is adjusted by the telescope 2 so that the focused laser beam B is not irradiated to the first knife edge reflectors 5a to 5d. If the laser beam B to be focused is on the first naf edge reflector 5
When the light is irradiated on the light sources a to 5d, the light can be detected by the first optical sensors 6a to 6d as shown in FIG. The second knife edge reflectors 7a to 7d and the second optical sensors 8a to 8d are also used as initial alignment detectors for making the laser beam B coincide with the direction of the optical axis X. That is, when the central axis of the laser beam B does not coincide with the optical axis X, the laser beam B
When the light is applied to any of the knife edge reflectors 7a to 7d, the reflected light is detected by any of the second optical sensors 8a to 8d.

When the laser beam B is condensed at the correct condensing position as described above, the end face of the optical fiber, the object to be processed, etc. are placed at the converging position P, and the laser beam B is actually used. Then, drift occurs with the passage of time, and for example, as shown in FIG. 1B, the diameter of the laser beam B fluctuates so as to increase, and the light condensing position P moves on the optical axis X to the second knife edge reflector. 7A to 7D, a part of the laser beam B is changed to the first knife edge reflectors 5a to 5d.
And the reflected light is used as monitor light for each of the first
The light enters the optical sensors 6a to 6d. From the light detection signals of the first optical sensors 6a to 6d, it is possible to know that the laser beam B has deviated from the normal focus position P due to drift.

When the focal position P of the laser beam B fluctuates in a plane perpendicular to the optical axis X, that is, deviates from the optical axis X, the first knife edge reflectors 5a to 5d or the The laser beam B is reflected by the two-knife-edge reflectors 7a to 7d, and the reflected light becomes monitor light. In this case, the first knife edge reflectors 5a to 5d
Or the second knife-edge reflectors 7a to 7
The laser beam B is not reflected on all of the laser beams d, but some of the first knife edge reflectors 5a to 5d or some of the second knife edge reflectors 7a to 7d monitor the laser beam B. As a reflection. Therefore, by knowing which optical sensor has detected the monitor light, it is possible to know in which direction the laser beam B has shifted from the optical axis X.

As described above, when the laser condensing position fluctuation measuring apparatus of this embodiment is used, the fluctuation of the condensing position P of the laser beam B can be detected in process. When a change in the light collecting position P is detected, the telescope 2 adjusts the beam diameter of the emitting laser, adjusts the optical axis, and the like so as to eliminate the change. It is controlled so as not to fluctuate from the position.

In this embodiment, the case where four first and second knife edge reflectors and four first and second optical sensors are arranged around the optical axis X has been described. However, the present invention is not limited to this. Not something. Also, for example, instead of the first and second knife edge reflectors, as shown in FIG. 1D, the same as the first knife edge reflectors 5a to 5d or the second knife edge reflectors 7a to 7d, respectively. A donut-shaped reflecting member 15 having a cross section is used.
It is also possible to adopt a configuration in which the reflected light from the reflecting surface 15a is detected at a plurality of locations by an optical sensor. In this embodiment, the case where the carbon dioxide laser 1 is used has been described. However, the present invention can be applied to the case where another laser is used.

FIG. 2A shows a cross section of a laser processing apparatus using a laser condensing position fluctuation measuring apparatus according to a second embodiment of the present invention. FIG. 2B is a cross-sectional view taken along line AA of FIG. The laser condensing position fluctuation measuring device of the present embodiment is provided on a processing nozzle of a laser processing device. This laser processing apparatus is similar to the first embodiment,
It has a high-power laser oscillator 1, a telescope 2, a bending mirror 3, and a condenser lens 4. The laser beam B that has passed through the condenser lens 4 has an optical axis X outside the opening at the tip of the laser processing nozzle 12. Light is condensed on the upper light condensing position P. A gas supply line 13 is provided on a side of the laser processing nozzle 12, and a processing gas is supplied from the gas supply line 13. The condenser lens 4 is supported by a support member 11 provided above a laser processing nozzle 12. In the present embodiment, as shown in FIG. 2B, four knife edge reflectors 9a are provided inside a laser processing nozzle 10.
To 9d, and optical sensors 10a to 10d corresponding to the respective knife edge reflectors 9a to 9d are provided below.

In this embodiment, similarly to the first embodiment, when the condensing position P of the laser beam B fluctuates on the optical axis X, and in a plane perpendicular to the optical axis X, When it fluctuates, the laser beam B on the knife edge reflectors 9a to 9d
Reflected light enters the optical sensors 10a to 10d as monitor light. By detecting this monitor light, it is possible to measure the fluctuation of the light condensing position P.

FIG. 3 shows a schematic configuration of a laser condensing position fluctuation measuring apparatus according to a third embodiment of the present invention. In this embodiment, a part of the laser beam B before being incident on the condenser lens 4 is extracted as monitor light M. That is, the condenser lens 4
The reflection member 21 reflects only the light on the outer periphery of the substantially parallel laser beam B before being incident as the monitor light in the direction of the optical axis X ′. The reflection member 21 is shown in FIG.
This is a reflecting mirror having the shape shown in (a), and has an opening 22 in the center. The laser beam B is applied to a portion shown by a broken line in FIG. Therefore, the laser beam B passing through the aperture 22 is less affected by the reflecting member 21 and is focused on the focusing position P on the optical axis X, so that the monitor beam is hardly disturbed by the laser beam B. Can be taken out.

The monitor light extracted by the reflecting member 21 is condensed on a condensing point Q on the optical axis X 'via a monitor condensing lens 23 functioning as a monitor condensing optical system. A beam position detecting device 24 made of a semiconductor element is arranged at the light condensing point Q. FIG. 5A is a plan view of the beam position detecting device 24 used in this embodiment. The beam position detection device 24 detects a change in the position of the irradiation laser focused beam spot S from the center (the intersection of the x axis and the y axis) and the size of the irradiation beam.

In this embodiment, since the converging position P of the laser beam B is reflected on the converging point Q of the monitor light, the fluctuation of the converging position P is measured by measuring the fluctuation of the converging point Q. Can be. That is, since the change of the light condensing position P in the direction of the optical axis X appears as the change of the light condensing point Q in the direction of the optical axis X ′, it can be regarded as the change of the size of the beam spot S. Further, a change in the light condensing position P in a plane perpendicular to the optical axis X can be captured as a change in the spot S on the xy plane on the beam position detecting device 24.

In this embodiment, the reflecting member 21 is
For example, one having another configuration shown in FIGS. 4B to 4D can be used. The reflecting member shown in FIG.
This is a beam splitter composed of a semi-transmissive mirror having a very low reflectance (for example, about 1%), and extracts a part of the laser beam B applied to a portion indicated by a broken line in FIG. The reflection member shown in FIG. 4C has the laser beam B in only four portions of the outer peripheral portion of the laser beam B.
Is reflected, and the amount of monitor light in FIG. 4A is reduced. The reflection member shown in FIG. 4D has a knife edge at the reflection portion of the laser beam B in FIG. 4C, and further reduces the amount of monitor light.

In the configuration of this embodiment, a beam position detecting device 24 using a pyroelectric element or a plurality of thermocouples 25 as shown in FIG. It is also possible to use the one that was used.

FIG. 6 shows a schematic configuration of a laser condensing position fluctuation measuring apparatus according to a fourth embodiment of the present invention. In this embodiment, the monitor light is extracted by the reflecting member 31 provided between the condenser lens 4 and the condenser position P. Reflective member 3
As 1, the same one as shown in FIGS. 4A to 4D can be used. In this embodiment, the monitor light is extracted after passing through the condenser lens 4, so that
As in the third embodiment (FIG. 3), the monitor light is focused on the focusing point Q without providing an optical system for focusing the monitor light. A beam position detecting device 34 similar to the above-described beam position detecting device of FIG.

Also in this embodiment, the optical axis X of the light condensing position P
The change in direction and the change in a plane perpendicular to the optical axis X can be captured by the beam position detecting device 34.

FIG. 7 shows a plan view of a laser beam fluctuation measuring apparatus according to a fifth embodiment of the present invention. The above first to fourth
Although the laser condensing position fluctuation measuring device of the embodiment measures only the fluctuation of the converging position P of the laser beam B, the laser beam fluctuation measuring device 40 of the present embodiment In addition to the fluctuation, the fluctuation of the light intensity of the laser beam B can be measured. In this embodiment, a case where a laser beam is introduced into an optical fiber of a laser processing apparatus will be described.

The laser beam fluctuation measuring device 40 of the present embodiment
Then, the incident laser beam B introduced via a high-power laser oscillator, a telescope, a bending mirror, etc.,
It is incident in the direction of the optical axis X shown in FIG. A part of the incident laser beam B is extracted in the direction of the optical axis X ′ as monitor light M by a beam splitter 41 composed of a semi-transmissive mirror similar to that shown in FIG. The reflectivity of the beam splitter 41 is about 1%. In this embodiment, FIG.
Although the semi-transmissive mirror shown in (b) is used as the beam splitter 41, the one shown in FIGS. 4 (c) to (d) may be used instead.

In this embodiment, the laser beam B
A shutter 42 is provided for turning on and off the introduction of. The laser beam B transmitted through the beam splitter 41 is reflected by the total reflection mirror 43 in the direction of the condenser optical system 44. The condensing optical system 44 includes an incident side lens 45, an aperture 46 and a condensing lens 47. The laser beam B that has passed through the focusing optical system 44 is focused at a focusing position P. An end face of the optical fiber 60 for introducing the laser beam B into the laser processing device is arranged at the light condensing position P.

In this embodiment, in order to observe the position and the size of the laser converging beam spot incident on the end face of the optical fiber 60, the reflecting mirrors 62 and
A CD camera 61 is provided. The reflecting mirror 62 is provided behind the total reflecting mirror 43, and reflects the weak light leaking from the reflecting mirror 62 toward the CCD camera 61. Therefore,
The CCD camera 61 can observe a laser converging beam spot on the end face of the optical fiber 60 via the converging optical system 44.

On the other hand, the monitor light M extracted in the direction of the optical axis X ′ by the beam splitter 41 is further divided into three measurement lights m by a first semi-transmissive mirror 51 and a second semi-transmissive mirror 52 functioning as light separating means. ₁ , m ₂ and m ₃ . That is, the monitor light M is first transmitted through the first semi-transmissive mirror 51 having a transmittance of about 1/3, whereby the measurement light m ₁ is separated from the monitor light M. Separated measurement beam m ₁ enters the power meter 53, the light intensity is measured. In this embodiment, the power meter 53 functions as a beam intensity fluctuation measuring unit. Since the light intensity of the measurement light m ₁ is proportional to the light intensity of the laser condensed beam at the light condensing position P, the light intensity of the measurement light m ₁ is measured at the light condensing position P It is possible to know the light intensity of the laser focused beam.

Next, the optical axis X ″ is transmitted by the first semi-transmissive mirror 51.
The monitor light M reflected in the direction is further separated by the second semi-transmissive mirror 52 having a transmittance of about 50% into the measurement light m ₂ which is a transmitted light and the measurement light m ₃ which is a reflected light. You. One measurement light m ₂ is condensed by a condensing lens 54 on a condensing point Q on a photodetector 55. In the present embodiment, the condenser lens 54 and the photodetector 55
Condensing position fluctuation detecting means is configured. The photodetector 55 measures the position of the converging point Q of the measurement light m ₂ , and measures the fluctuation of the converging position P based on the fluctuation of the position of the converging point Q.

The other measurement light m ₃ is supplied to the IR sensor 56.
Incident on. The IR sensor 56 has a function of converting infrared light into visible light, and emits visible light from the back surface of the portion irradiated with the infrared light. Therefore, this visible light is
By observing the above, the variation in the size of the incident laser beam B can be measured. In this embodiment, the IR
The sensor 56 and the camera 57 constitute a laser beam size variation measuring unit.

As described above, in this embodiment, the intensity of the laser beam B at the focal position P, the focal position of the laser beam B, and the size of the focused beam spot can be measured. B can be accurately guided to the center of the end face of the optical fiber 60. Further, the CCD camera 61
The end face of the optical fiber 60 can be observed by the laser beam B from the center of the end face of the optical fiber 60.
If the light-condensing position P deviates, this can be easily found.

In this embodiment, the reflectance of the beam splitter 41 is 1%, and the transmittances of the first semi-transmissive mirror 51 and the second semi-transmissive plate 52 are about one third and about 50%, respectively.
Power meter 53, photodetector 55
The reflectance and the transmittance may be set to optimal values according to the sensitivity of the IR sensor 56 and the IR sensor 56.

[0055]

According to the laser condensing position fluctuation measuring device of the present invention, the fluctuation of the condensing position of the laser beam due to drift or the like can be measured using the laser beam. It is possible to adjust the focusing position of the laser beam based on the measured fluctuation while using the laser beam. Therefore, when the laser condensing position fluctuation measuring apparatus of the present invention is used for a nozzle of a laser processing apparatus, processing can be performed with high energy efficiency and high accuracy for a long time. In addition, when a laser beam is introduced into an optical fiber of a laser processing apparatus, the laser beam can be accurately supplied to the center of the end face of the fiber for a long time.

According to the laser beam fluctuation measuring device according to the present invention, it is possible to measure not only the fluctuation of the focusing position of the laser beam but also the light intensity of the laser beam. Moreover, the measurement can be performed while using the laser beam. A laser beam having a constant output can always be supplied to an optical fiber and a processing nozzle of the laser processing apparatus, and the processing accuracy can be improved.

[Brief description of the drawings]

FIG. 1A is a cross-sectional configuration diagram of a laser condensing position fluctuation measuring apparatus according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view showing a state where a fluctuation of a condensing position of a laser beam is detected. Figure,
(C) is a plan view showing the first knife edge reflector, (d)
FIG. 9 is a plan view showing another embodiment of the monitoring means.

FIG. 2A is a cross-sectional configuration diagram of a laser processing nozzle provided with a laser condensing position fluctuation measuring device according to a second embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line AA of FIG. FIG.

FIG. 3 is a schematic configuration diagram of a laser condensing position fluctuation measuring device according to a third embodiment of the present invention.

FIGS. 4A to 4D are plan views showing the beam splitter in FIG.

FIGS. 5A and 5B are plan views showing the beam position detecting device in FIG. 3;

FIG. 6 is a cross-sectional view showing a schematic configuration of a laser condensing position fluctuation measuring device according to a fourth embodiment of the present invention.

FIG. 7 is a plan view showing a configuration of a laser beam fluctuation measuring apparatus according to a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional laser processing nozzle that keeps a laser beam condensing position constant by calculating a distance between a laser beam extraction port and a condenser lens.

FIG. 9 is a configuration diagram of a conventional laser processing nozzle that keeps a laser beam condensing position constant using a power sensor.

FIG. 10 is a configuration diagram of a conventional laser processing nozzle that keeps a laser beam condensing position constant using a distance sensor.

FIG. 11 is a configuration diagram of a conventional laser processing nozzle that measures the thermal deformation of the condenser lens and keeps the focal position of the laser beam constant.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser oscillator 2 ... Telescope 3 ... Bending mirror 4 ... Condensing lens 5a-5d ... 1st knife edge reflector 6a-6d ... 1st optical sensor 7a-7d ... 2nd knife edge reflector 8a-8d ... 2 optical sensors 9a to 9d: knife edge reflectors 10a to 10d: optical sensors 21, 31 ... reflective members 23 ... monitor condenser lenses 24, 34 ... beam position detectors 41 ... beam splitters 43 ... total reflection mirrors 44 ... condensers Optical system 51: First semi-transmissive mirror 52: Second semi-transmissive mirror 53: Power meter 54: Condensing lens 55: Photodetector 56: IR sensor 57: Camera 60: Optical fiber 61: CCD camera 62: Reflecting mirror P: Collection optical position B ... incident laser beam M ... monitor light _{m 1, m 2, m 3} ... measurement light X, X ', X'' ... optical axis

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-281080 (JP, A) JP-A-61-242779 (JP, A) JP-A-3-32482 (JP, A) JP-A-3-28 35891 (JP, A) JP-A-63-194886 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30 102 B23K 26/00-26/18 G02B 7/11

Claims (4)

(57) [Scope of request for utility model registration] 1. A is employed in the optical device used by condensed to a predetermined focusing position of the laser beam emitted from the laser light source device by the condensing optical system having a laser oscillator, the variation of the light converging position A laser condensing position variation measuring device that measures under the use of the laser beam, in the optical path from the laser light source device to the converging position , only when the converging position fluctuates, A laser focusing position fluctuation comprising: monitoring means for extracting a part of the laser beam as monitoring light; and focusing position fluctuation detecting means for detecting fluctuation of the focusing position based on the monitoring light. Measuring device. 2. The monitor means surrounds the laser beam between the focusing optical system and the focusing position.
Provided in Rutotomoni, normal the light converging position is fluctuated
Only a part of the laser beam is reflected when it deviates from the position.
A reflection member disposed at a position where the reflected light can be emitted, wherein the light-condensing position variation detecting means is constituted by a plurality of optical sensors for detecting reflected light from the reflecting member ; 2. The laser condensing position fluctuation measuring device according to claim 1, wherein the fluctuation of the condensing position is measured by the detection. 3. The monitor means is provided between the light-collecting optical system and the light-collecting position, and extracts a part of the laser beam as monitor light to a light-collecting point different from the light-collecting position. A reflection member for condensing light, wherein the light-condensing position fluctuation detecting means is disposed at a light-condensing point of the monitor light, and detects a fluctuation of the light-condensing position of the laser beam by a fluctuation of the light-condensing point of the monitor light. 2. The laser beam condensing position fluctuation measuring device according to claim 1, wherein the beam condensing position detecting device performs the measurement. 4. The monitoring means is a reflection member provided between the laser light source device and the focusing optical system for extracting a part of the laser beam as monitoring light. The monitor includes a monitor condensing optical system that converges monitor light from the reflection member, and a converging position of the laser beam that is disposed at a converging point of the monitor light and that changes the converging point of the monitor light. 2. The laser condensing position fluctuation measuring device according to claim 1, comprising a beam position detecting device for detecting fluctuation.